Siga este enlace para ver otros tipos de publicaciones sobre el tema: Identification of mechanical wood properties.
Tesis sobre el tema "Identification of mechanical wood properties"
Crea una cita precisa en los estilos APA, MLA, Chicago, Harvard y otros
Consulte los 50 mejores tesis para su investigación sobre el tema "Identification of mechanical wood properties".
Junto a cada fuente en la lista de referencias hay un botón "Agregar a la bibliografía". Pulsa este botón, y generaremos automáticamente la referencia bibliográfica para la obra elegida en el estilo de cita que necesites: APA, MLA, Harvard, Vancouver, Chicago, etc.
También puede descargar el texto completo de la publicación académica en formato pdf y leer en línea su resumen siempre que esté disponible en los metadatos.
Explore tesis sobre una amplia variedad de disciplinas y organice su bibliografía correctamente.
1
Šećerović, Amra. "Identification and characterization of molecular players potentially responsible for the mechanical properties of tension wood". Thesis, Orléans, 2016. http://www.theses.fr/2016ORLE2066/document.
Texto completoResumen
Le but de cette thèse était d’identifier les mécanismes moléculaires responsables des propriétés particulières de la couche G et les propriétés mécaniques remarquables du bois de tension (BT). Trois acteurs moléculaires potentiels (des protéines à arabinogalactane avec domaine fasciclin-like (FLA), une protéine chitinase-like (CTL) et une β-galactosidase (BGAL)) ont été choisis et étudiés dans: analyse phylogénétique, analyses d'expression et caractérisation de peupliers transgéniques affectés dans l’expression de chacun de ces acteurs. La caractérisation fine de ce matériel a révélé que CTL2 et les FLA jouent un rôle dans la régulation de la cristallinité de la cellulose dans le BT. CTL2 apparaît également important dans l'organisation de la paroi cellulaire et des propriétés mécaniques des tiges. BGAL a été avant proposé pour une fonction dans modification de pectine RG-I potentiellement important pour des propriétés mécaniques de BT. Le bois de tension exhibe une activité BGAL plus élevée que dans le bois opposé. L’inhibition par RNAi de l’expression de BGAL7, spécifiquement exprimée dans le BT, n’est pas responsable à lui seul de la forte activité BGAL présente dans le BT. En contrepoint à l’étude menée sur le peuplier, nous avons également évalué la présence d’acteurs moléculaires potentiellement responsables des propriétés mécaniques du BT chez le simarouba qui développe dans leur BT des fibres ayant leurs sous-couches de la paroi intermédiaire entre la G et la S2. Des protéines à arabinogalactanes ainsi que des pectines du type RG-I sont présentes dans les fibres de BT de peuplier et de simarouba et pourraient avoir une fonction dans un mécanisme commun de génération des contraintes dans le BT. Finalement, un modèle est proposé sur le rôle présumé des différents acteurs moléculaires étudié dans la régulation des propriétés de la couche G et la génération des fortes contraintes du bois de tensionThe aim of this thesis was to approach the underlying molecular mechanisms responsible for the particular properties of the G-layer and the outstanding mechanical properties of tension wood (TW). Accordingly, three potential molecular players (fasciclin-like arabinogalactan protein (FLA), chitinase-like protein (CTL) and β-galactosidase (BGAL)) were chosen and studied through a phylogenetic analysis, expression analyses and most importantly characterization of RNAi transgenic poplars. This multilevel characterization revealed that CTL2 and FLAs have function in the regulation of cellulose crystallinity in TW. CTL2 was also shown to be important both for the cell wall organization and stem mechanical properties. BGAL was studied in a light of the previously reported modifications of RG-I pectin, potentially important for the mechanical properties of TW. Study of BGAL revealed that the enzyme has higher activity in TW than in opposite wood. BGAL7, whose gene was expressed specifically in TW, does not seem to be responsible for the higher BGAL activity in TW. In comparison to poplar, we analyzed the occurrence of molecular players potentially responsible for TW mechanical properties in simarouba, a tropical species, which develops different TW fiber. Arabinogalactan proteins and RG-I pectin potentially targeted by BGAL were localized in TW fibers both in poplar and simarouba and therefore may be involved in a common mechanism of tensile stress generation in different TW types. A model was finally proposed to elucidate a potential function of the studied molecular players in the regulation of G-layer properties and tensile stress generation
2
Broman, Olof. "Means to measure the aesthetic properties of wood". Doctoral thesis, Luleå tekniska universitet, Träteknologi, 2000. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-16967.
Texto completoResumen
Wood is a biological material with inherent aesthetic properties which can give the final product a competitive advantage over other materials. In this thesis, people’s feelings and preferences for Scots pine (Pinus sylvestris) wood surfaces have been examined. The main objectives of this thesis are to develop methods for measuring people’s preferences toward different looks of wood and to connect the subjective preference data with objective measurements of wood features. It comprises both qualitative and quantitative methods for collecting preference data. Two projection methods, PCA and PLS, were used to analyze the quantitative studies. Interviews made clear that people prefer different blends of wood features. There are two qualitative differences that are of importance for people's impressions and valuations of wood: The overall blend of wood features and divergent features that mismatch in a surface. It was found that divergent features are more important than the overall mixture of features. But if there are no defects that mismatch, the overall mixture will then be the key to a person's appreciation of a wood surface. Wood surfaces should stimulate people's interest and be fresh looking. A clear surface is naturally rather harmonious, elegant and easy to look at. On the other hand, a clear surface should be stimulating to look at, should be exciting and it should not look like an imitation. Knotty surfaces usually are less harmonious. Therefore, questions about harmony, easiness to look at and balance are of importance. Just as for clear surfaces, a knotty surface should also stimulate people's interest, have a fresh look, be exciting and stimulating to look at. The quantitative studies show that it is possible to measure people’s preferences toward wood by a questionnaire technique. The results also show that there are differences in people’s judgments for surfaces with knots and for those without knots. There are stronger connections between questions regarding the overall impression and the final assessment than there are for detailed questions regarding certain wood features. Thirteen questions were pointed out as relevant to use with interviews. Two interview methods were compared. The first method used wood surfaces and the second used computer images with the same wood surfaces applied to an example product, a kitchen cabinet. The results show that the two methods are comparable and useful. It was shown that it is possible to some extent to connect subjective preference data with objective wood feature measurements. Results show that a lot of wood feature measurements are needed and that it is a multivariate problem. Concerning the measurements, it seems easier to find features that negatively affect people’s liking than to find the opposite. Among the most important variables were those that detect different kinds of feature distribution over a wood surface, and especially those variables that detect a deviation in center of gravity. Increased knowledge about people’s preferences for the aesthetic properties of wood will lead to a better understanding of which wood features should be measured and controlled in the future.Godkänd; 2000; 20061116 (haneit)
3
Oksman, Kristiina. "Improved properties of thermoplastic wood flour composites". Doctoral thesis, Luleå tekniska universitet, Materialvetenskap, 1997. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-26513.
Texto completoResumen
In this study the properties of composites made of wood flour and thermoplastics have been investigated. In order to improve the interfacial adhesion between hydrophobic and nonpolar thermoplastics and hydrophilic and polar wood flour different additives have been used as compatibilizers in composites systems. The interaction between a wood filler and thermoplastic matrix, with and without compatibilizers, has been studied using conventional mechanical testing, impact testing, dynamic mechanical thermal analysis (DMTA), electron microscopes and infrared spectroscopy. Tests of mechanical properties, such as maximum tensile strength, tensile modulus and impact strength have shown that maleic anhydride grafted styrene-ethylene/butylene-styrene triblock copolymer (SEBS-MA) acts as a compatibilizer in the composite system. The SEBS-MA improves the stress transfer from the matrix to the wood particles and forming an flexible interphase around the wood particle and therefore improves the impact properties. The DMTA measurements indicated that there is an interaction between the wood surfaces and the maleic anhydride part of the SEBS-MA copolymer, and also between PS and wood. Morphological studies with SEM and TEM showed that the addition of SEBS-MA improved the adhesion between the wood particles and polymer matrix and that the compatibilizer is located at the interphase region between them. An infrared spectroscopy study indicated that the MA in the SEBS may react with the wood by forming hydrogen- and esterbonds and also possibly interaction between PS and wood.Godkänd; 1997; 20061128 (haneit)
4
Kirkpatrick, John Warren. "Mechanical and physical properties of preservative-treated strandboard". Master's thesis, Mississippi State : Mississippi State University, 2005. http://sun.library.msstate.edu/ETD-db/ETD-browse/browse.
Texto completo
5
Noel, Matthieu. "Modélisation déterministe et probabiliste de la rupture par champ de phase et identification expérimentale pour la fissuration des structures en bois dans l’ameublement". Electronic Thesis or Diss., Université Gustave Eiffel, 2024. http://www.theses.fr/2024UEFL2061.
Texto completoResumen
Dans le domaine de l'ameublement, garantir la sécurité des structures conformément aux normes européennes représente un enjeu important pour les fabricants de meubles. Avant leur commercialisation, les meubles sont soumis à des tests de validation normalisés, qui ne permettent de connaître leur comportement mécanique qu'a posteriori. Cette thèse vise à développer des outils de modélisation et de simulation numérique pour prédire la rupture par fissuration au niveau des connexions entre les éléments de meuble. Pour atteindre cet objectif, l'approche méthodologique combine la modélisation et la simulation numérique avec des essais expérimentaux. Elle utilise la méthode des éléments finis couplée à des modèles de rupture/endommagement par champ de phase pour simuler la fissuration dans des matériaux élastiques linéaires isotropes et anisotropes, dans un cadre déterministe et probabiliste. Une campagne d'essais expérimentaux est menée sur des échantillons d'épicéa troués soumis en compression uniaxiale, afin de reproduire les mécanismes de fissuration observés dans des structures réelles, notamment dans les connexions de lits en hauteur. Une procédure d'identification est développée et mise en place pour caractériser les propriétés élastiques et d'endommagement de l'épicéa, en exploitant notamment des mesures expérimentales de champs de déplacement obtenues par corrélation d'images numériques. Une méthode d'accélération des simulations d'endommagement par champ de phase est proposée pour réduire leur coût élevé en temps de calcul. Cette approche permet de prédire, indépendamment du type de connexions, le déplacement ou la force critique précédant l'amorçage de la fissuration. Les résultats numériques indiquent que, sous réserve d'appliquer des conditions aux limites réalistes et d'avoir correctement identifié les propriétés du matériau, le critère d'amorçage de fissure s'avère utile pour prédire l'emplacement des zones potentiellement endommagées/fissurées et fournir un ordre de grandeur cohérent pour l'effort ou le déplacement nécessaire à l'initiation de la fissuration. Ce critère requiert seulement une unique simulation dans le domaine élastique linéaire, suivi d'un post-traitement avec un modèle d'endommagement par champ de phase, afin de faciliter son utilisation dans un contexte industriel, en particulier le secteur de l'ameublement. Les outils numériques développés, accessibles en open source, pourraient aider les industriels de l'ameublement à prédire la rupture fragile dans le bois et à optimiser la conception des meubles, tout en garantissant la conformité aux normes de sécuritéIn the furniture industry, ensuring the safety of structures in accordance with European standards presents a significant challenge for furniture manufacturers. Before commercialization, furniture are subjected to standardized validation tests, which only allow for a retrospective understanding of its mechanical behavior. This thesis aims to develop modeling and numerical simulation tools to predict the cracking failure mechanism at the connections between furniture elements. To achieve this objective, the methodological approach combines modeling and numerical simulation with experimental testing. It employs the finite element method coupled with phase-field fracture/damage models to simulate cracking in linear elastic isotropic and anisotropic materials within a deterministic and probabilistic framework. An experimental testing campaign is conducted on perforated spruce wood samples subjected to uniaxial compression to reproduce the cracking mechanisms observed in real structures, particularly in the connections of high loft beds. An identification procedure is developed and implemented to characterize the elastic and damage properties of spruce wood, in particular by exploiting experimental displacement field measurements obtained through digital image correlation. A method for accelerating phase-field damage simulations is proposed to reduce their high computational cost. This approach allows for the prediction, independently of the type of connections, of the displacement or critical force preceding crack initiation. The numerical results indicate that, provided realistic boundary conditions are applied and the material properties are correctly identified, the crack initiation criterion is useful for predicting the location of potentially damaged/cracked areas and providing a consistent order of magnitude of the force or displacement required to initiate cracking. This criterion only requires a single linear elastic simulation, followed by a post-processing with a phase-field damage model, to facilitate its use in an industrial context, in particular the furniture sector. The numerical tools developed, available in open source, could help furniture manufacturers to predict brittle fracture in wood and optimize furniture design, while guaranteeing compliance with safety standards
6
Gade, Jan-Lucas. "Mechanical Properties of Arteries : Identification and Application". Licentiate thesis, Linköpings universitet, Mekanik och hållfasthetslära, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-159942.
Texto completoResumen
In this Licentiate of Engineering thesis, a method is proposed that identifies the mechanical properties of arteries in vivo. The mechanical properties of an artery are linked to the development of cardiovascular diseases. The possibility to identify the mechanical properties of an artery inside the human body could, thus, facilitate disease diagnostization, treatment and monitoring. Supplied with information obtainable in the clinic, typically limited to time- resolved pressure-radius measurement pairs, the proposed in vivo parameter identi- fication method calculates six representative parameters by solving a minimization problem. The artery is treated as a homogeneous, incompressible, residual stress- free, thin-walled tube consisting of an elastin dominated matrix with embedded collagen fibers referred to as the constitutive membrane model. To validate the in vivo parameter identification method, in silico arteries in the form of finite element models are created using published data for the human abdominal aorta. With these in silico arteries which serve as mock experiments with pre-defined material parameters and boundary conditions, in vivo-like pressure-radius data sets are generated. The mechanical properties of the in silico arteries are then determined using the proposed parameter identification method. By comparing the identified and the pre-defined parameters, the identification method is quantitatively validated. The parameters for the radius of the stress-free state and the material constant associated with elastin show high agreement in case of healthy arteries. Larger differences are obtained for the material constants associated with collagen, and the largest discrepancy occurs for the in situ axial prestretch. For arteries with a pathologically small elastin content, incorrect parameters are identified but the presence of a diseased artery is revealed by the parameter identification method. Furthermore, the identified parameters are used in the constitutive membrane model to predict the stress state of the artery in question. The stress state is thereby decomposed into an isotropic and an anisotropic component which are primarily associated with the elastin dominated matrix and the collagen fibers, respectively. In order to assess the accuracy of the predicted stress, it is compared to the known stress state of the in silico arteries. The comparison of the predicted and the in silico decomposed stress states show a close agreement for arteries exhibiting a low transmural stress gradient. With increasing transmural stress gradient the agreement deteriorates. The proposed in vivo parameter identification method is capable of identifying adequate parameters and predicting the decomposed stress state reasonably well for healthy human abdominal aortas from in vivo-like data.In diesem Lizentiat der Ingenieurwissenschaften wird eine Methode zur Identifikation der mechanischen Eigenschaften von Arterien in vivo vorgestellt. Die mechanischen Eigenschaften einer Arterie sind mit der Ausbildung kardiovaskulärer Krankheiten verknüpft und deren Identifikation hat daher das Potenzial die Diagnose, die Behandlung und die Überwachung dieser Krankheiten zu verbessern. Basierend auf klinisch möglichen Messungen, die üblicherweise auf ein zeitaufgelöstes Druck-Radiussignal limitiert sind, werden sechs repräsentative Parameter durch Lösen eines Minimierungsproblems berechnet. Die sechs Parameter sind dabei die Eingangsparameter des zur Hilfe gezogenen konstitutiven Schalenmodells welches eine Arterie als eine homogene, inkompressible, restspannungsfreie und dünnwandige Röhre beschreibt. Weiterhin wird angenommen, dass die Arterienwand aus einer elastindominierten Matrix mit eingebetteten Kollagenfasern besteht. Um die in vivo Parameteridentifikationsmethode zu validieren, werden in silico Arterien in Form von Finite Elemente Modellen erstellt. Diese in silico Arterien beruhen auf publizierten Materialparametern der menschlichen Abdominalaorta und dienen als Pseudoexperimente mit vordefinierten mechanischen Eigenschaften und Randbedingungen. Mit diesen Arterien werden in vivo-ähnliche Druck-Radiussignale erstellt und anschliesend werden ihre mechanischen Eigenschaften mit Hilfe der Parameteridentifikationsmethode bestimmt. Der Vergleich der identifizierten und der vordefinierten Parameter ermöglicht die quantitative Validierung der Methode. Die Parameter des spannungsfreien Radius und der Materialkonstanten für Elastin weisen hohe Übereinstummung im Falle gesunder Arterien auf. Die Abweichung der Materialkonstanten für Kollagen sind etwas gröser und der gröste Unterschied tritt beim axialen in situ Stretch auf. Für Arterien mit einem pathologisch geringen Elastinbestandteil werden falsche Parameter identifiziert, wobei die Parameteridentifikationsmethode eine krankhafte Arterie offenlegt. Weiterhin werden mit Hilfe der identifizierten Parameter und des konstitutiven Schalenmodells der Spannungszustand in der Arterienwand berechnet. Dieser ist dabei aufgeteilt in einen isotropen und einen anisotropen Anteil. Der isotrope Anteil wird mit der elastindomierten Matrix und der anisotrope Anteil mit den Kollagenfasern verknüpft. Um die Genauigkeit des berechneten Spannungszustandes beurteilen zu können, wird dieser mit dem Zustand in den in silico Arterien verglichen. Im Fall von Arterien, die einen geringen transmuralen Spannungsgradienten aufweisen, entspricht der berechnete Spannungszustand dem in silico Zustand. Mit zunehmendem transmuralen Spannungsgradienten lässt die Übereinstimmung nach. Für die gesunde menschliche Abdominalaorta ist die entwickelte in vivo Parameteridentifikationsmethode in der Lage, basierend auf in vivo-ähnlichen Messsignalen, adäquate Parameter zu identifizieren und einen zufriedenstellenden Spannungszustand zu berechnen.
I denna licentiatavhandling föreslås en metod för att identifiera mekaniska egenskaper hos artärer in vivo. De mekaniska egenskaperna är kopplade till utvecklingen av hjärt-kärlsjukdomar, och möjligheten att identifiera dessa egenskaper skulle således kunna underlätta diagnostisering, behandling och uppföljning av dessa sjukdomar. Den förslagna metoden använder kliniskt mätbara tryck-radie-signaler och löser ett minimeringsproblem för att bestämma sex parametrar som beskriver kärlets mekaniska egenskaper. Artären modelleras som ett homogent, inkompressibelt och spänningsfritt tunnväggigt rör där kärlväggen utgörs av en elastindominerad matris armerad med inbäddade kollagenfibrer. För att validera parameteridentifieringen skapas en uppsättning representativa, virtuella artärer med hjälp av finita element. Dessa in silico-artärer baseras på publicerade data för mänsklig bukaorta och används för att generera fiktiva tryckradie-signaler vilka sedan matas in i den förslagna modellen. Genom att parametrar och randvillkor för in silico-artärerna är kända fungerar dessa som en kontroll mot vilka resultatet från parameteridentifieringen kan jämföras. Parametrarna som beskriver den icke trycksatta radien och den elastindominerade matrisen visar god överensstämmelse med de in silico-artärerna för friska kärl. Större diskrepans erhålls för de parametrar som associeras med kollagenet, och den största avvikelsen erhålls för den parameter som beskriver den axiella försträckningen. För artärer med patologiskt lågt elastininnehåll identifieras felaktiga parametrar, men resultatet avslöjar ändå tydligt en sjuk artär. De identifierade parametrarna har också använts för att jämföra spänningstillst åndet i membranmodellen och in silico-artäreren. Spänningstillståndet har delats upp i en isotrop och en anisotrop komponent svarande mot, i huvudsak, den elastindominerade matrisen samt kollagenfibrerna. Resultatet visar en mycket god överensstämmelse för bägge komponenterna hos in silico-artärer med låg spänningsgradient genom väggen. Med ökande spänningsgradient försämras dock överensstämmelsen. Resultatet visar att den förslagna metoden är kapabel att identifiera adekvata parametrar och att förutsäga spänningskomponenterna i en frisk aorta.
7
Ashaduzzaman, Md. "Physico-mechanical and decay resistance properties of bio-resin modified wood". Thesis, Bangor University, 2014. https://research.bangor.ac.uk/portal/en/theses/physicomechanical-and-decay-resistance-properties-of-bioresin-modified-wood(f4588ffc-250d-4f89-95f5-8f9ea381dba7).html.
Texto completo
8
Huang, Sheng. "Experiment study of the mechanical properties of timber materials under various humidity condition". Thesis, University of Macau, 2018. http://umaclib3.umac.mo/record=b3950672.
Texto completo
9
Ozden, Seray. "The relationship between the anatomy and mechanical properties of different green wood species". Thesis, University of Manchester, 2016. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.684776.
Texto completoResumen
Trees are exposed to many stresses over their lifetime and withstand them due to their woody skeleton which provides excellent mechanical support. Wood has therefore been one of the most used materials throughout the history of humanity. However, the mechanical properties of wood vary considerably depending on wood anatomy and also show significant differences between and within trees. Wood is a cellular solid, characterised by a high degree of anisotropy at all levels of organisation and is formed by cells which are oriented largely in the longitudinal and radial directions, making wood mechanics rather complicated. Therefore, there is a need for an understanding of the mechanical properties of wood in different species and in different parts of the tree and its relationship to wood anatomy. This study began with two investigations into the transverse toughness of green trunk wood in different tree species including both hardwood and conifers. Double-edge notched tensile tests were conducted on the specimens to quantify their specific fracture energies and evaluate their failure fashions. The influence of wood anatomy on the toughening mechanism of wood was observed using both electron microscopy and light microscopy. It was found that the fracture properties of woods were mainly affected by the wood density and anatomy. Hardwoods were found to have higher fracture energies than conifers due to their denser woods and higher volume fraction of rays. The results also found that the specific fracture energies of RL and RT systems were around 1.5-2 times greater than TL and TR systems. This difference was mainly explained by the presence of rays which provided toughness in the radial direction, at least in hardwoods, as breaking across rays resulted in spiral fractures of the cell walls. The mechanical properties of green branches and coppice shoots of three temperate tree species (chestnut, sycamore and ash), were then investigated at three distances from the tip. The study also investigated how bending failure was influenced by the morphology and anatomy of branches and coppice shoots. Coppice shoots were shown to be more likely to buckle in bending, whereas branches failed with a clean fracture. It was shown that ash and sycamore had greater properties in their coppice shoots than their branches, while chestnut showed better properties in their branches. It was suggested that this occurred because increasing the leaf node frequency resulted in a decrease in mechanical properties; ash and sycamore had more leaf nodes in their branches, thus lower properties in their branches, while chestnut had more leaf nodes in its coppices. The mechanical properties also decreased from base to tips of branches and coppice shoots because of falls in diameter of shoots and wood density. The results also suggested why coppice shoots can act as a useful structural material. Finally, this thesis investigated how and why the fracture properties vary around the structure of tree forks. The fracture properties of green hazel forks were examined using double-edge notched tensile tests in the RT and TR directions. The fracture surfaces were also observed using scanning electron microscopy in both fracture systems. The results showed that the central apex of forks were considerably tougher than other locations, suggesting they provide the load-bearing capacity of tree forks. It was shown that the increased toughness was related to both higher wood density and an interlocking wood grain pattern. Interestingly, the TR fracture system was found to be tougher than the RT fracture system at the central apex of forks, probably related to the orientation of the fibres. These results provide insight into the relationship between wood mechanics and anatomy, particularly showing the importance of rays. They can also help us understand how our ancestors shaped wood and designed tools and how we could design better structures.
10
Anderson, Scott Powell. "Wood fiber reinforced bacterial biocomposites effects of interfacial modifers and processing on mechanical and physical properties /". Online access for everyone, 2007. http://www.dissertations.wsu.edu/Thesis/Fall2007/S_Anderson_100507.pdf.
Texto completo
11
Smulski, Stephen John. "Flexural behavior of a glass fiber reinforced wood fiber composite". Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/53596.
Texto completoResumen
The static and dynamic flexural properties of a wood fiber matrix internally reinforced with continuous glass fibers were investigated. When modelled as a sandwich composite, the static flexural modulus of elasticity (MOE) of glass fiber reinforced hardboard could be successfully predicted from the static flexural MOE of the wood fiber matrix, and the tensile MOE and effective volume fraction of the glass fiber reinforcement. Under the same assumption, the composite modulus of rupture (MOR) is a function of the reinforcement tensile MOE and effective volume fraction, and the matrix stress at failure. The composite MOR was predicted on this basis with limited success.
The static flexural modulus of elasticity, dynamic modulus of elasticity, and modulus of rupture of glass fiber reinforced hardboard increased with increasing effective reinforcement volume fraction. The logarithmic decrement of the composite decreased with increasing effective reinforcement volume fraction. Excellent linear correlation found among flexural properties determined in destructive static tests and nondestructive dynamic tests demonstrated the usefulness of dynamic test methods for flexural property evaluation.
The short-term flexural creep behavior of glass fiber reinforced hardboard was accurately described by a 4-element linear viscoelastic model. Excellent agreement existed between predicted and observed creep deflections based on nonlinear regression estimates of model parameters.Ph. D.
12
Bhattacharjee, Sujal. "Impact of Recycling on the Mechanical and Thermo-Mechanical Properties of Wood Flour/High Density Polyethylene and Wood Flour/Poly Lactic Acid Composites". Thesis, North Dakota State University, 2016. https://hdl.handle.net/10365/28285.
Texto completoResumen
This research concentrates on the recyclability of two wood plastic composites (WPCs) - wood flour/HDPE and wood flour/PLA composites. Two different filler loadings (30 and 50 wt%) were considered for each polymer composite. Each composite formulation contained 3 wt% of a coupling agent, and was individually recycled up to six times by extrusion process. Samples for mechanical and thermo-mechanical tests were prepared by injection molding. All test results were statistically analyzed with a confidence level of 95%. Additional tests such as fiber length measurement, GPC, DSC, TGA, FTIR, and SEM were also performed at specific reprocessing cycles. After reprocessing six times, all formulations showed lower relative decrease in most stiffness properties but higher relative increase in most strain properties. In strength properties, both HDPE composites showed lower relative decrease after reprocessed six times; however, higher and lower filler PLA composites showed sharp decrease reprocessed at second and six times respectively.
13
Paredes, Heller Juan Jacobo. "The Influence of Hot Water Extraction on Physical and Mechanical Properties of OSB". Fogler Library, University of Maine, 2009. http://www.library.umaine.edu/theses/pdf/ParedesJJ2009.pdf.
Texto completo
14
Eskandari, Hani. "On the identification of mechanical properties of viscoelastic materials". Thesis, University of British Columbia, 2009. http://hdl.handle.net/2429/6051.
Texto completoResumen
Commonly used medical imaging techniques can render many properties of the anatomy or function, but are still limited in their ability to remotely measure tissue mechanical properties such as elasticity and viscosity. A remote and objective palpation function would help physicians in locating possible tumors or malignancies. The branch of medical imaging that characterizes tissues mechanical properties in a non-invasive manner has enjoyed increasing interest in the past two decades. The basic principle is to apply an excitation, such as tissue compression, to a region of interest and measure the resulting tissue deformation. Tissue mechanical properties can then be inferred from the observed deformation at multiple locations in the region, and the properties can be displayed as an image. If the excitation is dynamic, the deformation is considered as a motion field that varies in time and location over the region of interest. Ultrasound is particularly well suited for measuring motion fields due to its ability to image in real-time, low cost, low risk and ease-of-accessibility. The focus of this thesis is the estimation of the viscoelastic parameters such as Young's modulus, viscosity and relaxation-time. For this purpose, a motion estimation method is proposed to measure axial tissue displacements from the peak of the ultrasound radio frequency signals. The displacements can be further processed to identify the mechanical properties. Two methods were developed: the first one is based on a one dimensional Voigt's model of soft tissue and the second one is based on a finite element model. In the first method, a single frequency or wide-band excitation is applied to the tissue and the local relaxation-time is recovered from the phase difference between the strains or displacements. In this method, the elasticity can also be reconstructed from the magnitudes of the spectra. In the second approach, a novel dynamic finite element model is proposed for the incompressible soft materials. An inverse problem of viscoelasticity is solved iteratively to reconstruct the viscosity and elasticity based on a two or three dimensional model. The theoretical aspect of compressional elastography and longitudinal wave propagation is investigated. It is shown to be feasible to apply dynamic or transient compressional excitation to recover the dynamic properties of soft tissue.
15
Erwinsyah, Erwinsyah. "Improvement of Oil Palm Wood Properties Using Bioresin". Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2008. http://nbn-resolving.de/urn:nbn:de:bsz:14-ds-1211880694953-36973.
Texto completoResumen
Die ausWestafrika stammende Ölpalme (Elaeis guineensis Jacq) ist zur populärsten Kulturpflanze in Südostasien geworden. Als Haupterzeugnisse dieser Pflanze gelten die Öle der Früchte und der Fruchtkerne. Die weltweite Nachfrage nach diesen beiden Haupterzeugnissen nimmt sehr rasch zu. Ursache hierfür ist die breite Anwendungspalette dieser Pflanzenöle, wie z.B. Bratöl, ölbasierte Chemikalien und ölbasierte Nahrungsmittel, Kosmetika, Waschmittel, Biobrennstoff usw. Indonesien und Malaysia sind die Hauptproduzenten und Hauptlieferanten solcher Produkte und decken über 85% des weltweiten Bedarfs. Mit Extensivierung der Ölpalmplantagen sehen sich die Erzeugerländer zunehmend mit ernstzunehmenden Umweltprobleme konfrontiert, da nach Erreichen der wirtschaftlichen Lebenspanne (Umtriebszeit) von 25 Jahren große Mengen an festen, biologischen Abfallstoffe bei der Neubegründung der Bestände anfallen. So sollen z.B. im Jahre 2010 laut Vorhersagen mehr als 20 Mill. Kubikmeter Ölpalmen- Holz jährlich anfallenOil palm (Elaeis guineensis Jacq) becomes the most popular crop, especially in Southeast Asia, than its origin,West Africa. World demand of two main products from this crop (e.g. crude palm oil and palm kernel oil) increases very rapidly, due to very wide ranges use of these vegetable oils for industrial purposes, such as fried oil, oleo-chemical and -food, cosmetics, detergent, biofuel and etc. Indonesia and Malaysia are the main producers and supplying more than 85% of world consumption. On the other hand, due to the economic life span of this popular crop (25 years), the producer countries have been facing a serious environmental problems concerning to the solid biowaste handling of oil palm industry, particularly the oil palm trunk after replanting activity. Starting 2010, it is predicted that more than 20 millions cubic meter biomass from oil palm trunk available annually
16
Eriksson, Daniel. "Wood - an anatomical structure in the tree and an engineering material in industry : prediction of material properties in managed Scots pine stands in the forest /". Umeå : Dept. of Forest Ecology and Management, Swedish University of Agricultural Sciences, 2008. http://epsilon.slu.se/200873.pdf.
Texto completo
17
Naderi, Nader. "Influence of the planing on the physical, mechanical and gluing properties of wood". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ39378.pdf.
Texto completo
18
Li, Junqiu. "Physical and Mechanical Properties of Medite® MDF Exterior from Acetylated Wood Fibers". Thesis, Linnéuniversitetet, Institutionen för maskinteknik (MT), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-76444.
Texto completoResumen
Currently, the demand for wood-based panels has been growing solidly in European countries. Medium density fibreboard (MDF) manifests the potentialities for outstanding physical and mechanical properties. However, MDF from different fiber sources is normally designed for internal applications due to the poor moisture resistant capability. This study was conducted on acetylated MDF (Medite® MDF Exterior) to evaluate how physical (i.e. density, moisture content, dimensional stability, thickness swelling) and mechanical (i.e. modulus of elasticity, internal bonding strength before and after accelerated aging, bending stiffness and bending strength) properties behave at different relative humidity (i.e. 35 %, 65 % and 85 % RH at constant temperature of 20 ℃) levels. Bending stiffness was measured non-destructively by means of resonance method. The material used for control samples was commercial MDF. The size, quantity, conditioning and test method were followed in accordance with respective standards. The results showed that physical and mechanical properties were less influenced by Medite® MDF Exterior compared to commercial MDF. Medite® MDF Exterior were superior to commercial MDF in moisture resistance. Medite® MDF Exterior had more stable mechanical properties than commercial MDF with the changes of relative humidity.
19
Saleh, Salimeh [Verfasser]. "Hierarchical Mechanical Properties of Wood Cell Wall in Microscale and Nanoscale / Salimeh Saleh". Göttingen : Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2021. http://nbn-resolving.de/urn:nbn:de:gbv:7-21.11130/00-1735-0000-0008-5911-1-2.
Texto completo
20
Solem, Benjamin, Ante Vallien y Philip Wernstedt. "Applying Thermal Diffusion Galvanization on Wood Screws : Effects on Corrosion Resistance and Mechanical Properties". Thesis, KTH, Materialvetenskap, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-205234.
Texto completoResumen
Today, fastening articles such as screws and nails are treated with different surface coatings to withstand corrosion. The Swedish distributor ESSVE® Produkter AB uses a nano coating called CorrSeal™ for high corrosion protection of their screws. Thermal diffusion galvanization (TDG) is a more environmentally friendly method that the company seeks to use as replacement for the current treatment. This process of zinc diffusion is carried out at around 400 °C for several hours. The aim of the project is to investigate the possibility to surface treat a wood screw using TDG. The elevated temperature is suspected to decrease the hardness of the hardened screw. Therefore, a hardened and tempered screw without surface treatment is sent to a TDG facility. Industrial furnaces are used for similar heat treatments of screws with different hardenings. Both processes are analyzed by evaluating the results of hardness, bending, and microscopy. No immediate correlation between the TDG process and heat treatment in the industrial furnaces is found. Results show that the tested screws softened to a higher degree in the TDG process compared to treatment in the industrial furnaces. The mechanical properties of the tested screws, after the TDG process, are not acceptable. The zinc layer thickness on the screws is uneven yet believed to meet the required demands on corrosion resistance. Results also show that incorporating the TDG process in the tempering step is essential to meet the demands on hardness. Additionally, changing the composition of the material can lead to higher resistance against softening at the elevated temperatures. Further research is however needed to present a screw with sufficient corrosion resistance from the TDG process that will meet the demandson hardness and bending.
21
Tidball, Mackenzie E. "Identification of Nonlinear Constitutive Properties of Damping Coatings". Wright State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=wright1544891984582991.
Texto completo
22
Forde, Kohler Lois J. "The effects of ophiostoma piliferm on wood pulp : investigation". Thesis, Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/5982.
Texto completo
23
Tabakci, Alican. "Mechanical Properties Identification Of Viscoelastic / Hyperelastic Materials Based On Experimental Data". Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612634/index.pdf.
Texto completoResumen
Mechanical simulation of viscoelastic materials and assigning a viscoelastic
material to the modeled parts in the simulations are difficult task. For the
simulations, material model should be well chosen and material coefficients of the
chosen models should be known.
In order to obtain accurate simulations, hyperelastic characteristics of the
viscoelastic materials should be investigated and hyperelastic model should be
incorporated in the solutions. Material models and material model&rsquos coefficients are chosen with the help of mechanical tests/experiments for these situations. The main goal of this thesis is to optimize material model&rsquo
s coefficients by using an indenter test setup results and inverse finite element modeling. To achieve this, firstly by using a haptic device and other required equipments an indenter setup was prepared to test the materials mechanically. Inverse finite element modeling method is used in order to model the materials according to their viscoelastic and hyperelastic characteristics. The model obtained from analysis was optimized by using the results obtained from indenter setup according to experimental test data. By doing this, the correctness of the model chosen by inverse finite element modeling was proved for the tested material and material model coefficients were calculated correctly.
24
Johns, Brian Douglas. "Experimental verification of pointwise identification method for capturing heterogeneous properties in membranes". Thesis, University of Iowa, 2010. https://ir.uiowa.edu/etd/824.
Texto completo
25
How, Seok Sean. "Experimental Investigation and Mathematical Modelling Of Mechanical Properties Of Shooks And Finger Jointed Timber". Thesis, University of Canterbury. Department of Chemical and Process Engineering, 2015. http://hdl.handle.net/10092/10127.
Texto completoResumen
The issue on variability of mechanical properties within wood has found to be increasingly prominent in recent years. On the other hand, it is known that uniformity of wood properties is essential in quality control in the timber manufacturing such as manufacturing of Glued Laminated (Glulam) timber. The AS/NZS 1328 P2 specified that the overall mechanical properties of Glulam timber can be estimated based on the MOE of the finger jointed laminates and the arrangement of the corresponding laminates. In relating to the above standard, optimisation in the arrangement of shooks’ location along the finger jointed laminate will enable determination of the overall MOE of laminates, as well as optimise the utilisation of feedstocks. In this study, a deterministic model was developed in relating the local shook’s modulus of elasticity (MOE) with the overall MOE of the corresponding finger jointed timber based on the principle of the Moment of Curvature. The projected overall MOE is calculated as a function of lengths and MOEs of individual shooks in the finger joint timber. The effect of shooks’ location can also be determined from the model. Numerical derivation of the model was addressed and the analyses of the relationships between the local shook MOEs, the overall MOE, and bending strength (MOR) were assessed. Experimental results showed that the model can effectively predicts the overall MOE, particularly on shook combinations with random and large standard deviations in shook MOEs. The errors of the predictive model were ranged from -8.17% to +0.81%. Results from the assessment on the relationships between the overall MOE and bending MOR indicated that wood failure in the combinations of small standard deviations shook MOEs was most likely to occur at the weakest point, however, wood failures may not necessarily occur in the shook with the lowest MOE in the asymmetrical MOE arrangements. This also applies to the finger jointed timber with combinations of shooks with large standard deviations for local MOEs.
In addition, the relationship between dynamic MOE of shooks and the static bending overall MOE were assessed. A linear regression has been suggested for the adjusted shooks dynamic MOE at 36 mm thickness. The predictability of the model could further improve when the shook MOEs were sorted according to sawing pattern and the proposed model for quarter sawn is suggested.
Lastly, economic analysis was performed based on the models available in literature and the developed model in this study. Models reported in the literature including the arithmetic mean model and model based on the shook’s minimum MOE. The results from economic analysis showed that the study’s model was most cost effective in predicting the cost of shooks based on the predicted overall finger jointed MOE using the model as compare to the arithmetic mean and the minimum shook MOE method. In conclusion, the proposed model has demonstrated to be unique, simple, effective and robust in predictive applications.
26
Wilson, David Edward. "Structural Properties of ICLT Wall Panels Composed of Beetle Killed Wood". BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/3230.
Texto completoResumen
Interlocking Cross Laminated Timber (ICLT) wall panels are a new wood construction product similar to Cross Laminated Timber panels. Besides being an innovative structural system, they also utilize beetle killed timber from many of the forests that have been devastated by the Mountain Pine Beetle. Three tests were performed on three ply ICLT panels measuring 8 feet (2.44m) wide, 8 feet (2.44m) tall and 8.5 inches (21.6cm) thick to determine the racking, flexural and axial strengths of the wall panels. After each test was performed the walls were disassembled and investigated for cause of failure. Using the data from the tests as a benchmark, simple analytical models to predict the design capacities of the walls for racking, flexural, and axial strengths were established. The analytical models for racking strength, flexural strength and axial strength predicted reasonably well the measured strength values. Additional testing is necessary to increase the available database, further validate the analytical models developed, better understand the structural performance of ICLT panels, and establish acceptable design methodology for ICLT wall panels.
27
Dowse, George Patrick. "Selected mechanical properties and the structural grading of young Pinus patula sawn timber". Thesis, Stellenbosch : University of Stellenbosch, 2010. http://hdl.handle.net/10019.1/5341.
Texto completoResumen
Thesis (MScFor (Dept. of Forest and Wood Science)--University of Stellenbosch, 2010.ENGLISH ABSTRACT: In this study 1345 pieces of 38x114 mm timber sawn from 16-20 year-old Pinus patula trees were obtained from a wide variety of sites along the Mpumalanga escarpment in South Africa. The samples were tested for various mechanical and physical properties. The objectives of this study were (1) to determine the variation in the bending strength, tension strength, and stiffness of the sawn timber, (2) to assess the efficiency of the current visual and mechanical grading rules on this sample, and (3) to evaluate the potential of some indicator properties to be used as structural grading parameters on this resource. A large number of non-destructive measurements were performed on all the samples, including scanning of the boards with a commercial X-ray density scanner, moisture content measurement, growth ring measurements, warp measurement, acoustic frequency measurement and measurement of the stiffness using a mechanical grader. The data from the X-ray density scanner was used to calculate a number of knot-related variables for each board. Visual grading according to the SANS 1783-2 (2005) specifications for structural timber was performed by a certified grader on all the boards. The timber was divided into two groups for destructive testing, one group each for bending and tension tests. Tests were conducted according to the SANS 6122 (1994) method for in-grade testing. Due to the sampling method followed, the destructive tests effectively used a random placement of defects with regard to the load application position. From the destructive tests the modulus of elasticity (MOEedge), bending strength (MOR) and tensile strength were determined. The study showed that the MOEedge of the sawn timber was far below the requirements of the current national standard (SANS 10163-1) for all of the visual and mechanical grades. The mean MOEedge of the visually graded S5 timber was about 30% lower than required. The 5th percentile values for bending strength of all the visual and mechanical grades were above the required values of SANS 10163-1. The 5th percentile values for tensile strength of all the visual and mechanical grades were similar to that required by the SANS 10163-1 standard. Correlations between flatwise measured MOE (MOEflat) and edgewise measured MOE (MOEedge) were smaller than expected, as well as the correlations between both MOEedge and MOEflat with MOR. Dynamic MOE (MOEdyn), calculated from acoustic frequency tests on the timber, was found to be the best single predictor of MOEedge, MOR and tension strength. Multiple regression analysis showed that a combination of MOEdyn, density and knot parameters can be used to improve the predictability of some of the strength and stiffness characteristics of the timber. It is recommended that a comprehensive study on the structural grading of SA Pine be performed which includes (1) an analysis of market requirements in terms of strength and stiffness properties of timber, (2) in-grade testing of a representative sample of structural timber in South Africa, and (3) a review of the standards used in South Africa to regulate the structural grading of timber.
AFRIKAANSE OPSOMMING: In hierdie studie is 1345 stukke 38x114 mm 16-20 jaar-oue Pinus patula planke, afkomstig van ‘n wye verskydenheid groeiplekke teen die Mpumalanga platorand in Suid Afrika, gebruik. Die planke is getoets vir verskeie meganiese sowel as fisiese eienskappe. Die doelwitte van hierdie studie was om (1) die variasie in buigsterkte, treksterkte en styfheid van die gesaagde planke te bepaal, (2) die effektiwiteit van die huidige visuele -en meganiese graderingsreëls op hierdie monster planke vas te stel, en (3) die potensiaal te evalueer van sommige eienskappe wat gebruik kan word as strukturele graderingsparameters. ‘n Groot hoeveelheid nie-destruktiewe toetse is op alle planke uitgevoer, wat ingesluit het skandering van planke met ‘n kommersiële X-straaldigt-heidskandeerder, metings van voginhoud, groeiringwydtes, deformasie, akoestiese frekwensie en die bepaling van styfheid met behulp van ‘n meganiese gradeerder. Die data van die X-straalskandeerder is gebruik om ‘n aantal kwasverwante veranderlikes vir elke plank te bereken. Visuele gradering is op alle planke uitgevoer ooreenkomstig met die SANS 1783-2 (2005) spesifikasies vir strukturele hout deur ‘n gesertifiseerde gradeerder. Die hout is in twee groepe opgedeel vir destruktiewe toetse, een vir buigtoetse en een vir trektoetse, ooreenkomstig met die SANS 6122 (1994) metode vir binnegraadse toetse. As gevolg van die monsternemingsmetodiek wat gevolg is, is daar effektief gebruik gemaak van ‘n lukrake plasing van defekte met betrekking tot die las-aanwendingsposisie. Die modulus van elastisiteit (MOEedge), buigsterkte (MOR) en treksterkte is deur middel van destruktiewe toetsresultate bepaal. Die studie het aangetoon dat die MOEedge van gesaagde hout aansienlik minder as die vereiste van die huidige nasionale standaard (SANS 10163-1) is vir al die visuele en meganiese grade. Die gemiddelde MOEedge van die visueel-gegradeerde S5 planke was omtrent 30% laer as vereis. Die 5de persentiel waardes vir buigsterkte van alle visuele en meganiese grade was hoër as die vereiste waardes soos voorgeskryf deur SANS 10163-1. Die 5de persentiel waardes vir treksterkte van alle visuele en meganiese grade was gelykstaande aan wat vereis word deur SANS 10163-1. Korrelasies tussen MOE, gemeet op die wydte sy (MOEflat), en MOE, gemeet op die diktesy (MOEedge), asook die korrelasies van beide MOEedge en MOEflat met MOR van die planke was laer as verwag. Dinamiese MOE (MOEdyn), wat bereken was vanaf die akoestiese frekwensie resultate, is vasgestel as die beste enkele indikator van MOEedge, MOR en treksterkte. Meervuldige regressie analise het aangetoon dat ‘n kombinasie van MOEdyn, digtheid en kwasparameters gebruik kan word om die voorspelbaarheid van sommige van die sterkte- en styfheids eienskappe van die hout te verbeter. Daar word aanbeveel dat ‘n omvattende studie gedoen word op die strukturele gradering van SA Dennehout, wat insluit (1) ‘n analise van die markbehoeftes in terme van die sterkte- en styfheids eienskappe van hout, (2) binnegraadse toetsing van ‘n verteenwoordigende monster strukturele hout in Suid Afrika, en (3) die hersiening van standaarde in gebruik in Suid Afrika om die strukturele gradering van hout te reguleer.
28
CARVALHO, GILBERTO. "Aplicação da radiação gama na determinação de parâmetros físicos em madeiras". reponame:Repositório Institucional do IPEN, 2013. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10603.
Texto completoResumen
Made available in DSpace on 2014-10-09T12:42:23Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T14:01:46Z (GMT). No. of bitstreams: 0
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
29
Fu, Jiawei. "Identification of corneal mechanical properties using optical tomography and digital volume correlation". Thesis, Loughborough University, 2014. https://dspace.lboro.ac.uk/2134/14894.
Texto completoResumen
This work presents an effective methodology for measuring the depth-resolved 3D full-field deformation of semitransparent, light scattering soft tissues such as vertebrate eye cornea. This was obtained by performing digital volume correlation on optical coherence tomography volume reconstructions of silicone rubber phantoms and porcine cornea samples. Both the strip tensile tests and the posterior inflation tests have been studied. Prior to these tests, noise effect and strain induced speckle decorrelation were first studied using experimental and simulation methods. The interpolation bias in the strain results has also been analyzed. Two effective approaches have been introduced to reduce the interpolation bias. To extract material constitutive parameters from the 3D full-field deformation measurements, the virtual fields method has been extended into 3D. Both manually defined virtual fields and the optimized piecewise virtual fields have been developed and compared with each other. Efforts have also been made in developing a method to correct the refraction induced distortions in the optical coherence tomography reconstructions. Tilt tests of different silicone rubber phantoms have been implemented to evaluate the performance of the refraction correction method in correcting the distorted reconstructions.
30
Qi, Hucheng. "Leaching, hydration and physical-mechanical properties of spent chromated copper arsenate (CCA)-treated wood-cement composites". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/MQ58808.pdf.
Texto completo
31
Grotkopp, Ingo. "Influence of water on the mechanical properties of wood investigated using X-ray and neutron scattering". [S.l.] : [s.n.], 2006. http://e-diss.uni-kiel.de/diss_1838/d1838.pdf.
Texto completo
32
Zhao, Xuefeng. "Pointwise identification of elastic properties in nonlinear heterogeneous membranes, and application to soft tissues". Diss., University of Iowa, 2009. https://ir.uiowa.edu/etd/222.
Texto completoResumen
Identifying the elastic properties of heterogeneous materials has long been a very challenging problem both theoretically and experimentally. When it comes to biological tissues, this task is even more difficult since biological tissues generally exhibit substantial anisotropic behavior. Moreover, identification is often required to be performed in the service condition of living human tissues and organs, i.e., in vivo. Presently, a method capable of performing such tasks is lacking.
The primary goal of this study is to fill this gap by developing a novel experimental method, termed as pointwise identification method (PWIM), for delineating the elastic properties in nonlinear heterogeneous membranes. Fundamentally, the method hinges on a unique feature of membrane equilibrium problems, that is, wall stress can be determined from equilibrium consideration alone (static determinacy). Thanks to the static determinacy, membrane wall stress can be computed numerically by using finite element inverse elastostatics method (FEIEM), and depends minimally on the constitutive model.
In PWIM, an inflation test is conducted for the target membrane with a series of tracking markers, and a series of deformed configurations are recorded by using appropriate motion tracking techniques. Subsequently, the pointwise stress distribution in each deformed configuration can be acquired independently by applying FEIEM, whereas the corresponding strain distribution can be determined from the deformation relative to the reference configuration which contains implicitly the elastic properties of the material. Consequently, the elastic properties at every material point can be extracted by fitting an appropriate constitutive model to the pointwise stress-strain data pairs.
In this work, we have validated the method for nonlinear isotropic and anisotropic materials through numerical simulations on a patient-specific cerebral aneurysm model, developed an experimental system and validated the method experimentally by conducting an inflation test on a rubber balloon, and conducted a test on a rabbit urinary bladder. The situation of the global stress-free configuration being unknown was considered numerically by employing a concept of local stress-free configuration. In this regard, the method holds the promise of identifying in vivo the elastic properties of membrane-like living organs, e.g., cerebral aneurysms, using medical images upon the availability of powerful image registration techniques.
33
Ragauskas, Paulius. "Identification Of Elastic Properties Of Layered Composite Materials". Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2010. http://vddb.laba.lt/obj/LT-eLABa-0001:E.02~2010~D_20101119_134738-62490.
Texto completoResumen
In this thesis the problems of identification accuracy of elastic properties of materials are examined. The main object of study is samples of various materials and their elastic properties. This is an important subject of theoretical studies of various materials. The main thesis objective is to create an effective technology for precise identification of all the elastic characteristics of the sample. The de-veloped algorithms are to be applied in the material manufacturing industry. Thesis also aims at exploring accuracy and sensitivity of the identification of elastic properties of materials.
The paper deals with a number of objectives: 1) to optimize the geometric parameters of the sample striving for more accurate identification results of elas-tic properties; 2) to identify mode shapes of sample and regulate their place in spectrum of eigenvalues in order to minimize the distortion of the objective function; 3) to create the implementation algorithms of proposed technologies and verify their capabilities experimentally. The first task is formulated taking into account the relatively high level of identification error of elastic properties of composite materials. The second objective relates to distortion of the objec-tive function in the process of updating the mathematical model with the pre-sumed elastic characteristics of material.
The thesis is composed of four chapters, the summary of results, the list of literature and the list of author’s publications on the topic... [to full text]Disertacijoje nagrinėjamos medžiagų tamprumo rodiklių identifikavimo tikslumo problemos. Pagrindinis tyrimo objektas yra įvairių medžiagų bandiniai, jų tamprumo rodikliai. Šis objektas yra svarbus įvairių medžiagų teoriniams tyrimams. Pagrindinis disertacijos tikslas yra sukurti efektyvią technologiją, leidžiančią pakankamu tikslumu surasti visus bandinio tamprumo rodiklius. Sukurtų algoritmų taikymo sritis yra medžiagų gamybos pramonė. Disertacijoje tiriamas siūlomos technologijos tikslumas ieškant įvairių medžiagų tamprumo rodiklių. Darbe sprendžiami keli pagrindiniai uždaviniai: optimizuojami bandinio geometriniai parametrai siekiant tikslesnių tamprumo rodiklių identifikavimo rezultatų; atpažįstamos bandinio modų formos ir reguliuojama jų vieta tikrinių reikšmių spektre siekiant sumažinti tikslo funkcijos iškraipymus; sukuriami pasiūlytų technologijų įgyvendinimo algoritmai ir bandymais patikrinamos jų galimybės. Pirmasis uždavinys suformuluotas atsižvelgiant į palyginti didelę kompozitinių medžiagų tamprumo rodiklių identifikavimo paklaidą. Antrasis siejasi su tikslo funkcijos iškraipymu atnaujinant matematinį medžiagos modelį spėjamais tamprumo rodikliais. Disertaciją sudaro keturi skyriai, rezultatų apibendrinimas, naudotos literatūros ir autoriaus publikacijų disertacijos tema sąrašai. Įvadiniame skyriuje aptariamas problemos aktualumas, tyrimo objektas, formuluojamas darbo tikslas bei uždaviniai, aprašoma tyrimų metodika, darbo mokslinis naujumas, darbo rezultatų... [toliau žr. visą tekstą]
34
Sánchez, Vivas Lorena. "Bamboo as a Sustainable Engineering Material: Mechanical Properties, Safety Factors, and Experimental Testing". Scholar Commons, 2019. https://scholarcommons.usf.edu/etd/7925.
Texto completoResumen
With exponential global population growth occurring and associated environmentally destructive consumption of natural resources, alternative materials that are fast growing and sustainable are being sought out to satisfy human needs. One material that is fast growing and sustainable that can be used to meet most basic needs of humans (i.e. shelter, food, tools) is the plant bamboo, of the grass family Poaceae. Bamboo was used in the past by native peoples who lived in the environment where bamboo natively grows (all continents except Europe and Antarctica) with proven success for uses such as shelter, piping, tools, wells, food, fencing, baskets and much more. These practices were mostly abandoned and deemed obsolete due to the introduction of long lasting ‘modern’ building materials of steel and concrete which gained popularity in the 1800s. Now, in the current century with much advancement in science, technology, and education, humanity is reconsidering many practices and returning to more ancient practices and ways that are better for human health, the environment, and overall sustainability.
These environmental considerations are drivers of this research, which focuses on how to use bamboo for engineering applications. First, in order to use a material for engineering and design applications, a material must be destructively tested to attain material property values. Therefore, a critical examination of the bamboo mechanical property values published literature was performed. It was found that although many scientists all over the world have been working on mechanical property testing of bamboo, their results have been published in different journals, in different languages, and had not yet been aggregated and compared. This led to the first study in this work that analyzed mechanical property data from 43 bamboo peer-reviewed publications written in English, Spanish, and Portuguese (the three main languages in which bamboo literature is published). This study focused on aggregating mechanical property values, establishing a range of values for each property as well as an average, and correlating the difference in property values to bamboo variables stated in bamboo literature (age, bamboo species, density, moisture content, post-harvest treatment, and testing standard employed). The five mechanical properties reviewed were: shear strength, compressive strength, tensile strength, bending strength / modulus of rupture (MOR), and modulus of elasticity (MOE) and their average values were 9 MPa, 52 MPa, 159 MPa, 120 MPa, and 16 GPa, respectively. Although a thorough graphical set of analyses were performed attempting to correlate the difference in mechanical property values to the previously listed variables, and only main variables found to influence strength values were moisture content and specific testing standard employed.
The results of the high range of mechanical property values with no variable with which to separate the results to lower the range, led to the second part of the research. It incorporated the high range of values reported in the literature but was able to establish safety factors and reduction factors alongside corresponding failure rates. This work allows for a designer to use bamboo culms choosing a failure rate he/she deems appropriate for structural bamboo construction. The analyses in this work were performed using Allowable Stress Design (ASD) and Load and Resistance Factor Design (LRFD) equations applied to bamboo as well as Monte Carlo statistical analyses for verification. The raw data and statistically analyzed data of 25 publications were used for this analysis, yielding 3806 strength test values (shear strength, compressive strength, bending strength / modulus of rupture, and tensile strength). Shear strength safety factors ranged from 1.38-3.58 for failure ratios from 1:6-1:25000; compressive strength from 1.30-2.79; bending strength from 1.43-4.03; tensile strength from 1.66-7.43. No singular safety factor is suggested for design as that is due to the judgment of the designer of what failure ratio he/she deems appropriate for the specific application.
Although many compression tests have been performed on bamboo, there are no known tests which destructively test bamboo after an extended period of time after harvesting (more than ~3 months). This experiment conducted a field experiment to test the functionality of using bamboo for the application of installing bamboo wells to provide groundwater. The bamboo tested in the third part of the study was of two species, Dendrocalamus giganteus and Dendrocalamus asper half of which were 1) air-dried in a laboratory for 3.5 years and the other half of which was 2) inserted in the ground as bamboo wells. The bamboo culms (or poles) had been separately treated in three different ways right after cutting: 1/3 with a borax and boric acid solution (most conventional treatment in the industry), 1/3 with coconut oil (experimental treatment in the literature), and 1/3 air-dried, a non-treated control. Bamboo wells are said to be used in ancient times as well as in more recent applications in the 1990s in India by small scale farmers. The publication of bamboo well studies have been very few and nearly no scientific analyses had been performed on them. Therefore, six bamboo wells were assembled and installed at the University of South Florida Geopark, the first of their kind in the U.S. These wells were half of species D. giganteus and half of species D. asper and also treated individually using the three different treatments described above. The wells were monitored for pH and presence of leached boron for a 3.5-year monitoring period and then removed. Upon removal, the bamboo well casings were examined for molds present as well as by mechanical compression testing to assess degradation in comparison to each other (of different treatments) and to air-dried control samples maintained in the laboratory for 3.5 years. The mold fc. Acrodictys was observed to cover the entire inner portion of the bamboo (inner diameter), from the surface level up to the water table. The lab air-dried control samples had compression strength and compressive modulus of elasticity values correlating to those found in the literature, 44-90 MPa (72 MPa average) and 15-31 GPa, respectively. Removed well samples exhibited compressive strengths and compressive modulus of elasticity values of 22-61 MPa (39 MPa average) and 7-25 GPa, respectively. This study revealed that bamboo wells were feasible and although their compressive strengths lowered by around a half after being in the ground for 3.5 years, their compressive strength and compressive modulus of elasticity values were still in the range of bamboo tested in the literature.
35
SEVERIANO, LUCIO C. "Estudo do efeito da radiacao gama sobre algumas propriedades fisico-mecanicas de madeiras usadas em patrimonios artisticos e culturais brasileiros". reponame:Repositório Institucional do IPEN, 2010. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9543.
Texto completoResumen
Made available in DSpace on 2014-10-09T12:27:51Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T14:04:49Z (GMT). No. of bitstreams: 0
Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
36
Jeffries, Thomas Mason. "Relationships of growth rate and mechanical properties in sweetgum, Liquidambar styraciflua". Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/31225.
Texto completoResumen
Sweetgum, Liquidambar styraciflua, is a diffuse-porous hardwood occurring in the southeastern United States. In this observational study, trees from two plantations of sweetgum were evaluated for mechanical properties. The two plantations were similar in age, soil type, competition control, and water availability, but differed in nutrient availability, growing season, and growth rate. Three trees representing different crown classes were removed from both plantations. Each tree was sampled for compression strength parallel to grain along the height of the merchantable stem. Oven-dry specific gravity was then calculated for each sample. The results indicate that young sweetgum trees grow weaker wood than mature trees. It was observed that dominant trees were stronger and denser than other trees. Denser wood was formed in the plantation with the shortest growing season and smallest growth rate. Three of six trees showed significant correlations of strength and stiffness with height in the tree.Master of Science
37
Johnson, Richard Kwesi. "Wetlaid Cellulose Fiber-Thermoplastic Hybrid Composites - Effects of Lyocell and Steam Exploded Wood Fiber Blends". Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/43767.
Texto completoResumen
Fiber hybridization involves the blending of high and low performance fibers in a common matrix to yield a composite with a balance of properties that cannot be achieved by using either fiber alone. In this study, the random wetlay process was used as a compounding method to investigate the effects of fiber hybridization on the mechanical, viscoelastic, and sorption characteristics of steam-exploded wood (SEW) and lyocell (high performance regenerated cellulose) fiber-reinforced polypropylene (PP) composites. The two fiber types were blended in varying proportions within a fixed total fiber content of 50 wt. % and compared with non-hybrid lyocell- and SEW-PP controls.
Using PP matrix as basis, it was observed that moduli of all composites generally increased with increasing lyocell concentration, ranging from a minimum 66 % for SP 50 (SEW/PP control) to a maximum 233 % for LP 50 (lyocell/PP control). Ultimate strengths on the other hand, declined for SP 50 but increased with the inclusion of lyocell fibers.
Comparisons of hybrid (having 5 - 20 wt % lyocell) with non-hybrid (having 25 - 50 wt. % lyocell) composites revealed a surprisingly greater strength and modulus-building efficiency (by as much as 2.6 times) in the hybrid composites. This observation indicated possible synergism between lyocell and SEW. Analyses of composite property gains as a function of fiber cost also showed greater cost benefits (highest for tensile modulus) in favor of hybridization.
The advantages of fiber hybridization on composite properties were again evident under dynamic mechanical analysis where no significant differences in the storage moduli were found between a hybrid composite with 20 wt. % lyocell and a non-hybrid composite with 50 wt. % lyocell loading. Application of the time-temperature superposition principle (TTSP) made it possible to predict storage moduli over extended frequencies for PP and its composites. Comparison of shift factor versus temperature plots revealed decreasing relaxation times of PP with increasing lyocell concentration, which indicated that PP interacted better with lyocell than with SEW fibers.
Finally, it was observed from sorption tests that hybrid composites absorbed less moisture than non-hybrid counterparts of either fiber type. The reasons for this observation were not apparent. It is however possible that moisture transport mechanisms within the composites may have been modified as a result of hybridization.Master of Science
38
Dias, Antonio Alves. "Estudo da solicitação de compressão normal às fibras da madeira". Universidade de São Paulo, 1994. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-10022009-155300/.
Texto completoResumen
Este trabalho apresenta um estudo teórico e experimental a respeito da solicitação de compressão normal às fibras da madeira, para a qual não é previsto ensaio para caracterização, atualmente, na NBR-6230 (Ensaios físicos e mecânicos de madeiras). Foram abordados aspectos referentes à geometria do corpo-de-prova, velocidade de aplicação de carga, direção do carregamento em relação aos anéis de crescimento e condições de umidade. Com base nos resultados obtidos, é proposto método de ensaio para caracterização da madeira solicitada por compressão normal às fibras.This work presents an experimental study about compression perpendicular to the grain in wood, for which characterization test is not indicated by NBR-6230 (Physical and mechanical test in wood). Several points were discussed: specimen geometry, speed of testing, direction of loading referred to the growth rings and moisture conditions. Based on the experimental data, a testing procedure is proposed in order to be employed in wood characterization in compression perpendicular to the grain.
39
Pinheiro, Roberto Vasconcelos. "Influência da preservação contra a demanda biológica em propriedades de resistência e de elasticidade da madeira". Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-04042016-161837/.
Texto completoResumen
A madeira pode ser renovável, de fácil obtenção e custo competitivo, tornou-se com o decorrer do tempo, um dos materiais pioneiros na contrução civil. Porém, no Brasil, o emprego indiscriminado e descontrolado ao longo dos anos, principalmente na construção civil, proporcionou uma redução drástica das florestas nativas das regiões Sul/Sudeste. Conseqüentemente, passou a ser necessária a utilização de madeiras alternativas, e, entre elas, pode-se citar as espécies do gênero Eucalytpus e Pinus. Sabendo-se que tais espécies são altamente susceptíveis à demanda biológica, é indispensável a adoção de medidas preventivas visando melhorar a sua durabilidade. Dentre algumas medidas possíveis, a preservação através da introdução de produtos químicos por processos industriais é a mais eficaz. Uma das questões levantadas a respeito do citado procedimento reporta à sua influência no comportamento intrínseco da madeira, no tocante às suas propriedades mecânicas. Portanto, a partir daí, este projeto tem o objetivo de verificar a influência da preservação química (processo e produto) sob vácuo-pressão contra a demanda biológica, por meio de preservativos hidrossolúveis (tipo CCA e CCB), nas propriedades de resistência e de elasticidade das espécies de Eucalipto Grandis (Eucalyptus grandis) e Pinus Elliottii (Pinus elliottii). Usando apenas o produto CCA, quatro espécies nativas: Angelim (Vatárea sp), Ipê (Tabebuia sp), Copaíba (Copaifera sp) e Jatobá (Hymenaea sp). Como subproduto da pesquisa, foram obtidas algumas relações entre os valores da resistência característica à compressão e ao cisalhamento paralelo às fibras, bem como entre os valores da resistência característica à compressão e a tração paralela às fibras. Também foi objeto de estudo , em uma fase preliminar, a análise da possível variação, ao longo do comprimento da peça, da propriedade de resistência e de rigidez (elasticidade) ) à compressão paralela às fibras, uma vez mantida fixa a posição nos rios. No final, foram obtidos alguns resultados relevantes para a relação entre os valores de compressão paralela da madeira sem preservação e a tratada quimicamente, principalmente referente ao Pinus Elliottii. Nesta espécie, para o tratamento realizado com o CCA, o acréscimo foi de 17% (retenção de 10 kg/m3), enquanto o CCB (retenção em torno de 40 kg/m3) levou a um aumento de 55% em média. Outros resultados passíveis de comentários, referem-se às relações entre propriedades características de cisalhamento e compressão (preservados e sem preservação) para todas as espécies estudadas. Da maneira geral, os valores foram bem superiores àqueles estabelecidos pela NBR 7190/97, alcançando patamares em torno de 50% para as espécies de reflorestamento e 90% para as espécies nativas (exceto para o Ipê). De forma sucinta, pode-se concluir que a preservação química industrial é de extrema relevância, principalmente por não reduzir e, em alguns casos até aumentar os valores das propriedades mecânicas estudadas, além de ser um método comprovado e eficaz contra a biodeterioração.As time goes bye, wood had been one of the main materials in building construction, because it\'s renovation, easy obtainment ans competitive cost. In Brazil, indiscriminate employing during last decades, particularly in South and Southwest regions, reduced drastically the native species offer. The use of alternative species, as those from Pinus and Eucalyptus genera, became necessary. As the cited species are so susceptible to biological demand, to take prevent procedures to increase natural durability in indispensable. Among these procedures, chemical preservation under pressure in industrial plans can be considered very efficient. One of the questions related to chemical preservation is its influence in mechanical behavior of treated wood. So, the aim of the work is to determine the influence of chemical preservation under pressure (with preservative substances as CCA and CCB) in strength and stiffness properties of Eucalipto Grandis (Eucalyptus grandis) and Pinus Elliottii (Pinus elliottii). The influence do CCA preservative was studied to four tropical essences: Angelim (Vatairea sp), Ipê (Tabebuia sp), Copaíba (Copaifera sp) and Jatobá (Hymenaea sp). At least, comparative values of mechanical properties of natural and preserved wood are presented.
40
Königsmann, Martin. "Modification of Wood Surfaces via controlled Polymerization Methods". Doctoral thesis, Niedersächsische Staats- und Universitätsbibliothek Göttingen, 2018. http://hdl.handle.net/11858/00-1735-0000-002E-E4BA-1.
Texto completo
41
Zandi, Mohammad Damous. "Study and characterization of mechanical properties of wood-PLA composite (Timberfill) material parts built through fused filament fabrication". Doctoral thesis, Universitat Politècnica de Catalunya, 2020. http://hdl.handle.net/10803/669587.
Texto completoResumen
This research is based upon the additive manufacturing (AM) technology which aims to study the mechanical properties of innovative commercial wood-PLA composite material (Timberfill) and characterize its behavior. Specifically fatigue, tensile, and flexural tests are performed and the results are evaluated to conclude this issue. To manufacture the experimental samples one of the most common techniques named fused filament fabrication (FFF) is applied, consequently the influence of manufacturing parameters on the mechanical properties have been considered. For this reason some of the most influential printing parameters in different levels are selected and have been combined together to manufacture the samples in a wide range of building conditions. To avoid manufacturing a large number of specimens, a design of experiments (DoE) through Taguchi orthogonal arrays is designed and the influence of the factors have been analyzed performing an analysis of variance (ANOVA). As a conclusion the optimal combination of the parameters and levels have been obtained for each one of the applied mechanical tests and higher values of responses have been derived from these set of parameters. Since the above mentioned material is composite of wood fibers with PLA, all of the obtained results are compared to the pure PLA to find the effectiveness of this composition.
In the other side tensile and flexural tests have been applied on solid Timberfill specimens manufactured through injection molding to investigate the differences between this technology and additive manufacturing. These investigations resulted that mechanical resistances of the printed samples were lower than injected ones which the solidity percentage could be main reason of this effect.
Additionally the flexural strength of the material have been simulated and compare to the experimental results. The achieved deformation behavior curves validate the experimental test and that would be one of the main conclusions of this research.Esta investigación se basa en la tecnología de fabricación aditiva (AM) y tiene como objetivo estudiar las propiedades mecánicas y caracterizar el comportamiento de un material comercial innovador, compuesto de PLA con fibras de madera (Timberfill). Específicamente, se realizan pruebas de fatiga, tracción y flexión y se evalúan los resultados para concluir sobre los mismos. Para fabricar las muestras experimentales se aplica una de las técnicas más comunes llamadas fabricación de filamentos fundidos (FFF), y se ha considerado la influencia de los parámetros de fabricación en las propiedades mecánicas de las mismas. Por esta razón, se han seleccionado algunos de los parámetros de impresión más influyentes en diferentes niveles y se han combinado para fabricar las muestras en una amplia gama de condiciones de construcción. Para evitar la fabricación de una gran cantidad de muestras, se ha utilizado un diseño de experimentos (DoE) a través de matrices ortogonales de Taguchi y se ha analizado la influencia de los factores realizando un análisis de varianza (ANOVA). Como conclusión, se ha obtenido la combinación óptima de los parámetros y niveles para cada una de las pruebas mecánicas realizadas y se han detectado los valores más altos de respuestas de éstos. Dado que el material mencionado anteriormente es un compuesto de PLA con fibras de madera, todos los resultados obtenidos se comparan con el PLA puro para encontrar la efectividad de esta composición. Por otro lado, se han realizado también pruebas de tracción y flexión a muestras sólidas de Timberfill fabricadas mediante moldeo por inyección para investigar las diferencias entre esta tecnología y la fabricación aditiva. Los resultados muestran que la resistencia mecánica de las muestras impresas es más bajas que las inyectadas, por lo que el porcentaje de solidez podría ser la razón principal de este efecto. Además, la resistencia a la flexión del material se ha simulado y comparado con los resultados experimentales. Las curvas de comportamiento de deformación logradas validan la prueba experimental lo cual es una de las principales conclusiones de esta investigación.
Aquesta investigació es basa en la tecnologia de fabricació additiva (AM) i té com a objectiu estudiar les propietats mecàniques i caracteritzar el comportament d'un material comercial innovador, format de PLA amb fibres de fusta (Timberfill). Específicament, es realitzen proves de fatiga, tracció i flexió i s'avaluen els resultats per concloure sobre els mateixos. Per fabricar les mostres experimentals s'aplica una de les tècniques més comunes anomenada fabricació de filaments fosos (FFF), i s'ha considerat la influència dels paràmetres de fabricació en les propietats mecàniques de les mateixes. Per aquesta raó, s'han seleccionat alguns dels paràmetres d'impressió més influents en diferents nivells i s'han combinat per fabricar les mostres en una àmplia gamma de condicions de construcció. Per evitar la fabricació d'una gran quantitat de mostres, s'ha utilitzat un disseny d'experiments (DoE) a través de matrius ortogonals de Taguchi i s'ha analitzat la influència dels factors realitzant una anàlisi de variància (ANOVA). Com a conclusió, s'ha obtingut la combinació òptima dels paràmetres i nivells per a cadascuna de les proves mecàniques realitzades i s'han detectat els valors més alts de respostes d'aquests. Atès que el material esmentat anteriorment és un compost de PLA amb fibres de fusta, tots els resultats obtinguts es comparen amb el PLA pur per trobar l'efectivitat d'aquesta composició. D'altra banda, s'han realitzat també proves de tracció i flexió a mostres sòlides de Timberfill fabricades mitjançant el procediment d’injecció per investigar les diferències entre aquesta tecnologia i la fabricació additiva. Els resultats mostren que la resistència mecànica de les mostres impreses és més baixes que les injectades, de manera que el percentatge de solidesa podria ser la raó principal d'aquest efecte. A més, la resistència a la flexió del material s'ha simulat i comparat amb els resultats experimentals. Les corbes de comportament de deformació assolides validen la prova experimental la qual cosa és una de les principals conclusions d'aquesta investigació.
42
Dubey, Manoj Kumar. "Improvements in stability, durability and mechanical properties of radiata pine wood after heat-treatment in a vegetable oil". Thesis, University of Canterbury. School of Forestry, 2010. http://hdl.handle.net/10092/3856.
Texto completoResumen
Radiata pine is a major plantation grown wood in the Southern hemisphere, but has inferior dimensional stability and low durability compared to other commercial species and the improvement of these features is the focus of this thesis.
Specifically this thesis examines the dimensional stability, durability and mechanical properties of radiata pine after heat-treatment (160-210°C) in linseed oil. Changes in colour, micro-structure and chemistry with heat-treatment were studied. To optimise the treatment results, oil heat-treatment of wood was also carried out after thermo-mechanical compression of wood and the effect of the prior thermo-mechanical compression on stability, durability and mechanical properties were examined.
The oil heat-treated wood turned uniformly darker in colour. The hydrophobicity (Water Repellence Efficiency-WRE up to 30%), dimensional stability (Ant-Swelling Efficiency-ASE up to 60%) and fungal resistance (up to 36%) were improved with the extent of the changes mainly depending on treatment temperature. However, the mechanical properties of oil heat-treated wood were reduced compared to the untreated control group. Accelerated UV weathering tests have shown that the oil heat-treated wood retained its colour and dimensional stability better than the untreated wood (the control group).
The cell wall of treated wood was intact and no distinct structural changes were observed even at the most severe treatment (210°C for 6 hrs).The treatment resulted in changes to the wood chemical constituents, mainly the degradation of hemicelluloses which is believed to be principal reason for alterations in wood properties.
A study of the effect of prolong heating on the linseed oil showed an increase in viscosity with heating time which in turn reduced the oil uptake and water repellency of treated wood. However, no significant difference in the colour and dimensional stability of the treated wood was noticed with oil of different heating ages. Oil absorbed by the wood during heat treatment was removed by organic solvent extraction and its contribution to the weight percentage change and moisture related properties were evaluated. The oil uptake percentage, determined by organic solvent extraction, was greater than the weight percentage loss that was deduced to occur during the heat treatment phase, which was attributed to mass losses or thermal degradation of wood constituents. Moisture excluding efficiency decreased after removal of the oil from treated wood, which suggested that the hydrophobicity of treated wood is affected by oil absorbtion. The influence of the post-treatment cooling period on properties of treated wood was studied separately. Oil uptake increased substantially with the post-treatment cooling time which in turn affected the hydrophobicity of treated wood although this effect was less important to dimensional stability.
The loss of mechanical properties due to heat-treatment was successfully countered by thermo-mechanical compression of wood prior to the oil heat-treatment. The wood was compressed to 39% of its original thickness without any visible surface checks and cracks. Spring back and compression set recovery in densified wood decreased after oil heat-treatment. This combination treatment also resulted in improved fungal resistance compared to untreated wood.
From this research, it is concluded that oil heat-treatment of radiata pine wood can improve its dimensional stability and durability obviating the need to introduce any persistent toxic chemicals. Thermo-mechanical densification of wood prior to oil heat-treatment can countered the loss of mechanical properties due to heat-treatment. The heating oil can be re-used in subsequent treatments and oil uptake can be minimised by limiting the post-treatment cooling time without any significant effect on the dimensional stability of treated wood.
43
Nordqvist, Petra. "Exploring the Wood Adhesive Performance of Wheat Gluten". Doctoral thesis, KTH, Ytbehandlingsteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-94883.
Texto completoResumen
The increasing environmental concern has reawakened an interest in materials based on renewable resources as replacement for petroleum-based materials. The main objective of this thesis was to explore plant proteins, more specifically wheat gluten, as a binder in wood adhesives intended for typical solid wood applications such as furniture and flooring. Alkaline and acidic dispersions of wheat gluten were used as wood adhesives to bond together beech wood substrates. Soy protein isolate was used as a reference. The tensile shear strengths of the substrates were measured for comparison of bond strength and resistance to cold water. AFM in colloidal probe mode was used to investigate nanoscale adhesion between cellulose and protein films. Wheat gluten was divided into the two protein classes; glutenins and gliadins, and their adhesive performance was compared with that of wheat gluten. Heat treatment and mild hydrolysis were investigated as means for improving bonding performance of wheat gluten. The treated wheat gluten samples were analysed by SE-HPLC and 13C-NMR to correlate molecular size distribution and structural changes with bonding performance. Soy protein isolate is superior to wheat gluten, especially in regards to water resistance. However, the bond strength of wheat gluten is improved when starved bond lines are avoided. The AFM analysis reveals higher interfacial adhesion between soy protein isolate and cellulose than between wheat gluten and cellulose. These results partly explain some of the differences in bonding performance between the plant proteins. Soy protein isolate contains more polar amino acid residues than wheat gluten and possibly interacts more strongly with cellulose. Furthermore, the bond performances of wheat gluten and glutenin are similar, while that of gliadin is inferior to the others, especially regarding water resistance. The extent of penetration of the dispersions into the wood material has a large impact on the results. The bonding performance of gliadin is similar to the others when over-penetration of the dispersion into the wood material is avoided. Moreover, the bond strength of the wheat gluten samples heated at 90°C was in general improved compared to that of wheat gluten. A small improvement was also obtained for some of the hydrolyzed wheat gluten samples (degree of hydrolysis: 0-0.6 %). The improvements in bonding performance for the heat treated samples are due to polymerization, while the improvements for the hydrolyzed samples are due to denaturation. The 13C-NMR analysis of the treated samples confirms some degree of denaturation.QC 20120514
44
Crafford, Philippus Lodewicus. "An investigation of selected mechanical and physical properties of young, unseasoned and finger-jointed Eucalyptus grandis timber". Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/80072.
Texto completoResumen
Thesis (MScFor)--Stellenbosch University, 2013.ENGLISH ABSTRACT: South Africa is a timber scarce country that will most probably experience a shortage of structural timber in the near future. In this study the concept of using young finger‐jointed Eucalyptus grandis timber was evaluated for possible application in roof truss structures while the timber is still in the green, unseasoned state. 220 finger‐jointed boards of cross‐sectional dimension 48 x 73 mm and 36 x 111 mm timber, cut from 5‐18 year old Eucalyptus grandis trees were obtained from Limpopo province, South Africa. The boards were manufactured using a polyurethane (PU) adhesive at moisture content levels above fibre saturation point and no drying was performed. The objectives of this study were to determine various mechanical and physical properties of this finger‐jointed product. More specifically (1) to determine the strength and stiffness potential of the product in the wet and the dry condition, (2) to evaluate physical properties such as density, warp, checking and splitting, (3) to evaluate potential indicator properties to be used as structural grading parameters, and (4) to compare the flexural properties to the current SA pine resource and SANS structural grade requirements. The boards were divided into two groups of the same size, which constituted the wet and the dry samples. Each sample was further separated into six different groups for testing the different strength and stiffness properties. The dry group was stacked in a green‐house for nine weeks until equilibrium moisture content was reached. Afterwards selected physical properties such as warp, checking and splitting were assessed. Destructive testing was conducted on the boards and the results were used to determine various mechanical properties. Finally, each board was assessed for density and moisture content (MC) values. The study showed that the young finger‐jointed Eucalyptus grandis timber had very good flexural properties. Both mean modulus of elasticity (MOE) and modulus of rupture (MOR) 5th percentile strength values for wet and dry boards complied with the current SANS 10163‐1 (2003) requirements for grade S7.The values of tensile perpendicular to grain and compression perpendicular to grain strength did not conform to SANS requirements for grade S5. The other strength properties for the wet and dry groups complied with one of the three SANS structural grades. The 5 year old (48 x 73 mm) boards’ showed significantly higher levels of twist and checking compared to 11 year old boards of the same dimension. Only 46.3% of the finger‐jointed products conformed to the density requirements in SANS 1783‐2 (2004) for grade S7. There was a significant difference in density between the three age groups (5, 11 and 18 years) presented in this study. The variation in both MOE and MOR values of the fingerjointed product proved to be significantly lower in comparison to currently used SA pine sources. Based on the results from this study the concept of producing roof trusses from wet, unseasoned and finger‐jointed young Eucalyptus grandis timber has potential. However, additional research on a number of issues not covered in this study is still required for this product including full scale truss evaluations, proof grading, PU adhesive evaluation at elevated temperatures, nail plate load capacity, and the possible need for chemical treatment of the product against Lyctus beetles.
AFRIKAANSE OPSOMMING: Suid Afrika is ‘n land wat waarskynlik ‘n tekort aan strukturele hout sal ervaar in die nabye toekoms. In hierdie studie word die gebruik van jong gevingerlasde Eucalyptus grandis hout vir die moontlike gebruik in dakstrukture, terwyl nat en ongedroog, ondersoek. 220 gevingerlasde planke van deursnit 48 x 73 mm en 36 x 111 mm gesaag van 5‐18 jaar‐oue Eucalyptus grandis bome en afkomstig van die Limpopo provinsie in Suid Afrika, is gebruik. Die produk is vervaardig met poli‐uretaan (PU) lym uit planke met vog inhouds vlakke bo veselversadigingspunt. Die doelwit van hierdie studie was om verskeie meganiese en fisiese eienskappe van die vingerlas produk vas te stel. Meer spesifiek (1) om die sterkte en modulus van elastisiteit (MOE) potensiaal van die vingerlas produk in die nat en droë toestand te analiseer, (2) om die fisiese eienskappe soos digtheid, vervorming, oppervlakbarse en spleting te ondersoek, (3) om potensiële graderingsparameters te evalueer, en (4) om die buigeienskappe van die produk te vergelyk met SA dennehout asook die SANS strukturele graad vereistes. Die planke is verdeel in twee groepe, ‘n nat groep en ‘n droë groep. Elke groep is verder verdeel in ses kleiner groepe soos buig, trek en drukmonsters. Die droë groep was in ‘n kweekhuis geplaas vir nege weke totdat veselversadigingspunt bereik is. Daarna is geselekteerde fisiese eienskappe soos vervorming, oppervlak barse en spleting gemeet. Destruktiewe toetsing is uitgevoer op die planke en die resultate was gebruik om verskeie meganiese eienskappe vas te stel. Laastens is elke plank se digtheid en voggehalte gemeet. Die studie het getoon dat die jong gevingerlasde Eucalyptus grandis hout goeie buigeienskappe het. Beide die gemiddelde MOE en buig sterkte 5de persentiel waardes van die nat en droë groep het voldoen aan die huidige SANS 10163‐1 (2003) vereistes vir graad S7. Die sterkte‐eienskappe van loodregte trekkrag en loodregte druk het nie die vereistes vir SANS graad S5 gemaak nie. Die ander sterkte‐eienskappe van die nat en droë groep het voldoen aan een van die drie SANS strukturele graadvereistes. Die 5 jaar‐oue (48 x 73 mm ) planke het beduidend hoër vlakke van draai‐trek en oppervlakbarste getoon as die 11 jaar‐oue planke van dieselfe dimensie. Slegs 46.3% van die vingerlas produk het voldoen aan digtheidsvereistes vir SANS graad S7. Daar was ‘n beduidende verskil in dightheid tussen die drie ouderdomsgroepe (5, 11 en 18 jaar). Die MOE en buigsterkte‐waardes van die Biligom produk het beduidend laer variasie as huidige SA denne houtbronne getoon. Die resultate verkry in die studie toon dat die konsep om dakkappe te vervaardig van nat, gevingerlasde jong Eucalyptus grandis hout die potensiaal het om suksesvol toegepas te word. Bykomende navorsing oor ‘n aantal faktore wat nie in hierdie studie ingesluit is nie word steeds benodig. Dit sluit in ‘n volskaalse dakkap evaluasie, proefgradering, PU lym evaluasie by hoë temperature, spykerplaat ladingskapasiteit en die moontlike noodsaaklikheid van chemiese behandeling van die produk teen Lyctus kewers, insluit.
45
Rollo, Luciana Cavalcante Pereira. "Tomografia de impulso para estimativa da densidade da madeira". Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/11/11150/tde-16032010-170802/.
Texto completoResumen
Há diversas técnicas que utilizam a passagem de ondas através da madeira para obtenção de informações. Dentre elas destaca-se a tomografia de árvores que reconstrói seções transversais de tronco e galhos. A tomografia de impulso, por sua vez, se baseia na cronometragem da viajem de ondas mecânicas sonoras entre sensores anexados em uma seção transversal da árvore, para cálculo da velocidade da onda e construção da imagem tomográfica. Sabe-se que a velocidade de passagem das ondas mecânicas é determinada pelas propriedades físico-mecânicas da madeira. Em especial: o módulo de elasticidade, a densidade e a umidade. Até o momento, há diversos estudos sobre a correlação entre a velocidade de onda (principalmente ultrassom) e o módulo de elasticidade. Os estudos apresentados a seguir se destacam por avaliar a correlação entre a velocidade de onda mecânica, obtida por tomografia de impulso, e a densidade da madeira, com vistas em utilizá-la como ferramenta na estimativa da densidade. Os diversos métodos consagrados para a determinação da densidade se caracterizam por utilizar amostras de madeira, que em muitos casos são de difícil obtenção. Além de serem executados procedimentos laboratoriais que podem levam até semanas. Dessa forma, no capítulo 2, Conceitos físicos envolvidos na técnica de tomografia de impulso e a relação com a densidade aparente, são feitas algumas considerações sobre os conceitos físicos que explicam o comportamento de ondas mecânicas e apresentada a correlação encontrada entre velocidade de onda mecânica e densidade aparente, a 12% de umidade da madeira, para três espécies de árvores de diferentes densidades (Schizolobium parahyba (Vell.) Blake - Guapuruvu, Eucalyptus saligna Sm. - Eucalipto, Caesalpinia echinata Lam. Pau-Brasil). Os resultados foram bastante satisfatórios, visto que o coeficiente de determinação - R2 da equação geral velocidade de onda mecânica a 12% = 514,89 * densidade aparente a 12% + 312,49 foi igual a 0,9284, altamente significativo pelo teste F a 1%. No capítulo 3, Tomografia de impulso para estimativa da densidade básica da madeira em árvores vivas, são apresentados modelos estatísticos para estimativa da densidade básica da madeira em árvores vivas, por meio da velocidade de onda mecânica. Foram coletados dados a partir de árvores de 10 espécies nativas. As medidas de acurácia (coeficiente de determinação R2, erro médio percentual EMP, e erro aleatório i) permitem afirmar que os modelos são úteis.There are several techniques which use the passage of waves through wood to obtain information. Among them the tomography of trees is emphasized, reconstructing cross sections of trunk and branches. The impulse tomography is based on the timing of mechanical sound wave travelling between sensors attached to a cross section of the tree, to compute wave speed and construction of the tomographic image. It is known that the speed of the passage of mechanical waves is determined by the phisical and mechanical properties of the wood. Specially, eslasticity module, density and moisture content. Until this moment, there are several studies about the correlation between wave speed (mainly ultrasound) and elasticity module. The studies presented next are highlighted because they evaluate the correlation between mechanical wave speed, obtained by impulse tomography, and wood density, with the intention to use it as a tool to estimate density. The several estabilished methods for determining wood density are characterized by using wood samples, in many cases, difficult to obtain. Besides being performed using laboratory procedures which may take even weeks. Therefore, in chapter 2, Physical concepts involved in the impulse tomography method and the relationship with apparent density, there are considerations about physical concepts that explain the behavior of mechanical waves and present the correlation found between mechanical wave speed and apparent density, with 12% moisture content of the wood, to three species of wood with different densities (Schizolobium parahyba (Vell.) Blake - Guapuruvu, Eucalyptus saligna Sm. - Eucalipto, Caesalpinia echinata Lam. Pau-Brasil). The results were very satisfying, since the coeficient of determination - R2 the general equation mechanical wave speed at 12% =514,89 * apparent density at 12% + 312,49 was equal to 0,9284, highly significant regarding F test at 1%. In chapter 3, Impulse tomography for the estimation of basic wood density of live trees, statistical models for estimation are presented to estimate basic wood density in live trees, using mechanical wave speed. Data was collected from trees of 10 native species. The accuracy measurements (coeficient of determination R2, mean percentual error EMP, and random error i) ensure the utility of the models.
46
Lingström, Rikard. "Formation and properties of polyelectrolyte multilayers on wood fibres : influence on paper strength and fibre wettability". Licentiate thesis, KTH, Fibre and Polymer Technology, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4062.
Texto completoResumen
The work in this licentiate thesis examines the adsorption of polyelectrolyte multilayers (PEM) onto wood fibres as a new way to influence the properties of the fibre surfaces and hence the fibres. Fundamental aspects of PEM formation on wood fibres have been studied, and discussed in terms of paper strength and wood fibre wettability.
PEMs have been formed from three different polymer systems: 1) two strong polyelectrolytes (i.e., fully charged over a wide pH range), polydimethyldiallylammonium chloride (PDADMAC) and polystyrene sulphonate (PSS); 2) polyethylene oxide (PEO) and polyacrylic acid (PAA), formed at low pH and held together by hydrogen bonding; and 3) two weak polyelectrolytes, polyallylamine hydrochloride (PAH) and polyacrylic acid (PAA). The PEMs formed from PDADMAC/PSS and PEO/PAA were studied using Stagnation Point Adsorption Reflectometry (SPAR), with SiO2 as the substrate. This was done to establish the formation of PEMs and, using PDADMAC/PSS, also to predict the influence of salt concentration during PEM formation. The amount of PDADMAC/PSS adsorbed was found to increase with salt concentration up to approximately 0.1 M NaCl. The formation of PEMs from PAH/PAA has already been studied in terms of structure; amount adsorbed, and influence on paper strength.
Sheets were formed from fibres treated with either PDADMAC/PSS or PEO/PAA PEMs and tested to determine paper tensile strength. Both PEM systems increased the tensile index and strain at break in the range of 100% when approximately 10 layers had been adsorbed. After several PEM layers had been adsorbed, the sheets made of fibres treated with PDADMAC/PSS differed in tensile strength depending on the polymer adsorbed in the outermost layer. A higher tensile strength was detected when PDADMAC rather than PSS was adsorbed in the outermost layer. Sheets made of fibres treated with PEO/PAA displayed a linear increase in strength, independent of which polymer that was adsorbed in the outermost layer.
The amount of adsorbed PDADMAC/PSS, as analysed using nitrogen and sulphur analysis, respectively, increased linearly, but with a higher amount adsorbed in the first layer. A comparison of the adsorption onto the SiO2-surfaces (SPAR-measurements) and fibres shows some differences. This is apparent both regarding the adsorption in the first layer and in the change in adsorbed amount with salt concentration. Despite this, one can conclude that SiO2 and wood fibres show very similar trends, and that SiO2 can be used as a convenient model surface in predicting PEM formation on wood fibres.
Individual fibres were also partially treated using a Dynamic Contact Angle Analyser, and the treated and untreated parts were analysed in terms of wettability and surface structure. The differences in wettability are significant, depending on the polymer system used and, with PAH/PAA PEMs, the pH strategy show a large influence in wettability. PDADMAC/PSS and PAH/PAA PEMs both had a large influence on wettability, depending on the polymer adsorbed in the outermost layer, wettability being lower when the cationic polymer was adsorbed in the outermost layer. With the PEO/PAA system, however, the polymer adsorbed in the outermost layer caused no detectable difference. These results, when compared against the paper strength results, indicate that the strongest sheets are formed of the fibres with the lowest wettability. This may be explained in terms of wet adhesion: since the fibre networks are formed in water, lower wettability would give a stronger force between the fibres during consolidation, resulting in a greater contact area and thus probably a stronger dry adhesion between the fibres in the formed sheet. This is furthermore also supported by wet adhesion measurements using Atomic Force Microscopy where PEMs formed from PAH/PAA, show that the pull-off force is increased when PAH is adsorbed in the outermost layer, compared to when PAA is adsorbed in the outermost layer.
Denna licentiatavhandling behandlar adsorption av polyelektrolytmultiskikt (multiskikt) på cellulosafibrer som ett nytt sätt att påverka en fibers ytegenskaper. Grundläggande förutsättningar för bildandet av multiskikt på fibrer diskuteras i termer av pappersstyrka och fibervätning.
Multiskikt har bildats med hjälp av tre olika polymerkombinationer; 1.) två starka polyelektrolyter, polydiallyldimetylammoniumklorid (PDADMAC) och polystyrensulfanat (PSS), 2.) polyetylenoxid (PEO) och polyakrylsyra (PAA), adsorberade vid lågt pH och sammanhållna av icke elektrostatiska vätebindningar, och 3.) två svaga polyelektrolyter, polyallylaminhydroklorid (PAH) och PAA. Uppbyggnaden av multiskikt bestående av PDADMAC/PSS och PEO/PAA på kiseloxid studerades med Stagnationspunktsreflektometri (SPAR) för att undersöka att uppbyggnad av PEM skett, samt att studera hur uppbyggnaden påverkas av koncentrationen NaCl i polymerlösningen. Försöken visade att den adsorberade mängden PDADMAC/PSS ökade med saltkoncentrationen upp till 0,05-0,1 M NaCl. Uppbyggnaden av multiskikt bestående av PAH/PAA är sedan tidigare studerad undersöks därför inte specifikt i detta arbete.
Laboratorieark tillverkades av fibrer som behandlats med multiskikt bestående av PDADMAC/PSS, respektive PAH/PAA. Fysikalisk pappersprovning av arken visade för båda systemen en ökning med cirka 100 % i dragindex för ark som tillverkats av fibrer som behandlats med cirka tio lager, jämfört med ark som tillverkats av icke-behandlade fibrer. Ark tillverkade från PDADMAC/PSS-behandlade fibrer visade att när 5-7 lager adsorberats, ett högre dragindex då PDADMAC adsorberats i det yttersta lagret, jämfört med då PSS adsorberats i det yttersta lagret. Ark tillverkade från fibrer behandlade med PEO/PAA visade ingen skillnad i dragindex beroende av vilken polymer som adsorberats i det yttersta lagret.
Den adsorberade mängden PDADMAC/PSS på fibrerna bestämdes med hjälp av kväve- respektive svavelanalys. Den adsorberade mängden polymer ökad linjärt som en funktion av antalet adsorberade lager, men med en högre adsorberad mängd i det första lagret. Dessa resultat har jämförts med den adsorberade mängden för multiskikt uppbyggda med SPAR på kiseloxid. Jämförelsen visade att det finns skillnader i uppbyggnaden mellan skikt byggda på kiseloxid och fibrer, men att kiseloxid med god tillförlitlighet kan användas som modellyta för att förutsäga generella trender för adsorptionen av samma polymersystem på cellulosafibrer.
Multiskikt har också bildats på enskilda fibrer med hjälp av en dynamisk kontaktvinkelmätare (DCA). Genom att behandla en del av en fiber, och jämföra den behandlade delen med den obehandlade delen på samma, kan ett multiskikts inverkan på fiberns ytstruktur och vätningsegenskaper studeras. De olika polymersystemen visade en avsevärd skillnad i förmågan att påverka en fibers vätningsegenskaper. För fibrer behandlade med PAH/PAA är också pH av stor betydelse för graden inverkan på fiberns vätningsegenskaper. Fibrer behandlade med PDADMAC/PSS och PAH/PAA, visade en sämre vätningsförmåga då den katjoniska polymeren adsorberats i det yttersta lagret, och vice versa. För enskilda fibrer behandlade med PEO/PAA, kunde inte konstateras någon skillnad beroende av vilken polymer som adsorberats i det yttersta lagret.
Vid en jämförelse mellan vätningsförmåga och pappersstyrka kan konstateras att de ark som visade den högsta styrkan tillverkats av fibrer där den lägsta vätningsförmågan har kunnat konstateras. Denna skillnad kan diskuteras med utgångspunkten i att en lägre vätningsförmåga resulterar i en högre våt adhesion och därmed en starkare interaktion mellan de polymerbehandlade ytorna i vått tillstånd. Det föreslås i avhandlingen att den ökade kraft som detta resulterar i vid bildandet av en fiber-fiberfog ger upphov till en högre kontaktarea och därmed, förmodligen, också en högre torr adhesion. Kraftmätningar i vått tillstånd för behandlade kiselmodellytor med hjälp av atomkraftsmikroskopi (AFM) har för PAH/PAA visat att den våta adhesionen är högre då PAH är adsorberats i det yttersta lagret, jämfört med då PAA adsorberats i det yttersta lagret. Detta stödjer hypotesen att en lägre vätning gynnar uppkomsten av en stark fiber-fiberfog.
47
Ramesh, Ram S. "Identification of Multi-Dimensional Elastic and Dissipation Properties of Elastomeric Vibration Isolators". The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1515109658022859.
Texto completo
48
Fathi, Leila Verfasser] y Arno [Akademischer Betreuer] [Frühwald. "Structural and mechanical properties of the wood from coconut palms, oil palms and date palms / Leila Fathi. Betreuer: Arno Frühwald". Hamburg : Staats- und Universitätsbibliothek Hamburg, 2014. http://d-nb.info/105504065X/34.
Texto completo
49
Fathi, Leila [Verfasser] y Arno [Akademischer Betreuer] Frühwald. "Structural and mechanical properties of the wood from coconut palms, oil palms and date palms / Leila Fathi. Betreuer: Arno Frühwald". Hamburg : Staats- und Universitätsbibliothek Hamburg, 2014. http://d-nb.info/105504065X/34.
Texto completo
50
Gu, Ruijun. "Mechanical properties and microstructures formations of wood thermoplastic composites = Propriétés mécaniques et formations des microstructures dans les composites bois-thermoplastiques". Thèse, Université du Québec à Trois-Rivières, 2010. http://depot-e.uqtr.ca/1798/1/030153867.pdf.
Texto completo