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Published: 30 May 2022
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1

Щукіна, Людмила Павлівна, Георгій Вікторович Лісачук, Ярослав Олегович Галушка, Олена Юріївна Федоренко, and Лариса Олександрівна Міхеєнко. "Технологічна цінність промислових хімічних добавок при їх використанні у виробництві будівельної кераміки." Thesis, Одеський національний політехнічний університет, 2013. http://repository.kpi.kharkov.ua/handle/KhPI-Press/31485.

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Досліджено технологічну ефективність комплексної поверхнево-активної добавки "MasterКерам" при її використанні у виробництві стінової кераміки для покращення властивостей керамічних мас і матеріалів. Встановлено водоредуційний ефект добавки та її позитивний вплив на міцність коагуляційної та конденсаційної структури мас. Визначена оптимальна кількість добавки, рекомендована для використання у виробництві стінової кераміки рядового призначення.
The technological efficiency of complex surface-active additive "MasterCeram" using to improve the properties of ceramic masses and materials in the manufacture of wall ceramics is investigated. The water-reducing effect of the additive and its positive influence on the strength of the coagulation and condensation structure of ceramic masses are established. The optimal amount of additive, which recommended for use in the manufacture of terraced wall ceramic, are established.
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2

Yang, Nana. "Structural strength and reliability analysis of composite structures." Thesis, University of Strathclyde, 2010. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=13242.

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3

Cofer, William Franklin. "An analytical determination of ultimate strength of tubular joints for offshore structures." Diss., Georgia Institute of Technology, 1988. http://hdl.handle.net/1853/21494.

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4

Rouaiguia, Ammar. "Strength of soil-structure interfaces." Thesis, Loughborough University, 1990. https://dspace.lboro.ac.uk/2134/26883.

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This research work deals with the development of the shearbox apparatus by introducing a micro-computer to automatically collect all the results, and to apply normal and shear stresses. A continuous statement of time, channel number, and transducer input and output is produced for each test, the sequences of applied rates of displacement and normal stresses for which were programmed.
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5

Prandato, Emeline. "Relations structure-propriétés et résistance à l’endommagement de vernis acrylate photo-polymérisables pour substrats thermoplastiques : évaluation de monomères bio-sourcés et de nano-charges." Thesis, Lyon, INSA, 2013. http://www.theses.fr/2013ISAL0103/document.

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L’objectif de ces travaux a été de développer des vernis acrylate photo-polymérisables à 100% d’extrait sec, destinés à protéger des pièces thermoplastiques en polycarbonate contre les endommagements mécaniques, en particulier contre la rayure. Les relations entre la composition, la structure et les propriétés de ces revêtements ont été explorées. Pour ce faire ont été étudiées la morphologie, les propriétés thermomécaniques ainsi que la résistance à la rayure des matériaux. Cette dernière a été évaluée par des tests de micro-scratch. La cinétique de formation des réseaux polymères a elle aussi été étudiée, par photo-DSC. Tous les matériaux étudiés présentent, en analyse thermomécanique dynamique, un module élevé à l’état caoutchoutique ainsi qu’une large relaxation mécanique. Un vernis pétro-sourcé à 100% d’extrait sec, qualifié de standard, a servi de point de départ à ces travaux. Il a tout d’abord été comparé à un vernis commercial solvanté photo-polymérisable, spécialement conçu pour la protection de pièces thermoplastiques. Celui-ci s’est avéré être plus efficace en termes de résistance à la rayure. Dans un deuxième temps, a été étudiée l’influence sur les propriétés du vernis standard pétro-sourcé d’un monomère multicyclique entrant dans sa composition. La modification de son pourcentage n’a permis d’apporter aucun bénéfice en termes de résistance à la rayure. Des nanoparticules de silice, d’alumine ou de zircone, disponibles sous forme de dispersion dans un monomère acrylate, ont ensuite été incorporées dans le vernis standard pétro-sourcé. Une organisation particulière de la nano-silice et de la nano-alumine au sein des matériaux étudiés a pu être observée par microscopie électronique en transmission. Il a été constaté que le taux de charge doit être élevé pour observer une augmentation du module élastique et une amélioration de la résistance à la rayure du vernis (≥15% massique dans le cas de la nano-silice). Par ailleurs, l’ajout de 5% massique de nano-silice dans le vernis n’a conduit à aucune modification de sa cinétique de photo-polymérisation. Enfin, une partie des composés acrylate pétro-sourcés du vernis standard a été substituée par des acrylates bio-sourcés disponibles industriellement. La cinétique de photo-polymérisation des deux types de vernis est similaire. Les conclusions de la comparaison entre les vernis bio-sourcés et le vernis standard pétro-sourcé en termes de résistance à la rayure dépendent de l’épaisseur des revêtements étudiés. L’ajout d’un composé monoacrylate bio-sourcé à la formulation des vernis tend à améliorer la recouvrance élastique des revêtements de faible épaisseur. L’acrylate d’isobornyle est en particulier intéressant, car il a aussi tendance à retarder l’apparition des craquelures au cours de la rayure
The aim of this work was to develop 100% solids photo-polymerizable acrylate coatings, intended to protect thermoplastic pieces made of polycarbonate against mechanical damage, in particular scratches. The relationships between the composition, the structure and the properties of these coatings were examined. For this purpose the morphology, the thermomechanical properties and the scratch resistance of the materials, assessed by micro-scratch tests, were studied. The kinetics of the polymer network formation was also studied by photo-DSC experiments. All the materials feature a high elastic modulus and a broad mechanical relaxation in dynamic thermomechanical analysis. A 100% solids petro-based coating (standard) constituted the starting point of this work. First it was compared to a commercial photo-polymerizable coating containing solvents, specially designed to protect thermoplastic pieces. This commercial coating turned out to be more efficient against scratches. In a second time was studied the influence of the percentage of a multicyclic monomer, taking part in the composition of the standard petro-based coating, on the properties of the latter. The modification of its proportion does not bring any advantage concerning the scratch resistance. Silica, alumina and zirconia nanoparticles, dispersed in an acrylate monomer, were then incorporated in the standard petro-based coating. A particular organization of the silica or alumina nanoparticles in the materials could be observed by transmission electron microscopy. A high filler content is required to observe an increase in the elastic modulus and an enhancement of the scratch resistance of the coating (≥15% by weight for the nano-silica). Moreover, no change of the photo-polymerization kinetics was noticed through the addition of 5% by weight of nano-silica in the coating. Finally, some of the petro-based acrylate compounds of the standard coating were substituted by commercially available bio-based acrylate monomers. Both types of coatings feature similar polymerization kinetics. The conclusions concerning the comparison of the scratch resistance of the bio-based and standard petro-based coatings depend on their thickness. The incorporation of a bio-based monoacrylate compound in low thickness coatings tends to improve the elastic recovery. Isobornyl acrylate is particularly interesting since it also tends to delay the apparition of cracks along the scratch
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6

Moe, Heidi. "Strength analysis of net structures." Doctoral thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for konstruksjonsteknikk, 2009. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-5411.

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The main goal of this PhD project was to develop a method for non-linear strength analysis of net structures applied in the aquaculture and fishing industries, e.g. net cages and trawls. The work focused on the aquaculture net cage, which was applied in experiments and analyses, and included research to establish knowledge within material properties and failure modes of traditional netting materials for aquaculture. It was chosen to focus on tensile properties and to study elastic and plastic behaviour, fracture, creep behaviour and cod bite damage. The project consisted of three main activities: tensile testing of netting materials, studies and testing of cod bite damage and resistance, and structural analysis of aquaculture net cages. Net cages are built as a system of ropes and netting. They are designed to transfer and carry all major forces through the ropes. Loads from current, waves, weights and handling induce forces in the net cage, which must be dimensioned to withstand this. Analyzing an aquaculture net cage is both complex and time consuming due to non-linear effects, detailed geometry and dynamic loads. The behaviour of the net cage is dominated by very large deformations and displacements, and materials with non-linear properties. There is a need for verified analysis methods and specific guidance on how to reduce the complexity of a net cage analysis. In order to perform a strength analysis of a net cage, it is crucial to know the material properties of the netting material. Traditionally, the material property of major interest for the aquaculture industry has been the tensile breaking strength of netting (mesh) and ropes, and comparatively little focus has been on their detailed stiffness properties and general behaviour prior to fracture. A new test method was established to determine the uniaxial tensile properties of knotless netting materials. It was applied on a variety of netting materials and stress-strain relations were developed. Data on temporary creep properties, recovery of strain post creep and post creep tensile properties of a selection of Raschel knitted netting materials was presented. Post creep tensile testing showed that the length and force at break were not significantly affected by the creep load history. Cod farmers have reported that cod interact with the cage netting through biting and thereby create wear and tear. The nature of the cod bite attack on traditional, multifilament netting materials was described based on studies of cod interaction with traditional knotless netting and resulting fracture damage on netting fibres. Field experiments were performed, subjecting panels of netting to cod bite in commercial cod cages. In addition, a test method was developed to simulate damage on traditional netting from cod bite, and a prototype bite-jig was designed and assembled. It was concluded that netting materials for cod aquaculture must be resistant to cod bite or be repellent or uninteresting for cod. A method for numerical analysis of net cages in constant uniform current was developed and verified for limited solidity, deformations and current velocities. Various new designs for aquaculture net cages were presented and compared to a traditional net cage with regard to stresses in the netting material and deformation of the net cage.
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7

Hou, An. "Strength of composite lattice structures." Diss., Georgia Institute of Technology, 1997. http://hdl.handle.net/1853/12475.

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8

Moreland, Angela. "The structure and strength of metallurgical coke." Thesis, Loughborough University, 1990. https://dspace.lboro.ac.uk/2134/13759.

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This study aimed to investigate the relationship between the tensile strength of metallurgical coke and both the textural composition of the carbon matrix and the porous structure of the coke, and further to assess the use of these structural features as bases of methods of coke strength prediction. The forty-four cokes examined were produced in a small pilot-oven from blended-coal charges based on six coals differing widely in rank. Their textural composition was assessed by incident polarized-light microscopy while pore structural parameters were measured by computerized image analysis allied to reflected light microscopy. The tensile strength of coke could be related to textural data with accuracy using several relationships, some of which were based on a model for the tensile failure of coke. Relationships between tensile strength and pore sturctural parameters were less successful, possibly because of difficulties associated with the measuring system used. Neverthless relationships involving combinations of pore structural and textural data were developed and investigated. It was shown that relationships between tensile strength and calculated textural data had promise as the basis of a method of coke strength prediction. Also, tensile strengths could be calculated from the blend composition and the tensile strength of the coke produced from component cokes. Both methods have value in different situations.
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9

Abbasi, Erfan. "Processing and structure of high strength steels." Thesis, University of Sheffield, 2015. http://etheses.whiterose.ac.uk/9466/.

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There is currently an extensive effort to develop new steels with a better combination of strength and ductility, the so-called Ultra-High Strength Steels (UHSS) and Advanced High Strength Steels (AHSS). The new steels must be able to be manufactured using existing plant and at the same time meet ever decreasing cost demands. This study looks at developing AHSS, with a focus primarily on the microalloying precipitation behaviour and microstructural evolution during thermomechanical processing of transformation induced plasticity (TRIP) assisted steels. This approach combines two mechanisms that are known to enhance properties, namely the TRIP effect and precipitation hardening arising from strain induced precipitation. In respect of the TRIP effect, a detailed investigation was undertaken to look at the effect of the intercritical anneal on strength and ductility. For the strain induced precipitation, the effect of combined microalloy additions was investigated. Initially, the effect of intercritical annealing was studied using a trial as-cold rolled multiphase V microalloyed TRIP assisted steel with a polygonal ferrite matrix (1.5Mn C+Si+Al+N≈1.0 (C 0.2) and V˂0.2 wt%) focusing on the isothermal bainite transformation at 460°C. The V(C,N) precipitates were extensively observed in all phases (ferrite, retained austenite, martensite and bainitic ferrite) after isothermal bainite transformation in a random manner. The tensile testing suggested considerable improvements in yield, ultimate tensile strengths and elongation after 180s isothermal bainite holding time. According to SEM/TEM observations, these effects were attributed to the evolution of retained austenite from block to film morphology, and possible interaction between microalloying precipitates and newly formed dislocations as a result of bainite transformation. The average density of V(C,N) slightly increased after intercritical annealing, though it did not show a significant variation during the isothermal bainite transformation. Nevertheless, the size distribution of V(C,N) precipitates did not change significantly. The effect of a combined addition of Nb, Mo and V was investigated in TRIP multiphase steel (0.12C 1.50Mn 1.50Si and NbVTiMo≤0.20 wt%), which was compared to a V single addition steel with otherwise matched composition. A comparative study was undertaken using intercritical annealing after ~20% cold-rolled deformation of the rough rolled specimens. The resulting microstructure in both alloys comprised acicular/bainitic ferrite with an uneven proportion of allotriomorphic ferrite and retained austenite and martensite. An average density of precipitates increased in both alloys after intercritical annealing, with an average of 137 and 219 precipitate/µm2 in NbVMo and V steels, respectively. NbV(C,N), NbVMo(C,N) and V(C,N) were observed in the NbVMo steel. In both alloys, precipitates with different morphologies were observed, located in the matrix, on dislocations and at grain boundaries. The results suggested that the NbMo addition retarded the growth/coarsening of precipitates with a size of lower than 15nm. Also, much greater precipitation strengthening was observed in the NbVMo steel after intercrital annealing compared to the V steel. The last part of the project was to systematically study the effect of Nb and Mo on the V steel as a function of thermomechanical processing. Laboratory simulations were developed by plane strain compression testing which accurately replicate the whole thermomechanical process route from the hot rolling through intercritical annealing, followed by the bainite transformation. After hot and controlled rolling at intercritical annealing range the resulting microstructure was acicular/bainitic ferrite, retained austenite and martensite surrounded by allotriomorphic ferrite in both alloys. The TEM observations suggested that a noticeable number of precipitates were formed in the NbVMo steel up to the finishing stage (i.e. average of 112 precipitate/µm2 in NbVMo containing steels). It was also found that the V(C,N) precipitation occurred in austenite and ferrite below the finishing stage (i.e. ≤830˚C) with an average cooling rate of ~12˚C/s. The overall findings suggest that the high dislocation density in the ~20% cold rolled acicular/bainitic ferrite could lead to an intense precipitation and coarsening of V(C,N) during the intercritical annealing.
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Robertson, I. "Strength loss in welded aluminium structures." Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372908.

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11

Halabi, Walid Charif. "High Strength concrete corbels." Thesis, University of Aberdeen, 1991. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU047734.

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Concrete is still the most widely used construction material of modern times. In very recent years attempts have been made by using steel fibre reinforcement to improve the inherent weaknesses that concrete possesses such as its low tensile strength and the tendency to shrink on drying and to creep under stress. In this context, the use of steel fibre reinforcement together with high strength concrete corbel joints has been investigated. This study came after fibre reinforced concrete had received wide recognition for its crack and deformation control, ductility and energy absorption characteristics. In the present study, the fracture behaviour and deformation characteristics of plain conventionally reinforced concrete corbels with and without steel fibre reinforcement has been investigated. The different types of steel fibres used and other experimental materials are described in chapter 3, whereas chapter 2 gives a review of the old and current design approaches used for concrete corbel design. In chapter 4 the deformation, cracking and ultimate strength of plain high strength concrete corbels has been studied with different cube strength ranged between 25 to 90 N/mm2. In chapter 5 a proposed theory to predict the ultimate strength of high and normal strength concrete corbels, conventionally reinforced, has been derived. The influence of steel fibre reinforcement on the performance of conventionally reinforced concrete corbels has been studied in chapter 6. Melt extract steel fibres were used in the majority of the corbels together with other types such as crimped, hooked and plastic fibres (polypropylene). In the same chapter 6, the theory has been extended to account for the strength gained by fibre addition. The effect of steel fibre reinforcement on the shear transfer strength has been studied in chapter 7. The theory proposed in chapter 5 has been further extended to predict the shear strength of 'push-off' type of specimens of plain and fibre reinforced concrete, with conventional steel reinforcement.
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12

Nezamian, Abolghasem 1968. "Bond strength of concrete plugs embedded in tubular steel piles." Monash University, Dept. of Civil Engineering, 2003. http://arrow.monash.edu.au/hdl/1959.1/5601.

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13

Underwood, J. "Strength assessment of damaged steel ship structures." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/355704/.

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In 2012 106 vessels over 100 gross tonnes were lost. During the damage incidents many of these vessels required assistance from shore based emergency response services with regards to their damaged strength to stabilise the situation, preserve life, prevent environmental disaster and limit financial costs to owners and insurers. The research work presented in this Engineering Doctorate Thesis surrounds the strength assessment of damaged steel ship structures, the influence of damage on the strength of steel-plated structures and methods for assessing the residual strength of a vessel in an emergency. The focus of the work is to improve the modelling of damaged steel ship structures within an emergency situation, in order to improve guidance provided to a stricken vessel during a damage incident or salvage process. Literature study has shown that structural idealisation through the use of interframe progressive collapse analysis, to be the current state of the art method for the rapid assessment of intact and damaged ship structures. However, a number of weaknesses have been identified in the method when applied to damage assessment. The literature study has also shown a lack of understanding of the effect of damage on steel-plated structures as specific analysis has not been performed previously. Significant research has been undertaken into the influence of damage, in the form of a hole, on the ultimate collapse strength of steel-plated structures. Three levels of structural modelling have been used, stiffened-plate, stiffened panel and grillage. Comparison of the predicted ultimate collapse strength by finite element analysis (FEA) with predictions using the interframe progressive collapse idealisation, has shown the calculated results to be conservative for the assessment of damaged structure when the failure mode remains in the interframe collapse form. However, changes in the failure mode lead to the interframe progressive collapse method over predicting the ultimate collapse strength. The analysis shows that even small damage events can lead to significant changes to the failure mode and resulting ultimate collapse strength of the structure. Such influences must be accounted for in any simplified method. A new method for the assessment of damaged ship structures is proposed that is capable of modelling a damage scenario more accurately. Demonstration of the method has shown the results to be less conservative than the current state of the art, when compared to FEA, for local analysis of damaged steel-plated structure. The ability of the method to account for the influence of damage, and the resulting failure modes, that may significantly influence the ultimate bending strength of the structure has also been demonstrated. The method implements a compartment level progressive collapse analysis with structural data captured through the use of the response surface method ‘kriging’, using data points provided from FEA. This method allows the critical damage variables to be captured and strength data accessible quickly for use in the analysis. The time to provide a solution to the damage scenario is equivalent to the existing interframe progressive collapse method. Therefore, the method is suitable for application within an emergency response or salvage service.
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14

Amador, Lui. "Strength within| Addressing Structural Opportunity Gaps for Men of Color at 4-Year Universities through a Strengths-Based Approach." Thesis, California State University, Long Beach, 2018. http://pqdtopen.proquest.com/#viewpdf?dispub=10825323.

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The enrollment, retention, and graduation rates for African American, Latino, Native American, and segments of Asian and Pacific Islander men in higher education are disproportionately lower than women from all racial groups and White men. A significant body of research substantiates the concern by institutions on the opportunity gap for men of color in higher education. Despite the research and concerted efforts by institutions, this opportunity gap continues to affect the educational and overall college experience of men of color. Through qualitative interviews employing a photo elicitation protocol and a conceptual framework based on validation theory, Critical Race Theory (CRT) and Anti-Deficit Perspectives, this study examines the social, cultural, and institutional factors that shape this population’s experience in higher education. This research will examine the strengths and assets that men of color identify as supporting their success in college. This study will also examine how institutional resources and practices informed by an anti-deficit framework can effectively improve the experiences of men of color in school.

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15

Sinclair, John. "Crusting, soil strength and seedling emergence in Botswana." Thesis, University of Aberdeen, 1985. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU363198.

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This thesis gives the results of an investigation of the strengths and particularly the crust forming potential of arable soils from Botswana and the relationship to seedling emergence of sorghum, the most important crop in Botswana and one that because of its small seed weight (about 2 0 mg) can fail to emerge through a hard soil crust. A review of the literature suggested that the soil factors which had to be considered were dispersibility of clay and factors which affect this, and the bulk density of the soils. Soils which are found in many tropical and sub-tropical regions, with low organic matter and inactive clays can set hard after a simple wetting and drying cycle. In these soils, the strength is very strongly dependent on the water content, showing a hyperbolic or exponential relationship-, and the strengths when dry may be very greatly increased by remoulding the wet soil. The crust strength required to prevent seedling emergence varies with the size of the seedling and for cotton (seed weight about 80 mg), 1-3 MPa penetration resistance measured with a penetrometer is sufficient to prevent emergence. Seedlings exert a total force proportional to their number. In the experimental programme, seedlings' forces were measured, seedling emergence observed in a field experiment under crusting conditions, and the strength characteristics of a group of soils, representative of arable soils in Botswana, studied. A sorghum seedling was found to exert a maximum force of about 1 N or dividing by the area of the plumule, a pressure of about 0,5 MPa. The field experiment showed that much better emergence was obtained from planting 15 seeds together than from planting 4 seeds together when a crust formed after planting. A study of 32 soils, most of them sand to sandy loam in texture but with a few clays and hydroirorphic soils, from arable areas in Botswana showed the sandy to sandy loam soils to have high bulk densities ( 1,45-1 ,75 Mg/m3) and extremely low organic carbon contents (0,12-0,85 g/100g). The bulk densities of all the soils were inversely related to the organic carbon content and this was itself related to the clay content of the soils. The bulk densities of the sands were dependent on the grading of the sand fraction. Many of the soils were sensitive to remoulding in the Emerson test and the sands to loany sands had 0,4-1,0 g/100 g water dispersible clay. Measurements of tensile strength on air-dry samples showed that all the soils, except for one sand, set hard after a wetting and drying cycle, giving for vacuum wet samples indirect tensile strengths 1,0-14,4 kPa. For the sands to sandy loams this strength was related to the water dispersible clay content. Samples wet at atmospheric pressure were weaker than the vacuum wet samples, the reduction in strength was related to the air porosity of the non-vacuum wet soils prior to drying. Remoulding the soils prior to drying them increased the strength by a factor of up to 50 times, giving strengths from 4 kPa to 600 kPa. The strength after remoulding was dependent on the Emerson index. Compacting the soils increased their strength greatly and to an extent that agreed with the hypothesis that the strength obtained was proportional to the area of contact between the particles. Experiments on penetration resistance at a range of water contents were performed on a few soils. A hyperbolic relationship between water content and penetration resistance of the surface soil was found for sand to sandy loam soils, with the maximum resistance of dry soils above 2 MPa. The penetration resistance of the sandy loam soil was Increased three times by disturbing it when wet. Sprinkler wetting the sieved soils was not found to affect the penetration resistance by a large amount compared and other methods of welting. Penetration resistance was measured on air-dry samples of most of the main group of soils following varying degrees of wetting with a rainfall simulator. The clays and hydromorphic soils gave very low values of penetration resistance under these conditions, showing that at organic carbon contents of about 1% and clay contents from 20 to 30%, the decreased bulk density and tendency to form aggregates' on drying overcame the tendency to set hard. The mean values for the sands to sandy loams were from 1 to 6 MPa so all these soils could offer significant resistance to a sorghum seedling. The penetration resistance of the sands and loam/ sands depended on their bulk densities and water dispersible clay contents, while the penetration resistance of the sandy loams depended only on the water dispersible clay content.
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16

Haghi, Arsalan Khodaparast. "Shear strength characteristics of bog peat." Thesis, University of Salford, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305924.

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17

Balart, Murria Maria Jose. "Structure-property relationships in high strength microalloyed forging steels." Thesis, University of Birmingham, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.364519.

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18

Choudhury, Ajmol H. "Structure, strength and defect characterisation of cement based materials." Thesis, Robert Gordon University, 2014. http://hdl.handle.net/10059/1031.

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In cement based systems, the residual stresses are created by internal expansion. This provides toughening by the release of the residual stresses as the macro-crack propagates. While circumstantial evidence of the residual stresses exist (e.g. micro-crack formation leading to permanent deformation in flexural tests), it is very difficult to observe the mechanism in action. The quantitative estimate of the changes occurring in such cement-based systems is challenging due to the anisotropy and complexity of the material. Non-Destructive Testing (NDT) techniques were used in this research to observe the mechanism in action. An ultrasound technique is used to examine strength development and an acoustic emission (AE) technique is used to examine micro-structural changes, micro-cracks, crack initiation, crack propagation, crack arrests and crack bridging in plain concrete samples including samples containing admixtures and waste materials. The NDT techniques were found to be accurate in being able to measure compressive strength, with good correlation between both standard mechanical testing and NDT techniques. It was shown that admixtures could be effectively used to alter the properties of a curing cement mortar. This work has also demonstrated that ultrasound can be successfully used to determine the compressive strength of concrete from an early age. The ability to pre-determine the strength of concrete through correlation with NDT test parameters may reduce the time spent waiting on concrete to set and to obtain results using standard mechanical testing methods. The findings in this research present the effect admixtures had on the curing process of the cement based material. The introduction of certain additives into mortars have demonstrated an increase in both the rate of initial hardening and the magnitude of the compressive strength attained over the curing period depending on the mixture specification. The additives considered have been shown to actively alter and enhance the chemical process of curing from the start of hydration. Some additives that accelerate the curing process (accelerators) were found to lower the compressive strength of concrete using the ultrasound technique. Additives that caused an increase in the final strength of mortar also increased its toughness. The significant contributions in this research enabled observation of micro-structural changes and failure behaviour under compressive and flexural loading conditions on an on-line basis. The results obtained are encouraging and lead to increased understanding of cracking mechanisms in concrete containing various types of additives and aggregates. The application of the AE technique allowed the failure of interfacial bonding to be observed. The variation of the aggregate size and its effect on the monitored waveforms was established and the parameters in the AE signals are directly related to crack propagation (grain bridging/micro-mechanism) and strength of interfacial bonding. These findings have greatly contributed to the understanding of the concrete behaviour under complex conditions where no other technique could provide such valuable information on an online basis.
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19

Ouakka, Slimane. "On the static strength of reinforced joints." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.

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The title, On the Static Strength of Reinforced Joints, shows the main subject of this research. The main aim of this study is to analyze the static strength of joints when geometrical and/or mechanical parameters change, by the use of Finite Element (FE) Model. In the current study a FE Model with the use of shell element was modelled as requested from the codes, that for a new configuration of Joints suggest using FE Models, and since this type of strategy are mesh dependent especially for cases where the concentration of stress is sharp it needs to be calibrated by using physical experiments. Even if a three-dimensional is already present in the literature, through the shell model that requires much less computational effort, a great result was achieved. The results of this research and the references reveal a very good correlation in terms of load-ovalization curves and also in terms of deformed shape. Reflecting not only the shapes of curve and deformation but also even more relevant the different values of enhancement of the strength when the parameters varying as obtained in the Experimental Investigation. The research is subdivided in four chapter, starting from the first chapter where the importance of this type of element is highlighted and the advantage in using this type of elements in the structures such as jackets of offshore platforms. This first followed by the explanation of the key points of the two previous reference. Then in the third chapter, the finite element strategy was explained and the results are shown. Finally, in the fourth chapter given the results of the previous chapters, some conclusions and considerations can be made. In conclusion, this results can be used as a base of other typology of elementary joints as Y-joint, K-joint and X-joint, or a combination elementary joints.
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Kultikova, Elena V. "Structure and Properties Relationships of Densified Wood." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/35810.

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The objective of this research was to investigate the effect of applied compressive strain in various environments, on the strength and stiffness of compressed wood samples. It is believed that transverse compression of wood at specific conditions of temperature and moisture will result in improved mechanical properties, which can be attributed to increased density and perhaps other physical or chemical changes.

Specimens of both mature and juvenile southern pine (Pinus taeda) and yellow-poplar (Liriodendron tulipifera) were compressed radially at three different temperature, and moisture content conditions relevant to the glass transition of wood.

Ultimate tensile stress and longitudinal modulus of elasticity were obtained by testing compressed, uncompressed and control samples in tension parallel-to-grain. Strain measurements were performed using laboratory-built clip-on strain gauge transducers. Results of the tensile tests have shown an increase in the ultimate tensile stress and modulus of elasticity after all densification treatments.

Scanning electron microscopy was employed for observing changes in cellular structure of densified wood. Existence of the cell wall fractures was evaluated using image processing and analysis software. Changes in cellular structure were correlated with the results of the tensile test.

Chemical composition of wood samples before and after desorption experiments was determined by acid hydrolysis followed by high performance liquid chromatography (HPLC). The results of the chemical analysis of the wood specimens did not reveal significant changes in chemical composition of wood when subjected to 160 °C, pure steam for up to 8 hours.

The results of this research will provide information about modifications that occur during wood compression and will result in better understanding of material behavior during the manufacture of wood-based composites. In the long run, modification of wood with inadequate mechanical properties can have a significant effect on the wood products industry. Low density and juvenile wood can be used in new high-performance wood-based composite materials instead of old-growth timber.
Master of Science

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Khurshid, Mansoor. "Static and fatigue analyses of welded steel structures : some aspects towards lightweight design." Doctoral thesis, KTH, Lättkonstruktioner, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-200829.

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The objectives of this thesis comprise of overcoming the challenges in designing lightweight welded structures such as material selection, choice of fatigue design methods, and increased performance by using improvement techniques. Material selection of welded joints is dependent on the filler and base material strengths. Partially and fully penetrated cruciform and butt welded joints were designed in under-matching, matching, and over-matching filler materials. Base material steel grades were S600MC, S700MC, and S960. Current design rules are developed for welds in steel up to yield strength of 700MPa. Therefore, design rules in Eurocode3, AWS d1.1, and BSK 07 were verified and recommendations for developing design rules for designing welded joints in S960 were concluded. Numerical methodology for estimating static strength of welded joints by simulating heat affected zone was also developed. Another objective of the thesis work was to overcome the challenges in selection of fatigue design methods. The available design curves in standards are developed for uniaxial stress states, however, in real life the welds in mechanical structures are subjected to complex multiaxial stress states. Furthermore; weld toe failures are frequently investigated, weld root failures are seldom investigated. Therefore, in this work the multiaxial fatigue strength of welded joints failing at the weld root was assessed using experiments and various nominal and local stress based approaches. Butt welded joints with different weld seam inclinations with respect to applied uniaxial loading were designed to assess the root fatigue strength in higher multiaxial stress ratio regime. The fatigue strength of multi-pass tube-to-plate welded joints subjected to internal pressure only and combined internal pressure and torsion in and 90° out of phase loading was also investigated. Test data generated in this thesis was evaluated together with the test data collected from literature. Last objective of the thesis included investigation of the increased performance in fatigue strength by post weld treatment methods such as HFMI. The behavior of residual stresses induced due to HFMI treatment during fatigue loading is studied. Numerical residual stress estimations and residual stress relaxation models are developed and the effect of various HFMI treatment process parameters and steel grade on the induced residual stress state is investigated. Specimens studied were non load carrying longitudinal attachments and simple plates. Residual stresses in both test specimens were measured using X-ray diffraction technique.

QC 20170206

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Carroll, Travis S. "Predicted residual strength of damaged IsoTruss® structures /." Diss., CLICK HERE for online access, 2006. http://contentdm.lib.byu.edu/ETD/image/etd1157.pdf.

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Nyman, Tonny. "Fatigue and residual strength of composite aircraft structures." Doctoral thesis, KTH, Aeronautical Engineering, 1999. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-2848.

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Alkhalil, M. F. S. "Strength of filament wound structures under complex stresses." Thesis, University of Manchester, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.387260.

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Carroll, Travis S. "Predicted Redidual Strength of Damaged IsoTruss® Structures." BYU ScholarsArchive, 2005. https://scholarsarchive.byu.edu/etd/347.

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This thesis utilized a linear analytical approach to explore the damage tolerance or residual strength as a function of increasing damage in traditional single and hybrid-grid IsoTruss® structures. Residual strength was studied for structures subjected to axial compression, torsion and flexural bending, independently. Carbon/epoxy material properties were applied in all load cases, and fiberglass/epoxy material properties were also applied in the flexural bending case. Prior to imposing damage conditions, the IsoTruss® structures were parametrically optimized to achieve the highest strength-to-weight ratios. Typical compression strut, driveshaft, and utility pole specifications governed the design strength dimensions and boundary conditions. Damage growth was achieved by removing members from IsoTruss® structures progressively about the circumference in a symmetrical manner. The sequence of member removal, beginning with primary or secondary members, was examined, and is described as primary and secondary analyses. ABAQUS finite element analysis was employed to quantify the residual strength of each IsoTruss® configuration. Reduction in residual strength trends are compared to net section strength, which assumes a linear relationship between damage size and residual strength. Results indicate that the 6-node IsoTruss® configuration is the most damage tolerant structure in the sense that the 6-node configuration deviates the least from the net section strength. As more nodes are added, IsoTruss® structures behave more like a composite tube, exhibiting a brittle behavior characterized by an increase in strength reduction for a given damage size. Bending results reveal that carbon fiber IsoTruss® structures are more damage tolerant under primary bending conditions than fiberglass poles. On the other hand, fiberglass IsoTruss® poles prove to be more damage tolerant under secondary bending conditions than carbon fiber structures. Most importantly, however, hybrid-grid IsoTruss® poles are definitively more optimal structures than single-grid poles in terms of both strength-to-weight ratio and damage tolerance. The results and conclusions from this thesis provide benchmark capacities for mechanically manufactured IsoTruss® structures. Also included in this thesis is documentation of a special program written to analyze IsoTruss® structures.
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Wang, Jie. "Behaviour and design of high strength steel structures." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/43758.

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High strength steels (HSS), which are generally considered to be those with yield strengths over 460 MPa, are being increasingly utilised in construction, particularly in high rise structural applications and where long and column-free spans are an important design requirement. In place of ordinary carbon steels, the use of HSS can enable structural elements with smaller cross-sections, resulting in significant material savings. However, compared to normal strength steels, the structural use of HSS is still quite rare. The European design code EN 1993-1-12 provides design rules for HSS up to S700, but was conceived as a simple extension of the rules in EN 1993-1-1 for normal strength steels. In order to contribute to the existing limited HSS data pool and to verify and develop the current Eurocode 3 design rules, a comprehensive experimental programme on hot-finished S460 and S690 square and rectangular hollow sections has been carried out. The testing programme covered different structural aspects at the material, cross-section and member levels and consisted of 40 tensile coupon tests, 11 compressive coupon tests, 11 stub column tests, 11 full section tensile tests, 22 in-plane bending tests, 12 eccentrically loaded stub column tests, 30 long column tests, as well as measurements of geometrical imperfections and residual stresses. Numerical models, validated against the test results, were also developed to examine the cross-section and member behaviour, and subsequently employed in a comprehensive parametric study in order to generate further data. Based on the combined test and numerical data set, as well as experimental results reported in the literature, the current HSS design rules in Eurocode 3, including the slenderness limits for cross-section classification, effective width equation, N-M interaction curves and column buckling curves, were assessed by means of reliability analyses in accordance with Annex D of EN 1990. To realise the potential of HSS in long span structures, a novel structural form was also examined, namely an HSS truss with prestressing cables housed within the tubular bottom chord. A total of 4 prestressed trusses, made of S460 square hollow sections with different prestress levels, were tested under static downward loading. The truss test results showed the enhanced structural efficiency brought about by the addition of prestressing cables and by the application of prestress. Additionally, 12 tensile and 10 compressive member tests with cables, representing the bottom chord of the truss under gravity and uplift loading, respectively, were carried out to investigate the behaviour of individual prestressed cable-in-tube members. Analytical models and numerical models were also established to compare with the test behaviour and to contribute to the development of design rules for prestressed cable-in-tube systems.
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Roumani, N. A. "The shear strength of prestressed brickwork sections." Thesis, University of Manchester, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374836.

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Gambo, Abdullah Hadejia. "Finite element prediction of masonry shear strength." Thesis, University of Sussex, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.315779.

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Xue, Hongyu. "Structural behaviour of high strength concrete columns." Thesis, University of Westminster, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.339246.

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Bang, Won B. "Improving the strength of 3DP parts and development of controlled strength cellular structure investment casting shell." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/38200.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1996.
Includes bibliographical references (p. 79).
Three Dimensional Printing (3DP) is a rapid prototyping process that creates a three dimensional part directly from computer models by printing a sequence of two dimensional layers. In this research, the strength of 3DP parts were improved by using different "print styles" (the way binder is deposited on the powder bed in creating a 3DP part) for use in investment casting process. The print styles that were created optimized line to line interaction between the printed lines, binder overlap, and the amount of unprinted powder surrounding the printed features. The strength of the parts are measured in three different axes (X-fast, Y-slow, Z). The strength improved by factors of 2, 8, and 7 for the three different axes. A controlled strength cellular structure investment casting shell that enables the creation of a metal part without any stress related defects has been created. The ceramic shell has an open cell frame structure with thin inner shell where the metal casting is poured. The flexibility of the 3DP technology applied to controlled strength cellular structure investment casting shell will incorporate all the advantages of 3DP to investment casting (Sach 1992, ASME) as well as reduction in material consumption, controlled heat transfer, permeability, and of course controlled strength to eliminate stress related defects. The cellular structure ceramic mold is designed to withstand the pouring pressures of the molten metal and survive the handling during processing yet fail when the stresses from the contracting metal becomes excessive. The 3DP molds are usually 60% porous and cellular structure investment casting shells consist of only 35% of the 3DP material per volume. A controlled strength cellular structure investment casting shell is designed to fail when excessive stress is applied to the shell structure. The stress on the casting shell is caused by the shrinkage of the metal part. The controlled strength investment casting shell has an open cellular structure frame with a thin inner shell where the metal casting will form.
by Won B. Bang.
S.M.
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31

Farrell, Robert William. "Structural Features Related to Tree Crotch Strength." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/32619.

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Crotches were cut out of red maple (Acer rubrum), callery pear (Pyrus calleryana), and sawtooth oak (Quercus acutissima) trees (2.5â -7â d.b.h.) and then pulled apart in an engineering testing machine to identify physical parameters correlated with crotch strength. Parameters measured included the diameter of the branch and of the trunk above and below the crotch, angle of the branch and branch bark ridge, and the length of the crotch and the branch bark ridge. The force required to break each sample was used to calculate breaking strength based on the formula for bending stress. Each parameter was tested for correlation with crotch strength within the individual species and for the three species combined. The ratio of branch diameter over crotch width had the highest correlation coefficient for crotch strength. Branch angle was also correlated with crotch strength but not as highly as the ratio of the diameters. V-shaped crotches (those with included bark) were significantly weaker than U-shaped crotches for all species. The ratio of the two stem diameters greatly influenced the manner in which the crotches broke. In crotches where the branch diameter was 2/3 the size of the trunk or smaller, the crotch broke by being pulled directly out of the trunk. Crotches with branches more than 2/3 the diameter of the trunk broke when the trunk split longitudinally and had significantly lower strength values. These results indicate that increased crotch strength results from a small branch diameter relative to that of the trunk.
Master of Science
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32

Amjad, Mohammed Amin Ben Abdul-Rauf. "Elasticity and strength of masonary, units and mortar." Thesis, University of Leeds, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.237248.

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Chemrouk, Mohamed. "Slender concrete deep beams : behaviour, serviceability and strength." Thesis, University of Newcastle upon Tyne, 1988. http://hdl.handle.net/10443/3103.

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Reinforced concrete deep beams have useful applications in construction. However, their design is not yet covered by the British Standard BS 8110: 1985 which explicitly states that "for the design of deep beams, reference should be made to specialist literature". A selection of literature on deep beams is considered. First, the major works that have led to design recommendations are reviewed. Then, the current major codes and manuals covering deep beams, namely the CIRIA Guide, the European CEB-FIP model code, the American ACI(318-83) (revised 1986) code and the Canadian CAN3-A22.3-MB4 code are outlined; worked examples are given in order to illustrate their practical applications and compare their different approaches to deep beam design. The purpose of this literature review was to define the deep beam problem and identify the major questions still remaining unanswered together with the limitations of the present design documents on the subject. The nature of diagonal cracking in slender deep beams has recently raised a question as to the application of the shear-strength equation in cl.3.4.2 of the CIRIA Deep Beam Guide. The effectiveness of web reinforcement on serviceability and strength of deep beams in general is also an area where strong disagreement exists. A testing programme, consisting of 15 beams of height/thickness ratios ranging from 20 to 50 and grouped in 3 different series, was performed to provide information on these two areas. The main variables were the height/thickness ratio and the quantity and arrangement of web steel. The beams were tested under concentrically applied two point-loads. Based on the test results and observations, modifications are given for the CIRIA equation and other formulae derived from stocky deep beam tests to be used in slender ones for analysis and design purposes. A new formula is also proposed for the prediction of the ultimate shear capacity. The stability of deep beams is another area which has received less attention in the past by researchers and designers who often avoided the problem by opting for stocky sections. To quote from the CIRIA Guide "as a possible criterion of failure, buckling can not be disregarded". However, information on such topic is very scarce in the literature. Currently, the only documents that provide design guidelines for buckling are the CIRIA Guide and the Portland Cement Association Design Aid, both of which are based on theoretical studies and engineering judgement. An experimental testing programme, consisting of 7 large scale beam-panels with height/thickness ratios in the range of 20 to 70 and a constant span/depth ratio of 1.0, provided buckling data against which the reliability of the two design documents was assessed. These tests confirmed that both documents offer a safe buckling design with the CIRIA Guide being too conservative. Although deep beams are frequently continuous over several spans, very little published data exist for such beams. For this purpose, 12 two-span continuous concrete deep beams with span/depth ratios less than 1.0 and having different quantities and arrangements of web reinforcement were tested under two point-loads. The specimens were heavily instrumented to obtain as much information as possible about the behaviour of the beams at each stage of loading. Applied loads and reactions were among the measurements made and enabled the actual bending moment distribution to be determined and compared to that of corresponding continuous shallow beams. Based on the test results and observations and in the light of other published work, recommendations are given for the bearing, shear and flexural design of continuous deep beams.
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Inegbenebor, A. O. "Structure-property relationships in some iron-manganese-molybdenum steels." Thesis, Bucks New University, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.380862.

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Khadka, Chandra. "PENALIZED REGRESSION MODELS FOR CONCRETE STRENGTH ESTIMATION." OpenSIUC, 2021. https://opensiuc.lib.siu.edu/theses/2818.

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Concrete compressive strength is one of the most important material properties affectingthe design of concrete structures. Strength that will be achieved once the concrete sets should be correctly predicted prior to pouring the concrete. Regression techniques can be used to calculate the 28-day concrete strength with a level of certainty. This thesis deals with the data modelling and analysis of 28-day compressive strength of high-performance concrete. Historical data on various mix compositions of high-performance concrete was obtained from University of California, Irvine repository. The data had 8 predictors and 1 response variable. In this thesis, three penalized regression approaches, namely, ridge, lasso, and elastic net were used to create a predictive model for compressive strength, and the performance of these model were compared to the traditional multiple linear regression model. Holdout sets from 2% to 40% at an increment of 2% were taken. Every regression algorithm was designed to conduct regression on 30 sets of randomly partitioned data. The performance of models was assessed using coefficient of multiple determination, RMSE, and residual plots. All regression techniques were able to predict the concrete strength with about 75% accuracy level.
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Bull, Peter H. "Damage tolerance and residual strength of composite sandwich structures." Doctoral thesis, KTH, Aeronautical and Vehicle Engineering, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3757.

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The exploitation of sandwich structures as a means toachieve high specific strength and stiffness is relatively new.Therefore, the knowledge of its damage tolerance is limitedcompared to other structural concepts such as truss bars andmonocoque plate solutions.

Several aspects of the damage tolerance of sandwichstructures are investigated. The influence of impact velocityonresidual strength is investigated. Sandwich panels withfaces of glass fiber reinforced vinylester are impacted bothwith very high velocity and quasi static. The residual strengthafter impact is found to be similar for both cases of impactvelocity.

Curved sandwich beams subjected to opening bending momentare studied. Faceñcore debonds of varying size areintroduced between the compressively loaded face sheet and thecore. Finite element analysis in combination with a pointstress criterion is utilized to predict the residual strengthof the beams. It is shown that it is possible to predict thefailure load of the beams with face-core debond.

Using fractography the governing mode of failure ofcompressively NCF-carbon is characterized. Sandwich panelssubjected to compression after impact are shown to fail byplastic micro buckling.

The residual compressive strength after impact of sandwichpanels is investigated. Sandwich panels with face sheets ofnon-crimp fabric (NCF) carbon are subjected to different typesof impact damages. Predictions of residual strength are madeusing the Budiansky, Soutis, Fleck (BSF) model. The residualstrength is tested, and the results are compared topredictions. Predictions and tests correlate well, and indicatethat the residual strength is dependent on damage size and notthe size of the damaged panel.

A study of the properties of a selection of fiberreinforcements commonly used in sandwich panels is conducted.The reinforcements are combined with two types of core materialand three types of matrix. Also the influence of laminatethickness is tested. Each combination materials is tested inuni-axial compression, compressive strength after impact andenergy absorption during quasi static indentation. Thespecimens which are tested for residual strength are eithersubjected to quasi-static or dynamic impact of comparableenergy level. Prediction of the residual strength is made andcorrelates reasonably whith the test results. The tests showthat if weight is taken into account the preferred choice offiber reinforcement is carbon.

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Singh, Mandeep. "Construction technique and strength of connected regolith bag structures." Auburn, Ala., 2007. http://repo.lib.auburn.edu/2007%20Spring%20Theses/SINGH_MANDEEP_3.pdf.

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Naderi, Mahmood. "Assessing the strength and durability of repaired concrete structures." Thesis, Queen's University Belfast, 1988. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.276362.

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Mood, Geoffrey I. "Weaving thick three-dimensional structures with high strength fibres." Thesis, University of Ulster, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.436203.

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Batt, C. "Optimising cathodic protection requirements for high strength steels in the marine environment." Thesis, Cranfield University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.323886.

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Jukes, Paul. "An investigation into the shear strength of masonry joints." Thesis, University of Sussex, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.482074.

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42

Davison, John Buick. "Strength of beam-columns in flexibly connected steel frames." Thesis, University of Sheffield, 1987. http://etheses.whiterose.ac.uk/1866/.

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This thesis describes an experimental study undertaken to examine the influence of joint resistance to in-plane moments on the performance of steel columns and complete frames. The principal objective of the tests was to provide experimental data against Which sophisticated computer analysis programs may be verified. Details of the experimental study of 22 joint tests, eight column subassemblages, and two three storey, two bay steel frames are reported. It is demonstrated that all beam to column connections have an inherent degree of stiffness and that their moment-rotation characteristics are non-linear. The load carrying capacity of columns, confined to buckle in-plane, is shown to be enhanced considerably by the resistance to rotation provided by simple beam to column connections. In frames incorporating flange cleat connections the beams and columns can sustain greater loading and deflect less than is predicted by current design models. The assumptions of pin-ended columns and simply supported beams are shown to be conservative. Comparisons of the results of the column and frame tests with two finite element analysis programs are presented. The use of computer programs for semi-rigid design as well as the development of a simple approach are discussed.
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43

Ashour, Ashraf Fawzy. "Behaviour and strength of reinforced concrete continuous deep beams." Thesis, University of Cambridge, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319339.

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44

Barzegar, Abdolrahman. "Structural stability and mechanical strength of salt-affected soils." Title page, contents and abstract only, 1995. http://web4.library.adelaide.edu.au/theses/09PH/09phb296.pdf.

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Copies of author's previously published articles in pocket inside back cover. Bibliography: leaves 147-160. This thesis outlines the factors affecting soil strength and structural stability and their interrelationship in salt-affected soils. The objectives of this study are to investigate the influence of clay particles on soil densification and mellowing, the mellowing of compacted soils and soil aggregates as influenced by solution composition, the disaggregation of soils subjected to different sodicities and salinities and its relationship to soil strength and dispersible clay and the effect of organic matter and clay type on aggregation of salt-affected soils.
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45

Kolios, Athanasios. "A multi-configuration approach to reliability based structural integrity assessment for ultimate strength." Thesis, Cranfield University, 2010. http://dspace.lib.cranfield.ac.uk/handle/1826/5717.

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Structural Reliability treats uncertainties in structural design systematically, evaluating the levels of safety and serviceability of structures. During the past decades, it has been established as a valuable design tool for the description of the performance of structures, and lately stands as a basis in the background of the most of the modern design standards, aiming to achieve a uniform behaviour within a class of structures. Several methods have been proposed for the estimation of structural reliability, both deterministic (FORM and SORM) and stochastic (Monte Carlo Simulation etc) in nature. Offshore structures should resist complicated and, in most cases, combined environmental phenomena of greatly uncertain magnitude (eg. wind, wave, current, operational loads etc). Failure mechanisms of structural systems and components are expressed through limit state functions, which distinguish a failure and a safe region of operation. For a jacket offshore structure, which comprises of multiple tubular members interconnected in a three dimensional truss configuration, the limit state function should link the actual load or load combination acting on it locally, to the response of each structural member. Cont/d.
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Yi, Sŏk-wŏn. "Influence of surface topography on interface strength and counterface soil structure." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/19559.

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47

He, Chunxia 1968. "Shear flow behavior and molecular structure of high melt strength polypropylenes." Thesis, McGill University, 2003. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=84208.

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Linear shear flow behavior and molecular structure studies were carried out on linear polypropylenes produced using Ziegler-Natta catalysts and sets of branched polypropylenes produced from these linear precursors.
A method combining dynamic and creep measurements was employed to obtain a complete picture of the linear viscoelastic behavior of these polypropylenes. It was found that all samples in a set of polypropylenes have the same linear viscoelastic behavior in the high-frequency range, but display dramatic differences at low frequencies. Increasing branching level results in a steep increase of the zero-shear viscosity, an increase of the steady-state compliance, and a broadening of the relaxation spectrum whose shape changes dramatically and peaks shift to longer times.
Molecular models were tested and applied to the linear polypropylenes to predict linear viscoelastic properties from the molecular weight distribution (MWD). The parameters obtained from the best fit of predicted and experimental data of linear polypropylenes were used to calculate a fictive relaxation spectrum for branched polymers from their MWDs as if they were linear. The comparison between this predicted result and the experimental spectrum showed the separate effects of polydispersity and branching on rheology.
To obtain detailed structural information, the branching process of polypropylenes was simulated using a Monte-Carlo approach, which provides detailed information such as MWD and branching distribution. The simulated MWD was adjusted to the measured GPC curve using a single parameter simply related to the branching density lambda (LCB/1000C). Relations between branching parameters and moments of the MWD were determined, which offer the possibility to calculate branching parameters directly from GPC results. The branching efficiency was estimated and correlations between engineering properties of polypropylenes and the structural information were obtained, which is of valuable industrial interest for polymer design.
A determination of the weight fractions of branches and segments between branch points from the relaxation spectrum is proposed. Due to the complexity of molecular relaxation mechanisms, only approximate correlations between molecular architecture and rheology were observed.*
*This dissertation is a compound document (contains both a paper copy and a CD as part of the dissertation). The CD requires the following system requirements: Microsoft Office.
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Gao, Xiao. "Tailored interphase structure for improved strength and energy absorption of composites." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 5.63 Mb., 321 p, 2006. http://proquest.umi.com/pqdlink?did=1172119431&Fmt=7&clientId=79356&RQT=309&VName=PQD.

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Wilson, R. C. "Welded airframes : static strength, structural design and analysis." Thesis, Queen's University Belfast, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.546430.

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50

Friis, Jesper. "Structural performance of confined high strength concrete columns." Thesis, City University London, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.397864.

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