Dissertations / Theses on the topic 'Sandwich structure'
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Violette, Michael A. "Fluid structure interaction effect on sandwich composite structures." Thesis, Monterey, California. Naval Postgraduate School, 2011. http://hdl.handle.net/10945/5533.
Full textThe objective of this research is to examine the fluid structure interaction (FSI) effect on composite sandwich structures under a low velocity impact. The primary sandwich composite used in this study was a 6.35-mm balsa core and a multi-ply symmetrical plain weave 6 oz E-glass skin. The specific geometry of the composite was a 305 by 305 mm square with clamped boundary conditions. Using a uniquely designed vertical drop-weight testing machine, there were three fluid conditions in which these experiments focused. The first of these conditions was completely dry (or air) surrounded testing. The second condition was completely water submerged. The final condition was a wet top/air-backed surrounded test. The tests were conducted progressively from a low to high drop height to best conclude the onset and spread of damage to the sandwich composite when impacted with the test machine. The measured output of these tests was force levels and multi-axis strain performance. The collection and analysis of this data will help to increase the understanding of the study of sandwich composites, particularly in a marine environment.
Sander, Tavallaey Shiva. "Wave propagation in sandwich structure." Doctoral thesis, KTH, Vehicle Engineering, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3088.
Full textTran, Van Luan. "Etude du comportement hygro-thermo-mécanique d'un matériau composite sandwich avec âme balsa utilisé en applications navales." Nantes, 2013. http://www.theses.fr/2013NANT2001.
Full textSandwich composite structures have been widely adopted in the naval field because they exhibit both lightness and good mechanical strength. However, their resistance to moisture in the marine environment is difficult to predict, and their fire resistance is one of the main limitations to their use in a greater number of cases. In this work, we focus on the behavior of a composite sandwich composed with glass-polyester skins and balsa core. Balsa, which is the main constituent, can absorb a large amount of water which may affect its mechanical properties. Moreover, the presence of moisture can influence the fire resistance of the material. Thus, in order to highlight the material durability and the physical phenomena encountered, several experiments were performed in miscellaneous conditions of humidity, temperature and mechanical loadings. In addition to classical results obtained on the balsa, testing of fire resistance combined with bending tests on sandwich composite materials were achieved to estimate the residual strength as a function of the combustion time. Finally, from experimental results related to the water uptake of balsa and of sandwich composite, modelling was computed to better understand and predict the mechanical state of the studied sandwich structure
Hui, Yi. "Development and experimental validation of vibration based damage indicator on a specific twin-wall sandwich structure." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEC032.
Full textStructural health monitoring (SHM) has attracted much attention in many engineering fields like civil, aeronautic, mechanical industry, etc. since it is important to monitor the healthy condition of the operational structure in order to avoid unpredicted structural failure which may have severe consequences. The four-level damage identification process: existence, localization, severity and prediction of damage evolution, can be partly realized if a suitable indicator is chosen. It exists different damage indicators whose application range of frequency spans from vibrational response at low frequencies to the ultrasonic regimes in the mega hertz range.The sandwich structures are widely used in various engineering applications due to its exceptionally high flexural stiffness-to-weight ratio compared to monocoque structures. In this thesis a specified twin-wall sandwich structure in polypropylene was studied and vibration-based indicators were designed by taking use of its relative high damping and propagation directivity characteristics. Numerical investigations on different damage scenarios (i.e., different types of defect and their combinations) and an associated discussion on the range of application were first carried out. Experimental configuration was easily realized with the help of a scanning laser doppler vibrometer (SLDV). Defect was successfully detected by the proposed indicators
Zhang, Shufeng. "Thermomechanical interaction effects in polymer foam cored sandwich structure." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/351349/.
Full textBesse, Camille. "Development and optimization of a formable sandwich sheet." Phd thesis, Palaiseau, Ecole polytechnique, 2012. https://theses.hal.science/docs/00/69/12/46/PDF/These_Camille_Besse.pdf.
Full textThis thesis investigates the mechanical behavior of a new type of formable all-metal bi-directionally corrugated sandwich sheet material. Unlike conventional flat sandwich panel materials, this type of sandwich sheet material can be formed into three-dimensional shapes using traditional sheet metal forming techniques. In a first step, the core structure geometry is optimized such as to offer the highest shear stiffness-to-weight ratio. The post yielding behavior of the "optimal" sandwich structure is investigated using finite elements simulations of multi-axial experiments. A phenomenological constitutive model is proposed using an associative flow rule and distortional hardening. An inverse procedure is outlined to describe the sandwich material model parameter identification based on uniaxial tension and four-point bending experiments. In addition, simulations of a draw bending experiment are performed using a detailed finite element model as a well as a computationally-efficient composite shell element model. Good agreement of both simulations is observed for different forming tool geometries which is seen as a partial validation of the proposed constitutive model
Besse, Camille. "Development and optimization of a formable sandwich sheet." Phd thesis, Ecole Polytechnique X, 2012. http://tel.archives-ouvertes.fr/tel-00691246.
Full textBarré, Sébastien. "Optimisation d'une structure sandwich dans le cadre d'une utilisation structurelle ferroviaire." Compiègne, 1996. http://www.theses.fr/1996COMPD964.
Full textVinhas, Bertolini Peter. "Modélisation des poutres sandwich elasto-piézo-électriques : élément fini raffiné." Paris, ENSAM, 2001. http://www.theses.fr/2001ENAM0001.
Full textWilhelm, Arnaud. "Développement d’une méthodologie pour la compréhension du comportement et le dimensionnement d’un bouclier sandwich soumis à l’impact d’un oiseau." Thesis, Toulouse, ISAE, 2017. http://www.theses.fr/2017ESAE0005/document.
Full textDuring an aircraft flight, the possible collision with a bird is a major threat, and the certification authorities require to take ît into account. In the case of a nose strike, the pressurized bulkhead is protected by a shield. Understanding the behaviour under impact of such a sandwich structure is essential. This work has two main goals: understanding the design parameters influence on the shield behaviour, and propose a methodology to conduct this study. Firstly, a generic finite element model is created to be used in a parametric study. A tool to measure the shield deformation is proposed to make it possible to easily compare the behaviour of different shields and to help understanding the behaviour of a shield. This tool is based on the projection ofthe shield deformation on a basis comprising three modes: Indentation, Bendîng and Crushing. A screening study is then conducted to rank the design parameters with respect to their influence. A parametric study is then conducted on the six first parameters. A Latin hyper-square is used for the design of experiment and seven different quantifies are studied. The Gaussian processes framework is used to create surrogates models. Global sensitivity analyses are then conducted to study the variation of the shield behaviour in the whole design space. The effects of each parameterare measured and explained. Finally, a method to minimize the shield mass, using the surrogate models to enforce minimal target protection criteria, is presented
Evteev, Alexander V., Elena V. Levchenko, Irina V. Belova, and Graeme E. Murch. "Formation of a surface–sandwich structure in Pd-Ni nanoparticles by interdiffusion: Formation of a surface–sandwich structure in Pd-Ni nanoparticlesby interdiffusion: atomistic modelling." Diffusion fundamentals 6 (2007) 18, S. 1-2, 2007. https://ul.qucosa.de/id/qucosa%3A14192.
Full textIu, Vai-pan. "Nonlinear vibration analysis of multilayer sandwich structure by incremental finite elements /." [Hong Kong : University of Hong Kong], 1985. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12322945.
Full textRiccò, Federico. "Design and engineering of 100% polyurethane sandwich structure for sanitary application." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
Find full textIu, Vai-pan, and 姚偉彬. "Nonlinear vibration analysis of multilayer sandwich structure by incremental finite elements." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1985. http://hub.hku.hk/bib/B31230623.
Full textLundgren, Eric Charles. "Durable Sandwich Structure Joining Technology for NASA's Ares V Launch Vehicle." Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/79693.
Full textMaster of Science
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.
Full textThe 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.
Berkowitz, Charles Kyle. "Characterization of the debonding of graphite/epoxy-nomex honey comb sandwich structure." Thesis, Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/18188.
Full textShipsha, Andrey. "Failure of Sandwich Structures with Sub-Interface Damage." Doctoral thesis, Stockholm, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3184.
Full textBail, Justin L. "Non-desctructive investigation & FEA correlation on an aircraft sandwich composite structure." Akron, OH : University of Akron, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=akron1196702586.
Full text"December, 2007." Title from electronic thesis title page (viewed 02/25/2008) Advisor, Wieslaw Binienda; Faculty readers, Craig Menzemer, Robert Goldbert; Department Chair, Wieslaw Binienda; Dean of the College, George K. Haritos; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.
McCrillis, Ryan D. "Dynamic failure of sandwich beams with fluid-structure interaction under impact loading." Thesis, Monterey, California. Naval Postgraduate School, 2010. http://hdl.handle.net/10945/5101.
Full textThe objective of this research is to examine the added mass effect that water has on the dynamic response of a sandwich composite under impact, particularly impact leading to failure. Because sandwich composites are much less dense than water, fluid structure interaction plays a large part in the failure. Composite samples were constructed using vacuum assisted transfer molding, with a 6.35 mm balsa core and symmetrical plain weave 6 oz E-glass skins. The experiment consisted of three phases. First, using threepoint bending, strain rate characteristics were examined both in air and under water. After establishing that the medium had no effect on the beam response under different strain rates, but confirming that previously established relationships between strain rate and ultimate strength for axially loaded glass composites can be applies to sandwich construction in bending, the experiment progressed to impact testing where each specimen, again a one inch wide beam, was subjected to progressively increasing force. The data from this phase showed that submerged samples failed at lower drop heights and lower peak forces with a failure mode dominated by center span skin compression failure. Beams in air were able to withstand higher drop heights and peak forces. Dry sample failure mode was dominated by skin compression failure at the clamped support with occasional evidence of shear failure through the core adjacent to the clamped support. The data from this study will increase understanding of sandwich composite characteristics subjected to underwater impact.
Evteev, Alexander V., Elena V. Levchenko, Irina V. Belova, and Graeme E. Murch. "Formation of a surface–sandwich structure in Pd-Ni nanoparticles by interdiffusion." Universitätsbibliothek Leipzig, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-193359.
Full textHODAR, FRANCOIS. "Caracterisation et modelisation d'une structure sandwich, deformee par une ceramique piezoelectrique pzt." Besançon, 1996. http://www.theses.fr/1996BESA2017.
Full textBail, Justin. "Non-Destructive Investigation & FEA Correlation on an Aircraft Sandwich Composite STructure." University of Akron / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=akron1196702586.
Full textAllaoui, Samir. "Etude et modélisation d'un comportement de structure sandwich de type carton ondulé." Compiègne, 2005. http://www.theses.fr/2005COMP1588.
Full textThe principal function of packing is to protect what it sells and to sell what it protects. One of the more used packing is the corrugated cardboard. This is due to its numerous advantages notably the protection of the environment (completely recyclable) and its reduce coast. Nevertheless, its use in optimum manner requires the apprehension of its mechanical behavior. This study proposes to consider the corrugated cardboard sandwich as a monolithic material. The adopted approach is divided in two parts. First experimental procedures adapted to this material, ared developed in order to identify the homogenized elastic parameters and the phenomena governing its behavior. Then an analytical model is established to predict the elastic and nonlinear behavior in the plane according to the structural parameters. This approach makes it possible to simplify numerical computations
Styles, Millicent, and milli styles@anu edu au. "Characterisation of the flexural behaviour of Aluminium Foam Sandwich Structures." The Australian National University. Faculty of Engineering and Information Technology, 2008. http://thesis.anu.edu.au./public/adt-ANU20080813.170807.
Full textWang, Jinghui. "Fabrication, Characterization and Simulation of Sandwich Structure GaN Schottky Diode Ionizing Radiation Detectors." The Ohio State University, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=osu1405497243.
Full textTom, Louis-Georges. "Contribution à l'étude numérique de la propagation d'un défaut de collage dans une structure sandwich Nida." Thesis, Le Mans, 2014. http://www.theses.fr/2014LEMA1036/document.
Full textSAFRAN Aircelle manufactures sandwich structures made of composite skins bonded to aluminium honeycomb core for aircraft’s engines nacelles applications. Local disbonds may occur at the skins/core interface and lead to significant strength reduction under in-service loadings. The present work was done with ISMANS and SAFRAN Aircelle and deals with the introduction of a “Virtual Testing” approach in order to reduce substantiation and validation cost of sandwiches structures with embedded disbond.In this study we have two kinds of models at two scales to describe the sandwich behaviour: the “homogeneized” model, which provide an industrial tool for design offices and the “detailed” model, which provide a specific tool for accurate analysis of disbond growth initiation at skin/core interface. Due to the numerical cost of the second type of model, the superelement technique has been successfully used which permits to gain computational costs without altering the result quality.Damage mechanics, with cohesive zone elements, have been chosen to numerically determine the disbond growth threshold after a comparative study with linear fracture mechanics and a full experimental method. Inputs data for industrial code using cohesive zone elements have been studied through an experimental investigation. DCB type tests on reinforced sandwiches were perfomed in order to determine the energy release rate at the skin/core interface. Various mode-mixity and pure opening mode are available using the same testing tool. The latter has been successfully modelled
Yang, Bing. "Thermoplastic and Thermoset Natural Fiber Composite and Sandwich Performance." Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc500002/.
Full textLedi, Koffi Sénanou. "Approche inverse pour l’identification des propriétés viscoélastiques de structures sandwichs amorties." Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0250/document.
Full textIn this work, a inverse identification method of the mechanical properties of the viscoelastic material (shear modulus and loss factor) functionalized in a sandwich structure with three symmetrical layers is proposed. The objective of this work is to be able to identify the mechanical properties in situ. Through a finite element model based on Rao's Zig-Zag model, our model ensures the modal parameter determination of the sandwich beam. The inverse approach consists of an iterative procedure that determines the mode shapes given the material parameters and then calculates the viscoelastic properties from the modes using a Rayleigh quotient until convergence on the properties of the material is satisfied. The input parameters of the inverse model are the resonance frequencies and loss factors of the sandwich beam obtained experimentally. As a result, the frequency dependence of the viscoelastic properties of the sandwich beam is determined by an automated way. The method has been successfully compared to Ross-Kerwin-Ungar formulas; a standard optimization approach and the literature. From the results, we have been able to deduce the constitutive laws of the viscoelastic heart according to rheological models such as the generalized Maxwell model, ADF, GHM and fractional Zener. This experimental device coupled to the method of identification allowed the investigation of modal parameters of the beam at different temperatures to study the effect of the temperature on the rheological laws. To study the robustness of our method, we carried out tests repeatability, reproducibility on a sample population. Since the effectiveness of our method has been proven, a sensitivity study has been carried out on the geometrical characteristics of our structure and the input parameters. The results obtained show the strong impact of certain parameters on identification
Salem, Adel I. "Weight and Cost Multi-Objective Optimization of Hybrid Composite Sandwich Structures." University of Dayton / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1478637482819839.
Full textLedi, Koffi Sénanou. "Approche inverse pour l’identification des propriétés viscoélastiques de structures sandwichs amorties." Electronic Thesis or Diss., Université de Lorraine, 2018. http://www.theses.fr/2018LORR0250.
Full textIn this work, a inverse identification method of the mechanical properties of the viscoelastic material (shear modulus and loss factor) functionalized in a sandwich structure with three symmetrical layers is proposed. The objective of this work is to be able to identify the mechanical properties in situ. Through a finite element model based on Rao's Zig-Zag model, our model ensures the modal parameter determination of the sandwich beam. The inverse approach consists of an iterative procedure that determines the mode shapes given the material parameters and then calculates the viscoelastic properties from the modes using a Rayleigh quotient until convergence on the properties of the material is satisfied. The input parameters of the inverse model are the resonance frequencies and loss factors of the sandwich beam obtained experimentally. As a result, the frequency dependence of the viscoelastic properties of the sandwich beam is determined by an automated way. The method has been successfully compared to Ross-Kerwin-Ungar formulas; a standard optimization approach and the literature. From the results, we have been able to deduce the constitutive laws of the viscoelastic heart according to rheological models such as the generalized Maxwell model, ADF, GHM and fractional Zener. This experimental device coupled to the method of identification allowed the investigation of modal parameters of the beam at different temperatures to study the effect of the temperature on the rheological laws. To study the robustness of our method, we carried out tests repeatability, reproducibility on a sample population. Since the effectiveness of our method has been proven, a sensitivity study has been carried out on the geometrical characteristics of our structure and the input parameters. The results obtained show the strong impact of certain parameters on identification
Teston, Bénédicte. "Comportement thermique des structures sandwich pour application dans les capots moteurs d'hélicoptères." Paris. ENSAM, 2002. http://www.theses.fr/2002ENAM0010.
Full textKhasawneh, Firas Abdallah. "Characterization of drillability of sandwich structure of carbon fiber reinforced epoxy composite over titanium alloy." Diss., Columbia, Mo. : University of Missouri-Columbia, 2006. http://hdl.handle.net/10355/5871.
Full textThe entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on September 13, 2007). Vita. Includes bibliographical references.
Iwai, Kento. "Synthesis and Properties of Zwitterionic Compounds Utilizing an Introducing Unit of a Boranuidyl Group." Doctoral thesis, Kyoto University, 2021. http://hdl.handle.net/2433/263481.
Full textLéotoing, Lionel. "Modélisation du flambage global, local et interactif dans les structures sandwich en compression." Saint-Etienne, 2001. http://www.theses.fr/2001EMSE0020.
Full textSandwich structures exhibit a high specific flexural stiffness but also a complex mechanical behaviour. This last point is emphasized when in-plane compression is considered. Indeed, geometrical instabilities can appear at the global scale of the structure or at the local scale of the components (core and skins). The aim of this thesis is to model analytically and numerically the global and local buckling of a sandwich beam, but also the possible interactions between instabilities at these two scales. First, an analytical beam model based on a high order theory is established, which permits to isolate the critical loads associated with global buckling and symmetrical and antisymmetrical wrinkling of skins. Thanks to these loads, design diagrams are built which are useful to quickly identify sandwich beam configurations locally or globally unstable. Moreover, this analytical model is successfully used to characterize the apparition and the stability of an interactive buckling form. Then, a "simplified" FE model is built which permits to find a good correlation between the numerical and the previous analytical results. The low time-consuming calculation of this model leads to an efficient characterization of the complete response of the sandwich beam in a material and/or geometrical nonlinear framework. The stability of the different buckling forms are discussed, as well as the high sensitivity towards global or local geometrical imperfections. The introduction of an elastoplastic constitutive law leads to a very sub-critical response, characterized by a drop in the global stiffness of the beam due to the localization of plastic strains
Essid, Safa. "Sandwiches à fibres de lin et anas de lin : optimisation structure-imprégnation-propriétés." Thesis, Normandie, 2020. http://www.theses.fr/2020NORMLH05.
Full textFor different reasons including ecological ones, the weight reduction of structures and valorization of lignocellulosic biomass are considered as possible solutions towards ustainable innovation. In this context, the work of this thesis focuses on the manufacturing and optimization of sandwich structures with skins reinforced with flax fibers with mechanical, economic and environmental goals. A flax plant by-product called flax shives is valued by the development of agglomerated panels. These panels will serve as a core for the sandwich structures. To reach the optimization stage, experimental characterizations of the matrix and core materials are carried out first. Subsequently, joint work between the production processes and the desired properties of sandwich structures is undertaken. All the characteristics determined are compared with those of a non-bio-sourced reference material. Finally, analytical, graphic and numerical approaches are developed in order to answer the main question related to the optimization of the design of flax based sandwich structures with imposed rigidity and resistance to rupture. This optimization procedure should systematically control the desired characteristics of flax sandwiches
Ward, Charles. "Modification of a Ground Based Atomic Oxygen Simulation Apparatus to Accommodate Three Dimensional Specimens." DigitalCommons@CalPoly, 2018. https://digitalcommons.calpoly.edu/theses/1850.
Full textBrown, Richard A. "The synthesis, structure and characterisation of some iron sandwich complexes and their application to organic synthesis." Thesis, University of Essex, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.332412.
Full textSaifullah, Abu Naser Muhammad. "Fracture properties analysis of rotationally moulded plastics for their application in skin-foam-skin sandwich structure." Thesis, Bournemouth University, 2017. http://eprints.bournemouth.ac.uk/29483/.
Full textVo, Hoang Nhi. "Development of an Innovative Meta-Panel Sandwich Core for Structure Protection against Blast and Impact Loads." Thesis, Curtin University, 2022. http://hdl.handle.net/20.500.11937/89452.
Full textGandy, Helene Tchoutouo Ndjountche. "Adhesiveless honeycomb sandwich structure with carbon graphite prepreg for primary structural application: a comparative study to the use of adhesive film." Thesis, Wichita State University, 2012. http://hdl.handle.net/10057/5388.
Full textThesis (M.S.)--Wichita State University, College of Engineering, Dept. of Mechanical Engineering
Almusawi, Aqil mousa. "Mise en œuvre et optimisation des propriétés d'une structure sandwich en matériaux biosourcés (fibres et bois de chanvre) avec une matrice en polystyrène expansé pour le bâtiment." Thesis, Bourgogne Franche-Comté, 2017. http://www.theses.fr/2017UBFCA009/document.
Full textDue to the rapidly improving functionality of building materials, and increasingly complicated human resource management issues, the traditional cement-based building materials of the past are becoming less and less desirable.These outdated materials are being replaced by new structures of wall that better optimize choices of materials and their layouts. In this study, we propose a multi-function structure to be the unit of a typical wall (individual house), which can be produced via the use of inexpensive materials and classic manufacturing processes. To achieve this, we chose the renewable agricultural source of the hemp plant (hemp yarns and hemp shive particles), along with recycled expanded polystyrene, to manufacture a fully recyclable composite. We established a relationship between the physical-mechanical properties of the resulting composite and the parameters of the manufacturing process, particularly in the zone of high load reinforcement, we successfully manufactured a composite of 100% hemp shive particles. In addition, we have also prepared the numerical optimization phase of an alveolar sandwich structure by modeling the process and the obtained structure
Bunyawanichakul, Phacharaporn. "Contribution à l'étude du comportement des inserts dans les structures sandwichs composites." Toulouse, ENSAE, 2005. http://www.theses.fr/2005ESAE0012.
Full textFindley, Tara M. "An Experimental Analysis of Auxetic Folded Cores for Sandwich Structures Based on Origami Tessellations." University of Toledo / OhioLINK, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1372862614.
Full textChatti, Fadhel. "Simulations numériques du comportement mécanique d'un matériau d’âme à base de fibres enchevêtrées destiné aux applications aéronautiques." Thesis, Toulouse, ISAE, 2018. http://www.theses.fr/2018ESAE0040/document.
Full textA new core material based on entangled and cross-linked fibers has been previously developed in order to improve certain properties of sandwich structures including vibration damping. However, its behavior must be optimized for use in the aerospace field. Several morphological parameters can be modified during the manufacturing process. The aim of this thesis was to develop a numerical model to better understand the behavior of this entangled cross-linked material. The behavior of a representative volume element of entangled carbon fibers without cross-links is first studied in compression using finite element. The numerical geometry of the fiber network relies on the morphological parameters of a real sample. Numerical simulations make it possible to follow, during the confined compression, the evolution of the different parameters, such as the distribution of fiber orientations, the distance between contacts or the volume fraction. These results provide a robust basis for developing the numerical model of the entangled cross-linked material which is then used to model the mechanical behavior in shear, and in particular to simulate and explain the hysteresis loops observed experimentally. At the end of this work, a numerical study is proposed to study the influence of different morphological parameters on the compressive stiffness and shear stiffness of the entangled cross-linked material
Strehler, Frank, Marcus Korb, and Heinrich Lang. "Crystal structure of ruthenocenecarbonitrile." Universitätsbibliothek Chemnitz, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-166700.
Full textDel, Broccolo Simone. "Effets de la topologie des cellules d'une structure en nid d'abeille." Thesis, Bourgogne Franche-Comté, 2020. http://www.theses.fr/2020UBFCD001.
Full textHoneycomb sandwich panels are well known to provide interesting static out of plane properties because of their high equivalent stiffness whilst containing mass and for this reason, they are widely used as a ‘building brick’ in the Aerospace, Automotive and Naval industries. The environment in which these materials operate involve external forces which excites them in the mid-low frequency range. However, while a high stiffness/mass ratio is a desirable static property, the vibration frequency domain is usually in the high range and therefore they become poor mechanical and acoustic insulators within the frequency range they are usually subjected to. The question addressed then is simple: how periodic concepts can improve the broadband vibroacoustic signatures and performances of those structures? Most of vibroacoustic solutions are frequency band limited, specific and usually include the addition of mass, which for certain engineering segments is disadvantageous. Including vibroacoustic design rules at early stage of product development is one of the main research targets to improve their performance and would allow to design tuned structures without any later intervention or mass increment. This work focuses on investigating existing sandwich panel core topologies and attempt to create novel improved structures. The research was carried out trying to maintain the desired structural properties which justifies the usage of such solution in the first place but also considering its potential use as a platform for Multiphysics resonating periodic material inserts. Such cellular cores were manufactured using Kirigami, which is a variation of Origami, an ancient Japanese technique that consists in creating 3D structures by folding a 2D sheet of material. This manufacturing technique can be used as a systematic way to produce general honeycomb configurations with off-the-shelf long fibre composites by thermoforming and/or autoclaving. The main indicator on which I will focus to evaluate the vibroacoustic performance of the proposed innovative topologies will be the number and range of stopbands, also known as a bandgaps, which describe the frequency ranges in which elastic waves are not transmitted within the structure, in combination with the constituent material and its damping properties. This manuscript is organised in five chapters. The first one consists of a brief overview on periodic structures in the various engineering domains. Emphasis on Sandwich panels and their most popular manufacturing techniques will also be described. The second chapter will introduce the reader to the concept of elastic wave propagation in periodic media. Also, phenomena like Bragg or resonant bandgaps will be explained as well as the Floquet-Bloch theory applied to macro-scale structures such as aeronautical cellular cores.[...]
IURLARO, LUIGI. "Development of refined models for multilayered composite and sandwich structures: analytical formulation, FEM implementation and experimental assessment." Doctoral thesis, Politecnico di Torino, 2015. http://hdl.handle.net/11583/2606162.
Full textNjilie, Adamou Franck Éric. "Modélisation et évaluation de l'amortissement de structures sandwichs." Paris 6, 2002. http://www.theses.fr/2002PA066276.
Full textGulla-Cazenave, Jean. "Étude de l'influence des paramètres d'élaboration par infusion de résine liquide sur l'endommagement et le comportement à l'impact de matériaux composites à structure sandwich." Thesis, Toulouse 3, 2018. http://www.theses.fr/2018TOU30313.
Full textIn a previous study, prototypes for heavy military equipment (>600kg) transportation by helicopters were developed. Based on sandwich composite structures, these materials showed promising results in terms of weight reduction and load bearing capabilities, but weaknesses were observed during low velocity/low energy impact solicitations. During this PhD project, we aimed at optimizing sandwich structure's resistance to impacts, by studying elaboration parameter's influences of an industrial production method on impact behaviors. A bibliographic review showed critical parameters for this project's feasibility. We chose to use the Liquid Resin Infusion as the elaboration process; this technique is commonly used in the industry, and is suited for small production structures. State of the art also showed impact resistance improving methods for sandwich structures, in terms of processing conditions. A particular elaboration method was designed, to produce sandwich structures in a one-shot process. In this study, and with this method, four sets of parameters were selected: elaboration temperatures, matrix types, core's surface nature, and whether or not the matrix contained nanoscaled additives. Several combinations of these parameters were used to produce sandwich panels, which were cut in samples, to be impacted on a drop-weight tower. Preliminary testing allowed to determine representative impact conditions, similar to real-life situations, the observation and characterization techniques of damages, and behavior observation methods during impact. Based on that, we were able to identify three behaviors during impact, and four damage types, over all tested samples. These behaviors and damages were linked to the selected elaboration conditions and one set appeared very promising. The analysis of the parameters allowed us to understand the mechanisms occurring during the production of the panel. Residual resistance after impact was characterized by subjecting the samples to consecutive impacts. Four behaviors were observed, directly linked to the damages initially observed. The choice of an optimal structure was confirmed