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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Prediction of bearing failure in pin-loaded laminates

Ujjin, Rapee, Mechanical & Manufacturing Engineering, Faculty of Engineering, UNSW January 2007 (has links)
This thesis presents the results of an investigation of bearing failure at a loaded hole in carbon fibre composite laminates. The investigation included finite element analysis and a program of experimental testing for quasi-isotropic laminates, uni-directional laminates and laminates with fibres steered along predefined trajectories. The investigation formed part of a research program in the Cooperative Research Centre for Advanced Composite Structures Ltd (CRC-ACS) support by the Office of Naval Research from the United States. Work in progress in the CRC includes research defined in this thesis including the addition of nano-particles to the resin to improve the bearing strength. The literature survey undertaken in this thesis identified that the micro-buckling theory proposed by Professor C.T. Sun from Purdue University, Indiana USA, is the best analysis procedure for initial bearing failure in pin-loaded laminates. This failure theory has therefore been implemented in a Fortran program using the results from a finite element analysis for the nonlinear contact problem of a pin bearing on a hole in a composite laminate. The finite element analysis is executed using the commercial finite element system MSC.MARC. The numerical predictions have been validated by a test of progressive failure with the aid of an acoustic emission monitoring system. The acoustic emission parametric and frequency analysis is performed using the acoustic emission software Vallen Systeme. Fast fourier transformation of the waveform have been achieved to distinguish and identify microfailure mode. Failure mechanisms have been verified by post-mortem microstructural examination. There are 3 failure mechanisms associated with bearing failure in carbon fibre reinforced epoxy composite, the first is fibre matrix interfacial failure, followed by fibre fracture, and subsequently matrix splitting. The application of AE technique has been applied successfully to characterise the development of failure.
2

Finite element damage modeling of plain weave fabrics

Sikkil, Kaarthik K. January 2003 (has links)
Thesis (M.S.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains ix, 101 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 83-85).
3

Prediction of bearing failure in pin-loaded laminates

Ujjin, Rapee, Mechanical & Manufacturing Engineering, Faculty of Engineering, UNSW January 2007 (has links)
This thesis presents the results of an investigation of bearing failure at a loaded hole in carbon fibre composite laminates. The investigation included finite element analysis and a program of experimental testing for quasi-isotropic laminates, uni-directional laminates and laminates with fibres steered along predefined trajectories. The investigation formed part of a research program in the Cooperative Research Centre for Advanced Composite Structures Ltd (CRC-ACS) support by the Office of Naval Research from the United States. Work in progress in the CRC includes research defined in this thesis including the addition of nano-particles to the resin to improve the bearing strength. The literature survey undertaken in this thesis identified that the micro-buckling theory proposed by Professor C.T. Sun from Purdue University, Indiana USA, is the best analysis procedure for initial bearing failure in pin-loaded laminates. This failure theory has therefore been implemented in a Fortran program using the results from a finite element analysis for the nonlinear contact problem of a pin bearing on a hole in a composite laminate. The finite element analysis is executed using the commercial finite element system MSC.MARC. The numerical predictions have been validated by a test of progressive failure with the aid of an acoustic emission monitoring system. The acoustic emission parametric and frequency analysis is performed using the acoustic emission software Vallen Systeme. Fast fourier transformation of the waveform have been achieved to distinguish and identify microfailure mode. Failure mechanisms have been verified by post-mortem microstructural examination. There are 3 failure mechanisms associated with bearing failure in carbon fibre reinforced epoxy composite, the first is fibre matrix interfacial failure, followed by fibre fracture, and subsequently matrix splitting. The application of AE technique has been applied successfully to characterise the development of failure.
4

Laminated and hybrid soft body armor for ballistic applications

Kocer, Hasan Basri, Broughton, Roy. January 2007 (has links) (PDF)
Thesis(M.S.)--Auburn University, 2007. / Abstract. Vita. Includes bibliographic references.
5

The use of thermoplastic starch for the modification of hydrophilic breathable membranes

Pecku, Suven. January 2009 (has links)
Thesis (M.Eng.(Chemical Engineering))--University of Pretoria, 2006. / Summary in English. Date on t.p. of paper copy different (2007). Includes bibliographical references.
6

Quasi-three-dimensional woven composites

Rosario, Kirit Keith. January 2008 (has links)
Thesis (M.S.)--Michigan State University. Dept. of Mechanical Engineering, 2008. / Title from PDF t.p. (viewed on July 29, 2009) Includes bibliographical references (p. 108-110). Also issued in print.
7

Comportement mécanique de tissus à voiles, en fibres synthétiques, sous sollicitations biaxiales et déformation finie / Mechanical behavior of sailcloth materials, with synthetic fibers, under biaxial loadings and finite strain

Dib, Wassim 11 March 2014 (has links)
Ce travail concerne l'étude théorique, expérimentale et numérique du comportement mécanique de matériaux tissés et de toiles laminées à base de fibres synthétiques, destinés à la fabrication des voiles, comme le polyester ou le Kevlar. Une approche théorique originale a été proposée ; elle permet une prise en compte du comportement spécifique des fils, de l'enduction et de leurs interactions. La modélisation, qui en résulte, permet de décrire le comportement biaxial des matériaux tissés et des toiles, en chargements cycliques complexes, avec une prise en compte des déformations finies, des effets visqueux non linéaires, de l'irréversibilité indépendante du temps et de l'anisotropie. Une mise en œuvre de cette modélisation a été effectuée dans un code d'Eléments Finis, afin de produire un outil opérationnel pour le calcul des voiles. L'approche théorique proposée a été validée grâce à une étude expérimentale détaillée, qui a été réalisée sur le Dacron SF HTP Plus. Ainsi, nous avons réalisé sur ce matériau différents essais de tractions monotones et de tractions ondulées, contrôlés en déformation et en force. Certains de ces essais comportent des séquences de relaxation. Ces essais ont été réalisés dans les axes du matériau, dans le sens chaîne ou dans le sens trame, ainsi qu'en hors axes avec des orientations par rapport à la direction chaîne allant de 5° à 45°. Des résultats expérimentaux complémentaires ont également été obtenus sur une toile laminée en Kevlar X15 et sur un Dacron SF HTM simple. Enfin, une simulation de l'essai de traction biaxiale a été réalisée et a permis d'étudier l'homogénéité des champs de contrainte et de déformation de trois formes d'éprouvette différentes. / This work deals with theoretical, experimental and numerical studies of the mechanical behavior of woven materials and laminated fabrics, made with synthetic fibers, for the manufacture of sails, such as polyester or Kevlar. An original theoretical approach was proposed, it allows taking into account the specific behavior of yarns, of coating and their interactions. The resulting modeling allows describing the behavior of woven materials and laminated fabrics, in the case of complex cyclic biaxial loadings, taking into account finite deformations, nonlinear viscous effects, time-independent irreversibility and anisotropy. The implementation of this modeling was performed in a finite element code, in order to produce an operational tool for the design and calculation of sails. The proposed theoretical approach has been validated through a detailed experimental study, which was conducted on material “Dacron SF HTP Plus”. Thus, we performed various monotonous and cyclic tensile tests, which were strain or load-controlled. Some of these tests include relaxation sequences. These tests were conducted in the axes of the material, in the warp and weft directions, as well as off-axis or bias orientations, from 5 ° to 45 ° with respect to the warp direction. Further experimental results were also obtained on a laminated “Kevlar X15” and a woven “Dacron SF HTM simple” fabrics. Finally, numerical simulations of the biaxial tensile test were performed and were used for studying homogeneity of the stress and the strain fields in the cases of three different contours of biaxial-tensile samples.

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