The free-edge effect around holes in composite laminates has recieved less attention than the straight free-edge problem. Mathematical analysis of free-edge stresses around holes have mostly been numerical. The present work develops a simple approximate solution of the hole problem which allows for low cost computation. The method assumes that only the deviations of the ply stresses from the homogeneous plate solution of in-plane stresses around holes contribute to the interlaminar effects. It is then possible to use an equilibrium argument to calculate the interlaminar stresses at the hole boundary. The results obtained show good agreement with numerical results from the literature for a wide range of laminates, predicting the general shapes and signs of interlaminar stress' distributions reasonably well. Experimental observations of delamination found in the literature also agree with the present results. An experimental study of the damage development around holes under quasi-static loading for a number of different laminates is reported. The delamination observed at the hole boundaries are found to be in good qualitative agreement A simple semi-quantitative correlation between these results and a stress combination function of the three interlaminar stress components is also derived. The problems associated with the development of reliable methods of delamination prediction are also discussed. / Applied Science, Faculty of / Mining Engineering, Keevil Institute of / Graduate

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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.

Thesis (M.S.)--Oregon State University, 1980. / Typescript (photocopy). Includes bibliographical references. Also available on the World Wide Web.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 269-276). Also available via the Internet.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1991. / Vita. Abstract. Includes bibliographical references (leaves 182-191). Also available via the Internet.

Thesis (M.S. in Ch. E.)--School of Chemical Engineering, Georgia Institute of Technology, 2004. Directed by Paul A. Kohl. / Includes bibliographical references (leaves 88-91).

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).

Thesis (MTech (Mechanical Engineering))--Peninsula Technikon, 1998. / Word processed copy. Summary in English. Includes bibliographical references (leaves 95-96). Also available online.