Mode III Fracture in Advanced Engineering Materials

Christou Pennas, Dimitrios (2007) Mode III Fracture in Advanced Engineering Materials. PhD thesis, University of Liverpool.

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Abstract

Delamination is a fundamental failure mode of laminated composites. When laminates are subjected to out-of-plane loading, the resin matrices between the plies often fail, resulting in ply separation or delamination failure. Such loading conditions occur in various ways and depend heavily on the load transfer mo~es in the composite structures. Delamination cracks can be visualised in the fracture mechanics sense to grow, and thus can be characterised in Mode I (opening), Mode II (shear) and Mode III (scissoring or anti-plane shear) and their combinations. __The test techniques for delamination in Mode I and Mode II, as well as mixed Mode IIII, have been well established. However, few workers have investigated the Mode III interlaminar fracture properties of composites, partly because of the experimental difficulties associated with the introduction of pure Mode III loading to the delamination crack. The aim of this study was to investigate the Mode III interlaminar fracture properties of composite materials based on both thermoplastic and thermosetting matrices, adhesive joints and bi-material samples. For this reason, both numerical and experimental methods were used. The Edge Crack Torsion (ECT) test geometry was employed in order to evaluate the Mode III response of the samples studied, as it is commonly accepted that this is the most effective technique for cllaracterising this mode of delamination. The Virtual Crack Closure Integral has also been extensively used to characterise the loading conditions at the crack tip in these samples. Once the quasi-static response of the composites were analysed, dynamic tests were undertaken to investigate the rate-sensitive behaviour of these high-performance materials. Finally, the Mode III geometry was modified to look at possible mixed-mode failure involving Mode II contributions.

Item Type:	Thesis (PhD)
Depositing User:	Symplectic Admin
Date Deposited:	20 Oct 2023 09:25
Last Modified:	20 Oct 2023 09:28
DOI:	10.17638/03174584
Copyright Statement:	Copyright © and Moral Rights for this thesis and any accompanying data (where applicable) are retained by the author and/or other copyright owners. A copy can be downloaded for personal non-commercial research or study, without prior permission or charge
URI:	https://livrepository.liverpool.ac.uk/id/eprint/3174584