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Mesh-independent modelling of transverse cracks in laminated composites under quasi-static and impact loading

Kawashita, Luiz F., Bedos, Alexandre and Hallett, Stephen R. 2012. Mesh-independent modelling of transverse cracks in laminated composites under quasi-static and impact loading. Presented at: 10th World Congress on Computational Mechanics, Sao Paulo, Brazil, 8-13 July 2012.

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Fibre-reinforced laminated composites subjected to quasi-static or low-velocity impact loading usually fail due to combinations of three damage mechanisms, namely (i) delamination between plies, (ii) transverse matrix cracking and (iii) fibre failure. In the past decade, variants of the Cohesive Zone Model (CZM) have been implemented and used successfully in the analysis of delamination. Conventional CZM is suitable in this case because delaminations can only occur along well-defined ply interfaces. The analysis of transverse matrix cracks on the other hand is much more complex because the locations are not known a priori. The recent development of the extended finite element method (XFEM) has enabled the treatment of cohesive cracks independently of the mesh definition. However, difficulties still arise in following complex solution paths when multiple cracks are taken into account. The present work focused on the development of a robust algorithm for modelling mesh-independent matrix cracks in explicit time-integration finite element (FE) solutions. This was implemented as a user-defined element subroutine for the commercial software Abaqus/Explicit. Fully-integrated linear hexahedral elements are made capable of representing strong discontinuities via the introduction of additional degrees of freedom. The initiation and propagation of discontinuities is solution-dependent and the resulting crack paths are nearly independent of the mesh definition. The formulation is greatly simplified by the enforcement of rules based on the characteristics of real matrix cracks. The proposed method was employed in the analysis of progressive failure of carbon-epoxy laminates in open-hole tensile tests. For quasi-static loading a global mass scaling strategy was adopted in order to reduce CPU cost. Numerical results are compared with experiments in terms of delamination area, location and length of matrix cracks, and global force-displacement response. The model was also used to investigate open-hole tests under dynamic (impact) loading. It is shown that the proposed method has several advantages over conventional CZM tools for high loading rates. One key advantage is the absence of compliant interfaces within the undamaged material. This eliminates spurious wave reflections which can be observed with conventional CZM methods.

Item Type: Conference or Workshop Item (Paper)
Date Type: Completion
Status: Unpublished
Schools: Engineering
Centre for Advanced Manufacturing Systems At Cardiff (CAMSAC)
Subjects: T Technology > TJ Mechanical engineering and machinery
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Last Modified: 19 Mar 2016 09:11

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