Analysis of the Numerical and Geometrical Parameters Influencing the Simulation of Mode I and Mode II Delamination Growt
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Analysis of the Numerical and Geometrical Parameters Influencing the Simulation of Mode I and Mode II Delamination Growth in Unidirectional and Textile Composites S. Jacques & I. De Baere & W. Van Paepegem
# Springer Science+Business Media Dordrecht 2014
Abstract The reliability of composite structures depends, among other damage mechanisms, on their ability to withstand delaminations. In order to have a better understanding of the cohesive zone method technique for delamination simulations, a complete analysis of the multiple parameters influencing the results is necessary. In this paper the work is concentrated on the cohesive zone method using cohesive elements. First a summary of the theory of the cohesive zone method is given. A numerical investigation on the multiple parameters influencing the numerical simulation of the mode I and mode II delamination tests has been performed. The parameters such as the stabilization method, the output frequency, the friction and the computational efficiency have been taken into account. The results will be compared to an analytical solution obtained by linear elastic fracture mechanics. Additionally the numerical simulation results will be compared to the experimental results of a glass-fibre reinforced composite material for the mode I Double Cantilever Beam (DCB) and to a carbon fibre 5harness satin weave reinforced polyphenylene sulphide composite for the mode I DCB and mode II End Notched Flexure (ENF). Keywords Composites . Critical strain energy release rate . Double cantilever beam (DCB) . End notched flexure (ENF) . Failure mode . Delamination
1 Introduction Delamination is one of the most difficult and common types of damage in laminated composite structures due to the relatively weak interlaminar strengths. Delamination starts generally at geometrical discontinuities, such as laminate free edges and cut-outs. This is so because the state of stress close to a free edge in a laminate is three-dimensional, with nonzero interlaminar stresses, which grow without bound due to a singularity in the stress field at the intersection of the free-edge and the interface. Delaminations may arise in a composite under various S. Jacques (*) : I. De Baere : W. Van Paepegem Department of Materials Science and Engineering, Ghent University, Technologiepark-Zwijnaarde 903, 9052 Zwijnaarde, Belgium e-mail: [email protected]
Appl Compos Mater
circumstances, e.g. when subject to transverse concentrated loads such as low/high velocity impacts arising from a falling mass. The delamination can then propagate due to the loads on the structure such as dynamic loading. Finally the behaviour of the entire structure changes and in most cases a failure is unavoidable. Since decades, methods based on fracture mechanics have been used to model delamination problems. These methods rely on the assumption of an initial existing crack or void and cannot be applied directly without it. In many papers stress based methods are used in order to predict the delamination initiation and this prec
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