Abstract
In cross-ply laminates, the shape of delamination areas, which form due to low velocity impact, have two subtle features, which have been observed consistently in numerous experiments. Those are the pointed delamination tips and the intact zone between the lobes of delamination. However, there have not been any account available in the literature how they can be consistently captured through numerical modelling, and hence these features in published modelling results were often absent. It is the objective of this paper to identify the underlying modelling considerations so that these features can be captured with confidence. A key and unique reason has been identified in each case. Namely, inclusion of intra-laminar damage allows to reproduce the pointed delamination tips, while the gap between the lobes of delamination can be captured by models with sufficiently refined mesh, where friction between the laminas is taken into account. The capability of capturing these subtle features helps to raise the level of fidelity on the simulation of delamination due to impact.
Highlights
Delamination in laminated composites caused by low speed lateral impact has been subjected to countless investigations from various perspectives [1], to such an extent that standards [2] have been drawn, as the problem has been considered as one of the key aspects in material selection, in particular, for aerospace applications.Cross-ply laminates are one of the simplest types of laminates, which is not of much practical significances in terms of their engineering applications
Based on the analysis presented here, it can be concluded that the intra-laminar damage, i.e. the transverse matrix cracking in the 0 lamina distal to the impactor is the reason for the experimental observation of the pointed delamination tips
This study indicates that the quantitative predictions of the size of the intact zone would require more accurate way of simulating the Hertzian contact between the impactor and the laminate
Summary
Delamination in laminated composites caused by low speed lateral impact has been subjected to countless investigations from various perspectives [1], to such an extent that standards [2] have been drawn, as the problem has been considered as one of the key aspects in material selection, in particular, for aerospace applications. Sitnikova et al / Composites Science and Technology 149 (2017) 149e158 delamination predictions Another closely associated and even more important issue is the inability to comprehensively explain two subtle features of delamination as will be defined below, which are observed consistently in impact tests of cross ply laminates, but are not captured in many accounts exploring the subject. Such subtle features are not as significant as the delamination area and dimensions in representing the effects of the delamination, the inability to capture them does cast doubts on the fidelity of predictions, even if one has managed to estimate the area and the dimensions reasonably accurately Without capturing such consistently observable features, the authors would find it hard to be content with the existing simulation capability. Through the specific considerations introduced to the model as presented in this paper, these subtle features will be reproduced vividly and reasons responsible for these features will be identified
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