Abstract
A new simple analytical approach for predicting all possible damage modes of Uni-Directional (UD) hybrid composites and their stress–strain response in tensile loading is proposed. To do so, the required stress level for the damage modes (fragmentation, delamination and final failure) are assessed separately. The damage process of the UD hybrid can then be predicted based on the order of the required stress for each damage mode. Using the developed analytical method, a new series of standard-thickness glass/thin-ply carbon hybrid composites was tested and a very good pseudo-ductile tensile response with 1.0% pseudo-ductile strain and no load drop until final failure was achieved. The yield stress value for the best tested layup was more than 1130MPa. The proposed analytical method is simple, very fast to run and it gives accurate results that can be used for designing thin-ply UD hybrid laminates with the desired tensile response and for conducting further parametric studies.
Highlights
Fibrous composites are strong and have a good potential for structural applications but they suffer from lack of ductility
The aim of this paper is to propose a new analytical modelling approach by which, all possible UD hybrid damage modes are taken into account
A new analytical approach for predicting the damage development in UD hybrid composites has been presented which is able to predict all possible combinations of damage modes in UD hybrids, making it possible to tailor the optimum desired response
Summary
Fibrous composites are strong and have a good potential for structural applications but they suffer from lack of ductility. The model proposed by Aveston, Cooper, and Kelly [3,4] (Fig. 1) showed the effect of UD hybrid’s constituents proportion for avoiding catastrophic failure, it did not consider delamination. Based on this model, if the proportion of the low to high strain material was lower than a critical value, multiple fractures would happen and if the proportion was higher than a critical value, the hybrid would fail prematurely. More recent studies on application of hybrids to avoid catastrophic failure and increase the pseudo-ductility of composite materials [10,11,12] have reported delamination propagating from the tips of the first crack in the low strain material.
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