Predicting progressive delamination of stiffened fibre-composite panel and repaired sandwich panel by cecohesion models

An approach employing decohesive models with mixed damaged scale and using total fracture energy was developed to simulate the delamination process of a stiffened fibre-composite panel and a repaired composite sandwich panel. Two decohesive material models – a bilinear interfacial decohesive function and the other a cubic polynomial interfacial decohesive function – were developed by using total fracture energy Gc, and based on using interface elements. In comparison with traditional numerical methods in fracture mechanics, this approach automatically predicts the failure load, crack path and the residual stiffness in the fracture process. Applications in this article are delamination analysis of a stiffened fibre-composite panel under four-point bending conditions and a repaired composite sandwich panel under four-point bending test. Comparisons between modeling predictions and experimental observations show that these decohesive models perform well. This article compares the problem of numerical convergent failure between two decohesive material models.