Prediction of Damage Extension in Laminated Structures under Transverse Loads

In this paper, to deal with the complex damage propagations in various composite structures under quasi-static transverse loads, a numerical simulation methodology based on the three-dimensional (3D) finite element method is proposed. In this numerical model, two categories of damage patterns existing in composite structures under transverse loads are tackled independently. First, a stress-based criterion is adopted to deal with the first category, i.e. various in-plane damages, such as fiber breakage, transverse matrix cracking etc. Second, a bi-linear cohesive interface model is employed to deal with the second category, i.e., interface damages, such as delaminations. Also, to remove the numerical instability when using the cohesive model, we propose a simple and useful technique, where the move-limit in the cohesive zone is built up to restrict the displacement increments of nodes in the cohesive zone after the occurring of delaminations. This numerical model is further applied to various composite structures, such as 2D laminated plates and 3D laminated shells under the transverse loads. A lot of information is provided for understanding the propagation mechanisms of various damages in composite structures.