FE Modeling of Interacting Indentation, Flexural and Delamination Damage in Lap Joints of Composites

Abstract

Composite lap joints are essential for various applications such as aircraft wings, piping networks, sporting equipment and civil engineering works. The low velocity impact on such joints is a common occurrence in real life situations. The response of these joints under such impacts is quite complex. This involves multiple interacting damage modes that may occur within plies (fiber and matrix damage), at interfaces between plies (delamination) and at the bond interface (joint failure), indentation, flexural and shearing loads caused by impact. These may lead to significant degradation of joint strength without apparent complete failure. Thus it is very important to predict the response and behavior of such joints under impact. Many researchers have dealt with problem of impact damage modeling, however these approaches are either too complex or require material parameter that may not have clear physical meaning. Thus, the objective of the study was to demonstrate a consistent set of methodology for evaluation of damage parameters for built in damage progressive models in ABAQUS and validating the methodology by applying on a lap joint impact problem. The damage model used in a previous study (Choudhry et al. IJIE, 80 (2015)) is improved to include laminate damage in addition to delamination and bond failure. The study follows a continuum damage modeling approach. Different progressive damage models for composite materials that are available in the literature were studied/reviewed by the author. Hashin damage model is one of the built in progressive damage model in ABAQUS. In this study, Hashin damage model is used for modeling laminate failure in this study. The model is implemented using plane stress elements (continuum shell). Mesh convergence and reduction in overall computational cost is an important consideration for such models. This point is discussed extensively in current work. The results of simulations are validated against experimental data of previous study. The study will be helpful for practicing engineers, as it provides them with the consistent and easy to use methodology for evaluating damage parameters for practical impact simulation problem