Prediction of permanent indentation due to impact on laminated composites based on an elasto-plastic model incorporating fiber failure

In this work a method was proposed to predict the permanent indentation due to low-velocity impact on laminated composites, which adopted an anisotropic elasto-plasticity theory. Experimental results showed that fiber failure is a prominent phenomenon and an important reason for the knee point on the dent depth-impact energy curves of composite laminates subjected to low-velocity impact. The finite element model to predict the permanent indentation incorporated fiber failure in the anisotropic elasto-plasticity theory. Delamination was also taken into account in the finite element model using cohesive elements. The permanent indentation numerically predicted agreed well with the experimental results. Composite laminates with different fiber-resin systems were analyzed which showed that the effect of different materials especially different fibers on the permanent indentation can be reflected in the present model. Numerical results showed different ways of energy dissipation which also reflected different damage modes before and after the knee point.