Prediction of low-velocity impact dent for composite laminates based on an anisotropic elastoplastic damage model

In this paper, a three-dimensional finite element (FE) model based on an anisotropic elastoplastic damage model is established to simulate the impact dent of composite laminates subjected to low velocity impact (LVI) by implementing a user-defined subroutine VUMAT in Abaqus/Explicit. To validate the FE model, numerical results are compared with the experimental data in terms of impact dent depth, contact force-time response, and projected delamination shape. The simulation shows that considering tension-compression asymmetry in the elastoplastic constitutive relation has a significant influence on the prediction of dent depth. Besides, it is found that before the knee point, the formation of the impact dent is mainly related to matrix plasticity and damage; while after the knee point, the significant increase of dent depth is caused by fiber breakage on the impact side. The increase of bending stiffness for thicker laminates can decrease the overall deflection, which leads to less fiber breakage and less visible dent.