Prediction of the dent depth of composite laminates subjected to quasi-static indentation

A method was developed to predict numerically the dent depth of composite laminates subjected to quasi-static indentation. A progressive damage analysis was conducted for composite laminates under quasi-static transverse compressive loading by using a strain based Hashin and Yeh failure criteria as well as the FEM, and a series of degraded elastic constants of the damaged zone were drawn from the numerical results. The effective elastic constants of the damaged zone of the laminates were evaluated according to Sun's explicit expression. Finally, the dent depth vs. indentation force curve was predicted based on Turner's contact theory. The numerical results indicate that the dent initiation is induced by the matrix cracking and delamination, and the transition to rapid increase in dent depth is due to the fiber breakages. The numerical results agree well with the test data for the delamination onset load, the maximum contact force and the corresponding dent depth.