Thickness effect on the contact behavior of a composite laminate indented by a rigid sphere

A modified Hertz contact law is proposed for the contact problem of a laminated plate indented by a rigid sphere, which involves the effects of the thickness, in-plane dimensions and boundary conditions of the plate. The model shows that the deflection difference between the center and the edge of the contact area is a key factor dominating the effects of these variables on the force-indentation response. The modified contact law is assumed to follow the same mathematical formulation as the Hertz law. However, the contact stiffness is no longer constant but varies as a function of the contact force due to the thickness effect. The predictions of the force-indentation response show improved agreement over early work by Yang and Sun. Over the present analysis range, the thickness effect may be negligible if the plate thickness is greater than 2 mm. On the other hand, the thickness has a more significant effect on the force-indentation response if the plate thickness is less than 2 turn. Moreover, the in-plane dimensions and the boundary conditions of the plate show little influence on the force-indentation response within the present scope of analysis. (c) 2007 Elsevier Ltd. All rights reserved.