Dynamic contact responses of laminated composite plates according to the impactor's shapes

The dynamic contact behaviors of laminated composite I,lates by a rigid elliptic impactor are discussed. To impose the dynamic contact conditions, the simple laws like the modified Hertz contact law have been used in the early works, but these laws cannot account for a stacking sequence, span or thickness of the laminate, impactor's shape and friction when simulating the dynamic contact behaviors. However, due to the competitive development of cheap powerful microprocessors, the previously prohibitive computing algorithm can be implemented even by the desktop workstations. in this paper, a formulation which can describe the dynamic contact behaviors of composite laminates, precisely, is introduced. A successive iteration method is used for nonlinear analysis and the Newmark method is used for time integration. An algorithm to determine the equilibrium position of a rigid impactor and a composite laminate at each time step is proposed. The effects of the impactor's shape on the quasi-static contact behaviors of isotropic and composite plates are considered. The imp set responses of composite laminates due to transverse impact are also presented according to the shape of the impactor. It is concluded, from the computed results of static indentation, that the higher contact force is obtained when the blunter indentor is used, and from the dynamic impact simulation, maximum impact force is elevated and the impact duration is elongated when the shape of impactor is blunter. (C) 1997 Elsevier Science Ltd.