Impact analyses suffer from several practical limitations which limit their application to predict the approximate magnitude of the various phenomena involved. The transient force deformation response of a body subjected to impact can be explained accurately using the stress wave propagation theory. As this approach is complicated, a simpler approach utilizing a quasi-static equilibrium condition can be employed. Nonlinear force-deformation Hertzian relations can be used for the impact analysis. These relations though can not explain the energy dissipation and permanent deformations encountered during the impact. This necessitates independent nonlinear force deformation relations for compression and restitution phases of impact. In this paper; modeling of contact forces during impact on stiff systems (systems which do nor undergo gross deformation but experience only local deformation) has been presented. Experiments were conducted on stiff systems to verify the methodology. A plate which is fixed on a rigid base and clamped completely represents a stiff system. Hence experiments were conducted on Aluminum and Steel plates to simulate impact on stiff systems for the verification of the proposed models. The theoretical results matched well with the experimental results. A nonlinear force deformation model with independent relations for compression and restitution phases was found to be a suitable approach to analyze impact problems.
