Microscopic measurements of planar viscoelastic body eccentric impacts on a convex corner

This paper presents the effects of the target edge shape on eccentric impact motions, which were experimentally investigated by concurrently measuring the microscopic deformation of the target edge around a contact point and the global trajectory. This study is important for understanding the impact motions that occur between viscoelastic deformable polygonal objects with friction. The materials used in this experiment were four types of resin and one metal; four convex shapes and one circular shape were used for the impacted target plate. Interestingly, anomalous trajectories of the impact plate that varied with the target edge shape were found beyond the regime of rigid body dynamics, and were strongly dependent on the tangential deformation of the edge. In addition, it was found that the tangential deformation amount had a correlation with the bounce-off angle of the impact body for all materials used. That is, the target edge had a weaker tangential stiffness with sharpening of the edge shape, and thus, remarkably, absorbed the tangential impact energy as strain energy, due to a tangential deformation of the edge. Consequently, the bounce-off angle of the elastic body became smaller than that generally expected from rigid body dynamics, and sometimes even became negative because the direction of the contact force is significantly changed with increase in the tangential deformation of the edge.