Modeling the Rocking and Sliding of Free-Standing Objects Using Rigid Body Dynamics

A rigid body dynamics algorithm is presented in this paper to simulate the interaction between two rigid bodies, a free-standing rigid object, and a pedestal that has infinite mass, in the presence of static and kinetic friction forces. Earlier algorithms led to different solutions for the contact forces when parameters external to problem description, such as the ordering of contact points, are changed. This paper addresses the issue of selecting an appropriate solution for the contact forces and impulses from the infinite set of solutions by picking the solution that is closest to the previous state of the rigid body. The capability of this algorithm in simulating pure rocking, pure sliding, and coupled rocking-sliding response modes of a rectangular block is validated using analytical/semianalytical results. This validated algorithm is later used to identify the various response modes of a rectangular block, which is given an initial tilt and then released.