Contact Force Modeling Between Non Convex Objects Using A Nonlinear Damping Model

At Sandia National Laboratories, we are developing the ability to accurately predict motions for arbitrary numbers of bodies of arbitrary shapes experiencing multiple applied forces and intermittent contacts. In particular, we are concerned with the simulation of systems such as part feeders or mobile robots operating in realistic environments. Preliminary investigation of commercial dynamics software packages led us to the conclude that we could use a commercial code to provide everything we needed except for the contact model. We found that ADAMS best fit our needs for a simulation package. To simulate intermittent contacts, we need collision detection software that can efficiently compute the distances between non-convex objects and return the associated witness features. We also require a computationally efficient contact model for rapid simulation of impact, sustained contact under load, and transition to and from contact conditions. This paper provides a technical review of a custom hierarchical distance computation engine developed at Sandia, called the C-Space Toolkit (CSTk). In addition, we will describe an efficient contact model using a non-linear damping term developed at Ohio State. Both the CSTk and the non-linear damper have been incorporated in a simplified two-body testbed code, which is used to investigate how to correctly model the contact using these two utilities. We have incorporated this model into ADAMS SOLVER using the callable function interface. An example that illustrate the capabilities of the 9.02 release of ADAMS with our extensions is provided. { EMBED Word.Picture.6 } Figure { SEQ Figure \* ARABIC }: Multiple Contacts Between a Non-Convex Part and a Table Top