Complementarity Formulations and Existence of Solutions of Dynamic Multi-Rigid-Body Contact Problems with Coulomb Friction 2 J.S. Pang J.C. Trinkle Mathematical Programming, to appear 1996 MPS http://www.cs.tamu.edu/faculty/trink/Papers/PT_math_prog.ps.Z In this paper, we study the problem of predicting the acceleration of a set of rigid, 3-dimensional bodies in contact with Coulomb friction. The nonlinearity of Coulomb's law leads to a nonlinear complementarity formulation of the system model. This model is used in conjunction with the theory of quasi-variational inequalities to prove for the first time that multi-rigid-body systems with all contacts rolling always has a solution under a feasibility-type condition. The analysis of the more general problem with sliding and rolling contacts presents difficulties that motivate our consideration of a relaxed friction law. The corresponding complementarity formulations of the multi-rigid-body contact problem are derived and existence of solutions of these models is established. Dedication: It gives us great pleasure to dedicate this paper to Professor Richard W. Cottle for his sixtieth birthday on 29 June 1994. Professor Cottle is the founder of the linear complementarity problem. This paper is motivated by an engineering application; like many such applications, complementarity plays a central role in the problem formulation, analysis, and solution. We are indebted to Professor Cottle for the fundamental contributions he has made in this field, for his constant encouragement, advice, and fruitful collaboration over many years. Without his help and guidance, this work would not have been possible.