Differential Inclusions in Nonsmooth Mechanical Problems : Shocks and Dry Friction The book is devoted to evolution problems which arise in the dynamics of mechanical systems involving unilateral constraints possibly in the presence of dry friction. Collisions may be the result. In such a context the velocity function cannot be expected to be absolutely continuous so the traditional theory of differential equations or inclusions does not apply. Some effective numerical techniques have been proposed but existence results were missing until now. This book starts filling that gap. At first some typical mathematical tools are introduced such as compactness results in the space of vector functions of bounded variation in time and approximation in the sense of graphs. The sweeping process by a moving convex set in a Hilbert space plays a central role. The latest existence results concerning this process are presented in chapter 2. In chapters 3 and 4 the study of the mechanical problems is undertaken. Connected areas of research are briefly reviewed in chapter 5. Proofs are constructive whenever possible and convergence of algorithms is often considered. The book presupposes only a moderate background in functional analysis