This book deals with the dynamics of mechanical systems in presence of impact and friction. The contributors are an international group of engineers and scientists from industrial and academic institutions of more than 23 countries around the world concerned with the modeling, analysis, measurement and control of nonsmooth mechanical structures. Contact laws lead to mathematical models that are highly nonlinear and nonsmooth or discontinuous. Discontinuous and nonsmooth processes introduce problems with data processing techniques and analytical methods. Thanks to great advances in computer technology and computational analysis, as well as the introduction of new experimental devices such as the atomic-force microscope and the quartz-crystal-microbalance probe, the study of impact and friction — one of the oldest problems in physics, is now in a phase of rapid and exciting development. The growing number of research breakthroughs have promoted the development of new technologies in the description and design of systems with impact and friction models to understand nature, structures, machines, transportation systems, and other processes. A fairly comprehensive picture of these new developments is presented in this book by researchers who are giving up-to-date accounts of the present state of the field in many aspects.The book is essential for introducing readers in mechanical engineering, material science, applied mathematics, aerospace engineering, ocean engineering, biomechanics, and civil engineering to recent developments in nonsmooth mechanics. It is also useful for self-study purposes by professionals and practitioners in the field.