This book serves as a core text for university curricula in solid body mechanics and, at the same time, examines the main achievements of state of the art research in the mechanics of elastic and non-elastic materials. This latter goal of the book is achieved through rich bibliographic references, many from the authors' own work. authors. Distinct from similar texts, there are no claims in this volume to a single universal theory of plasticity. However, solutions are given to some new problems and to the construction of models useful both in pedagogic terms for students and practical terms for professional design engineers. Examples include the authors' decisions about the Brazilian test, stability of rock exposure, and pile foundations. Designed for both upper-level university students and specialists in the mechanics of deformable hard body, the material in this book serves as a source for numerous topics of course and diploma concentration.