This book establishes a modern practical approach to mechanical design. It introduces a full set of mechanical design theories and approaches to conduct and complete mechanical design tasks. The book uses Finite-Element Analysis (FEA) as a mechanical engineering tool to calculate stress/strain and then integrate it with failure theory to complete the mechanical design. FEA simulation always evaluates the stress and strain of any component/assembly no matter whether components/assemblies have complicated geometries and/or are under complicated loading conditions.