MECHANICS OF DEFORMABLE BODIES ENGR. JEMUEL N. LOPEZ STRESS & STRAIN Introduction to Mechanics of Materials Introduction The three fundamental areas of engineering mechanics are statics, dynamics, and mechanics of materials. Statics and dynamics are devoted primarily to the study of the external effects upon rigid bodies—that is, bodies for which the change in shape (deformation) can be neglected. Mechanics of materials deals with the internal effects and deformations that are caused by the applied loads. Internal Forces Internal Forces - forces that act on cross sections that are internal to the body itself Stress Stresses on Inclined Plane Stresses on Inclined Plane Stresses on Inclined Plane Working Stress (Allowable Stress) Procedure for Stress Analysis