Mechanical Behavior of Solids

This chapter describes the mechanical behavior of initially crack-free solids under different loading conditions for determining their mechanical properties, which are important in designing structural components with suitable shapes and dimensional limitations. Thus, the determination of a load-bearing capacity of a material under tension, bending, compressive, torsion, or a combination of mechanical forces is critical in order to assure the integrity of a structural component. Extensive details on mechanical strength and crystallography are coupled in order to characterize the atomic mechanisms of mechanical deformation, specifically, under quasi-static and fatigue loading conditions. In essence, the mechanical behavior of crack-free solids is mainly assessed through the conventional engineering stress-strain diagrams (curves) under quasi-static and fatigue loading. Regarding elastic mechanical deformation, a solid material obeys Hooke’s law at a macroscale, and it recovers its original dimensions upon unloading. Conversely, plastic deformation leads to an irreversible atomic process since the solid material experiences a plastic behavior related to a permanent change of shape. Therefore, plastic deformation induces the formation of defects, such as dislocations, and alters the stress-strain relationship to an extent.