Chapter 1 - Introduction: Materials under stress

Abstract

This chapter describes the state of the art in the prediction of material failure as articulated in national standards and specifications, and as used in practice in engineering companies. The chapter reviews the background material, symbols, and terminology related to materials under stress. A fundamental way to obtain information about the mechanical properties of a material is to record its stress–strain curve, usually by applying a gradually increasing tensile strain to a specimen of constant cross section. The chapter focuses on the deformation and failure of materials under stress, but emphasizes upon brittle fracture and fatigue including ductile fracture and certain tribological failure modes such as fretting fatigue. Material failure can be determined with precision only in two rather special cases. The first is simple tension, as described by the stress–strain curve: and the second is the propagation of pre-existing cracks, as described by linear elastic fracture mechanics (LEFM).. The use of computer-based methods such as finite element analysis (FEA) is also discussed. The chapter also highlights the use of traditional fracture mechanics and solid mechanics in failure prediction.