Abstract

The concepts of fracture mechanics, a methodology which characterizes the resistance of a material to crack propagation, are described, beginning with the stresses around the tip of a crack in an elastic material. An alternative approach based on the energy available to grow a crack is also discussed. The complications arising from plastic yielding at the crack tip in real materials are described, together with the testing restrictions required to ensure a valid experimental measurement of fracture toughness. Linear elastic fracture mechanics or elastic-plastic fracture mechanics may be appropriate, depending on the extent of plastic yielding in the test material. The application of fracture mechanics to fatigue crack growth, impact loading, and dynamic crack propagation problems is briefly reviewed. Design considerations for crack stability and lifetime prediction in cyclic loading are also considered.