A three-dimensional strain energy density factor theory of crack propagation

Abstract

It is common knowledge that a material will fail under applied load either by separation or segmentation. This process may occur suddenly, or over a long time interval, depending on the temperature, rate of loading, and other variables present. A material that breaks after it has deformed appreciably may have lost its structural usefulness long before it actually separates. In this case, the initiation of yielding or plastic flow may represent failure, and a criterion of yielding such as maximum shear stress or maximum distortional energy may be used. When a material breaks with very little deformation the separation process usually takes place suddenly, and is known as brittle fracture. For materials under uniaxial loading, such as tensile specimens, the maximum principal stress has customarily been used in a brittle failure criterion.