Linear Elastic Fracture Mechanics and Its Application to Fatigue

This paper summarizes the major aspects of linear elastic fracture mechanics (LEFM) as a quantitative design criterion against brittle fracture. It describes the extension of LEFM to subcritical crack growth under fatigue conditions. To apply this design criterion, however, the engineer must accept the notion that his structure or component does contain flaws or cracks. Fatigue design using LEFM thus assumes preexisting flaws or cracks; hence, fatigue life is based on subcritical crack growth followed by final fracture. Subcritical crack growth under both constant amplitude and variable amplitude loading is considered along with peak tensile or compressive overloads.