A new methodology for computing crack opening values from finite element analyses

Finite element analyses are frequently used to model growing fatigue cracks and the associated plasticity-induced crack closure. A new methodology is presented to calculate crack opening values in planar geometries using the crack surface nodal force distribution under minimum loading as determined from finite element analyses. The calculated crack opening values are compared with values obtained using finite element analysis and more conventional crack opening assessment methodologies, which focus on a single node near the crack tip. The new method eliminates the need to arbitrarily select a single node when defining the opening load or stress.