Dugdale crack closure analysis of fatigue cracks under constant amplitude loading

Abstract Fatigue fracture mechanics which means structural analysis including crack propagation and crack closure in conjunction with a local failure criterion provides detailed insight into mechanisms of cyclic loaded crack sheets. Using the Dugdale method and rigid-perfectly plastic strip material law the infinite sheet with colinear cracks was parametrically investigated in respect of: SSY limits, crack closure occurrence, formation of contact stresses and displacements, influences of material parameters, R- ratio and maximum load on effective stress ratio. Rationales for the load ratio, mean load and maximum load dependence and the form of da/dN- curves are given based on crack closure analysis.