High resolution numerical and experimental studies of fatigue cracks

Abstract High resolution experimental measurements of near-tip fatigue crack parameters are directly compared with independent high resolution elastic-plastic finite element simulations of growing fatigue cracks. Special attention is given to active crack tip strain fields, crack opening displacements, and crack closure behavior. Proper normalizations are identified to compensate for different material properties, crack geometries, and applied stress levels. Numerical and experimental results are shown to be qualitatively and often quantitatively consistent with respect to observed experimental scatter. The behavior of long cracks under low applied stress levels is compared with the behavior of short cracks under high applied stress levels. Fatigue cracks are compared with elastic and elastic-plastic stationary cracks.