Experimental Evaluation of Fatigue Parameters Using Constant K Fracture Specimens

Abstract

We explore the use of constant K fracture specimens for experimental determination of fatigue properties of aluminum alloys. The shape of the contoured portions of the fracture specimens (required to keep the mode I stress intensity factor constant during crack propagation under constant cyclic loading) was obtained by a combined finite element-least squares minimization procedure. After conducting the experiments, the crack growth rate versus ΔK data was observed to exhibit significantly less scatter than fatigue data for the same material taken from the literature. In addition, the experimental procedure is much simpler to carry out than traditional closed-loop computer controlled procedures.