A comparative evaluation of K sub(op) determination and Delta K sub(eff) estimation methods

Methods for determination of the crack opening stress intensity factor (K sub(op) ) and for estimation of the effective stress intensity factor range ( Delta K sub(eff) ) are evaluated for crack growth test data of aluminum alloys. Three methods of determining K sub(op) , visual measurement, ASTM offset compliance method, and the neural network method proposed by Kang and Song, and three methods of estimating Delta K sub(eff) , conventional, the 2/P10 and 2/PI methods proposed by Donald and Paris, are compared in a quantitative manner by using evaluation criteria. For all K sub(op) determination methods discussed, the 2/PI method of estimating Delta K sub(eff) provides good results. The neural network method of determining K sub(op) provides good correlation of crack growth data. It is recommended to use 2/PI estimation with the neural K sub(op) determination method. The ASTM offset method used in conjunction with 2/PI estimation shows a possibility of successful application. It is desired to improve the ASTM method.