Evaluation of Elber's Crack Closure Model as an Explanation of Train Load Sequence Effects on Crack Growth Rates

摘要

Elber's crack closure model is studied in relation to the results of laboratory spectrum crack growth tests on compact tension specimens (CTS) fabricated from rail steel. Comparison of model predictions with test results for crack growth life is effected by means of an analysis of a center cracked panel (CCP) subjected to an equivalent stress spectrum. (The model cannot be directly applied to the CTS because it is numerically unstable when supplied with finite element approximations for the elastic displacement field at the plastic zone boundary.) The trends of the model predictions and test results agree as to the effect of changing cycle order in the spectrum, but the actual effect on crack growth life in the laboratory tests is found to be much stronger than the effect predicted by Elber's model.