Crack growth under thermo-mechanical and temperature gradient loads

Abstract

The objective of this work is to examine the utility of so-called modified path-independent integrals, referred to as ''integral parameters'' in this paper, for the prediction of crack growth at elevated temperatures where the crack tip deformation involves plasticity of a large scale. In particular, this paper is concerned with the application of Blackburn's integral J* and Kishimoto ct cll.'s integral (J) over cap to thermo-mechanical fatigue loading and temperature gradient loading. Elastic-plastic finite element ana lyses are performed to simulate crack propagation, and the integral parameters are computed by post-processing the results. Numerical results show that these parameters are indeed path-independent for deformation conditions under investigation. While the isothermal results of previous studies yielded satisfactory correlations between the crack growth rates and these parameters, the quality of correlation for more complex loading conditions investigated here is found to be not always as good as the isothermal cases. However, the overall performance indicates that these parameters are worth investigating further. (C) 1997 Elsevier Science Ltd.