Comparison of analytical methods for the consideration of thermal stresses in the engineering failure assessment

This paper focuses on a comparison of different analytical methods for engineering failure assessment of components subjected to high thermal loading. The primary goal is to validate the analysis tools available within the FAD methodology and thus reduce the conservatism of the analytical assessment. Two well-known approaches based on the rho and V factors, which have been established within the R6 code for taking into account the interaction of the primary and secondary stresses, are considered along with a recently developed V-g, procedure. The analytical methods are validated on examples of two-dimensional crack geometries by varying the crack size, material strain hardening, and the ratio of the primary to secondary stresses. The accuracy of the analytical methods is judged by comparing the estimated elastic-plastic crack driving force with results of direct finite-element calculations. The traditional FAD approach incorporating the rho and V factors is concluded to considerably overestimate the crack driving force, whereas the V-g, method is shown to yield most accurate predictions.