Biaxial stress effects on estimating J under combined mechanical and thermal stresses

In this paper, the applicability to bi-axial stress states of a simple approximation proposed in our previous work for quantifying the elastic-plastic J under combined primary and secondary stresses is investigated.To produce the bi-axial stress states, circumferential cracked pipes under combined pressure, axial tension (or compression) and thermal stresses are considered. The results suggest that the proposed approximation can be applied to bi-axial stress states, and is slightly more conservative for bi-axial mechanical stresses than for uni-axial ones. The degree of conservatism decreases with increasing strain hardening exponent and with increasing relative magnitude of secondary stress. - Highlights: → A method to estimate J under combined primary and secondary stresses was proposed by the authors. → This paper extends the proposed method to biaxial primary stress states. → We find that the proposed approximation can be applied to bi-axial stress states. → The proposed approximation is slightly more conservative for biaxial stresses than for uniaxial ones. → The degree of conservatism decreases with increasing hardening exponent and relative magnitude of secondary stress.