Determination of multiaxial stress rupture criteria for creeping materials: A critical analysis of different approaches

Materials in engineering applications are rarely uniaxially-loaded. In reality, failures under multiaxial loading has been widely observed in engineering structures. The life prediction of a component under multiaxial stresses has long been a challenging issue, particularly for high temperature applications. To distinguish the mode of failure ranging from a maximum principal stress intergranular damage to von Mises effective stress rupture mode a multiaxial stress rupture criterion (MSRC) was originally proposed by Sdobyrev and then Hayhurst and Leckie (SHL MSRC). A multiaxial-factor, alpha, was developed as a result which was intended to be a material constant and differentiates the bias of the MSRC between maxi-mum principal stress and effective stress. The success of the SHL MSRC relies on accurately calibrating the value of alpha to quantify the multiaxial response of the material/geometry combination. To find a more suitable approach for determining MSRC, the applicability of different methods are evaluated. Given that the resulting analysis of the various approaches can be affected by the creep failure mechanism, principles in the determination of MSRC with and without using continuum damage mechanics approaches are recommended. The viability of uniaxial material parameters in correlating with alpha through the analysis of available data in literature is also presented. It is found that the increase of the uniaxial creep dam-age tolerance parameter lambda is accompanied by the decrease of the alpha-value, which implies that the creep ductility plays an important role in affecting the multiaxial rupture behavior of materials. (C) 2022 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.

Automated summary

This article discusses the failure behavior and life prediction of engineering materials under multiaxial loading. A multiaxial stress rupture criterion (MSRC) is proposed to distinguish different failure modes, and a multiaxial factor alpha is developed to quantify the multiaxial response of material/geometry combinations. Different methods for determining MSRC are evaluated, and the use of continuum damage mechanics approaches in determining MSRC is recommended, considering the influence of creep failure mechanisms. The correlation between uniaxial material parameters and alpha is also analyzed. The study finds that the increase of uniaxial creep ductility parameter lambda is accompanied by a decrease in alpha, indicating the role of creep ductility in the multiaxial rupture behavior of materials.