Multiaxial Low Cycle Fatigue Life Evaluation of Different Materials under Non-proportional Loading

Abstract

Components and structures like pressure vessels and high temperature exchangers undergo multiaxial low cycle fatigue (LCF) damage. It has been reported that fatigue lives are reduced accompanying an additional hardening under strain controlled non-proportional loading in which directions of principal stress and strain are changed in a cycle. Developing an appropriate design parameter for multiaxial LCF is required for the reliable design and maintenance of structure components. This study examines the relationship between additional hardening and reduction in fatigue life due to non-proportional loading and its material dependence. By performing the multiaxial LCF tests using different materials, a material constant, α, used in a strain parameter for life evaluation under non-proportional multiaxial LCF is discussed.