Generalized strain energy density-based fatigue indicator parameter

Abstract

In the history of fatigue study, the potentialities of strain energy density (SED) based approaches were extensively discovered; however, there was limited usage in engineering practice, largely due to the lacking of a widely accepted fatigue model and operating instruction. Accordingly, referring to previous studies, a normative form of total strain energy density (TSED) based fatigue life equation with two power function terms is given, together with a standard flow to determine the corresponding SED-related material fatigue parameters, intending to popularize its application in engineering practice. In particular, the positive elastic and plastic SEDs play the dominant role in high and low cycle fatigue domains, respectively. Strain-controlled fatigue tests of virgin Al 7075-T6511 alloy and an in-service puddle iron are conducted to check the effectiveness of the TSED as the fatigue indicator parameter to correlate fatigue life. Results show that the TSED formula works better than the strain-based Coffin–Manson–Basquin equation.