Low cycle fatigue life prediction of FGH96 alloy based on modified SWT model

To solve the problems that Smith-Watson-Topper (SWT) model does not consider the sensitivity of material to the mean stress and ignores the effect of the mean stress on plastic deformation, we improved the computing method of the Walker exponent γ based on the yield strength and tensile strength, and modified the damage control parameter of the SWT model using the improved Walker exponent. Meanwhile, based on the Manson-Halford (M-H) model, the plastic deformation parameter of the SWT model was modified with the mean stress. Then an Low Cycle Fatigue (LCF) life prediction method for the FGH96 powder metallurgy superalloy was proposed based on the improved SWT model. The improved computing method of the Walker exponent was verified using the experimental calculation values of different materials, and the average relative error of calculation is 10.25%. The experimental data of the FGH96 alloy and other aero-engine materials show that the improved SWT model can provide better prediction than the M-H, SWT and Lv models, with nearly all the predicted results within ±2 times the scatter band. © 2021, Beihang University Aerospace Knowledge Press. All right reserved.