Application of Life-Dependent Material Parameters to Fatigue Life Prediction under Multiaxial and Non-Zero Mean Loading

Abstract

This study presents the life-dependent material parameters concept as applied to several well-known fatigue models for the purpose of life prediction under multiaxial and non-zero mean loading. The necessity of replacing the fixed material parameters with life-dependent parameters is demonstrated. The aim of the research here is verification of the life-dependent material parameters concept when applied to multiaxial fatigue loading with non-zero mean stress. The verification is performed with new experimental fatigue test results on a 7075-T651 aluminium alloy and S355 steel subjected to multiaxial cyclic bending and torsion loading under stress ratios equal to R = −0.5 and 0.0, respectively. The received results exhibit the significant effect of the non-zero mean value of shear stress on the fatigue life of S355 steel. The prediction of fatigue life was improved when using the life-dependent material parameters compared to the fixed material parameters.

Limited Stress Surface Model for Bending and Torsion Fatigue Loading with the Mean Load Value

“…The previously presented calculation models contain material properties that are constant values. Meanwhile, some research results indicate that the fatigue properties of the material may change with the number of cycles, and it is postulated that this effect should be taken into account in calculation algorithms [14,16,23,24]. Some proposals extend the applicability of the Goodman, Gerber, and other mentioned models in the range of lowcycle fatigue by taking into account the current number of failure cycles in transformation models [25,26].…”

“…It is also pointed out in the literature that the limitation of the dependence of the Goodman and Gerber model is significant at the fatigue limit level. Gasiak and Pawliczek [13] and Kluger et al [14] showed that the parameters of computational models considering the mean value change with the number of cycles. Verification of the computational models for so-called life-dependent material parameters was performed for specimens made of S355 alloy steel [13,14] and 7075-T651 aluminum alloy [14].…”

“…Gasiak and Pawliczek [13] and Kluger et al [14] showed that the parameters of computational models considering the mean value change with the number of cycles. Verification of the computational models for so-called life-dependent material parameters was performed for specimens made of S355 alloy steel [13,14] and 7075-T651 aluminum alloy [14]. Taking these effects into account, a more accurate estimation of the fatigue life of the materials was achieved.…”

Fatigue Prediction of Aluminum Alloys Considering Critical Plane Orientation under Complex Stress States

“…In this case as well, the fatigue strength is estimated [ 20 , 21 ] and crack propagation is observed [ 22 ]. A new proposition for estimating the fatigue strength, based on factoring in the variability in material parameters, was presented in [ 10 , 23 ]. In these works, the models were verified based on the findings from studies on fatigue in aluminium alloys.…”