Multiaxial notch fatigue life prediction based on pseudo stress correction and finite element analysis under variable amplitude loading

Abstract

A new computational methodology is proposed for fatigue life prediction of notched components subjected to variable amplitude multiaxial loading. In the proposed methodology, an estimation method of non‐proportionality factor (F) proposed by authors in the case of constant amplitude multiaxial loading is extended and applied to variable amplitude multiaxial loading by using Wang‐Brown's reversal counting approach. The pseudo stress correction method integrated with linear elastic finite element analysis is utilized to calculate the local elastic‐plastic stress and strain responses at the notch root. For whole local strain history, the plane with weight‐averaged maximum shear strain range is defined as the critical plane in this study. Based on the defined critical plane, a multiaxial fatigue damage model combined with Miner's linear cumulative damage law is used to predict fatigue life. The experimentally obtained fatigue data for 7050‐T7451 aluminium alloy notched shaft specimens under constant and variable amplitude multiaxial loadings are used to verify the proposed methodology and equivalent strain‐based methodology. The results show that the proposed methodology is superior to equivalent strain‐based methodology.

Multiaxial notch fatigue life prediction based on the dominated loading control mode under variable amplitude loading

“…Furthermore, in the light of the statistical research of experimental results, the initiation lifetime of fatigue crack is approximately 33.3% of the total fatigue lifetime for investigated GH4169 alloy notched shaft specimens, 33 and it is 40.0% for notched components made of 7050-T7451 aluminium alloy. 34 In the current study, for the assigned two types of notched shaft components experiencing constant amplitude multiaxial loading, comparison of predicted fatigue lifetimes and experimental results is shown in Figure 10A. As depicted in Figure 10A, the predictive fatigue lifetimes correlate well with experimentally observed fatigue lifetimes, and 83.3% of predicted fatigue lifetime results are inside the factor of three lines.…”

“…They are GH4169 nickel-based superalloy 33 and 7050-T7451 aluminium alloy. 34 For the investigated two materials, the monotonic and cyclic mechanical properties, and fatigue properties are depicted in Tables 1 and 2, respectively. The dimensions and configurations for the assigned two categories of notched shaft components are exhibited in Figure 5A,B.…”

“…For the selected two kinds of materials, the details of established FE models, cyclic fatigue experiments and fatigue test results are able to be discovered within other studies. 33,34 It should be noted that the total fatigue lifetime consists of fatigue crack initiation life and fatigue crack propagation life. 33 The initiation lifetime of fatigue crack for notched component is affected by local stress and strain states at the notch area.…”

New strain energy-based critical plane approach for multiaxial fatigue life prediction

“…Using experimental data of TC4, GH4169 and Al 7050-T7451 alloys, [32][33][34] the proposed model as well as other four models is assessed and verified. In particular, for smooth thin-walled tube specimens of Al 7050-T7451 alloy, the outer diameter of standard distance is 12.5 mm with the inner diameter 10.5 mm and the length 25 mm.…”

Notch fatigue life prediction considering nonproportionality of local loading path under multiaxial cyclic loading

“…Three different types of fully reversed strain-controlled multiaxial fatigue experiments were conducted with triangle waveform, and the investigated loading paths are shown schematically in Figure 11A,D,E. 20 The details of cyclic fatigue experiments, experimental results, and established FE models for the investigated two materials can be found in Sun and Shang 20 and Tao et al 22 In this work, the presented methodology is used to estimate the fatigue crack initiation lives of investigated notched specimens. Comparisons of predicted fatigue lives with experimental results for investigated two kinds of notched shaft specimens subjected to multiaxial constant amplitude loading are depicted in Figure 14A.…”