Multiaxial Fatigue Under Variable Amplitude Loads

Abstract

Multiaxial fatigue under variable amplitude loading is investigated using Kandil et al.’s parameter, rainflow cycle counting on the shear strain history, and the Miner-Palmgren damage rule. Fatigue data are obtained on tubular specimens of S45C steel under proportional and nonproportional tension-torsion loading. The approaches using the maximum shear strain range (Δγmax) plane and the maximum damage (Dmax) plane as the critical plane are investigated. The damage is computed for each reversal or for each cycle. The results show that both Δγmax and Dmax approaches yield acceptable fatigue lives irrespective of the damage computation method. Damage computation for each reversal tends to shift fatigue life toward the nonconservative side for some nonproportional loading. It is concluded that the overall procedure used in this study is viable for multiaxial life prediction under variable amplitude loading for the test material.

Evaluation of Estimation Methods for Shear Fatigue Properties and Correlations with Uniaxial Fatigue Properties for Steels and Titanium Alloys

“…The inhomogeneity of hardness in these specimens in addition to the stress gradient caused by torsional loading result in inconsistencies in correlations between uniaxial and shear fatigue properties. The details of the experiments on the materials used in the data pool can be found in [7,13,[16][17][18][19][20][21][22][23][24][25][26][27][28][29] and monotonic and fatigue properties are presented in Table 1. [7] 206/79 798 234 1400/630 0.449/1.22 -0.107/-0.080 -0.564/-0.564 SF60 [7] 208/79 820 167 978/504 0.187/0.286 -0.082/-0.067 -0.439/-0.417 SFNCM85S [7] 201/80 825 241 1040/533 0.316/0.251 -0.092/-0.071 -0.522/-0.406 SCM435 [7] 210 The materials in bold are tested in this study.…”

The Modified Manson–Coffin Curve Method to estimate fatigue lifetime under complex constant and variable amplitude multiaxial fatigue loading

“…Specimens of S45C [4], 304SS [53], SNCM439 [55], SNCM630 (A) [56] and SNCM630 (B) [55] subjected to short variable amplitude load histories.…”

“…[48], pure titanium [14], titanium BT9 [14], SNCM439 [55], SNCM630 (A) [56] and SNCM630 (B) [55] tested under fully-reversed sequential loading (A=Axial cyclic loading; T=torsional cyclic loading: I=in-phase axial loading and torsion: O=90° out-of-phase axial loading and torsion). : Specimens of S45C [4], 304SS [53], SNCM439 [55], SNCM630 (A) [56] and SNCM630 (B) [55] subjected to short variable amplitude load histories. …”

“…Owing to the high costs associated with fatigue failures, since the beginning of the last century a tremendous effort has been made by the international scientific community to devise appropriate engineering tools suitable for estimating fatigue damage under complex loading paths. If attention is focused on the low/medium-cycle fatigue regime, examination of the state of the art [1][2][3][4][5][6][7] suggests that, so far, this intractable design problem has being addressed mainly by trying to extend the use of wellknown constant amplitude (CA) multiaxial fatigue criteria to those situations involving multiaxial VA load histories. In this context, among the methods which have been employed so far, certainly the SWT parameter [8,9], Brown & Miller's criterion [10,11], and Fatemi & Socie's critical plane approach [12,13] deserve to be mentioned explicitly.…”

Estimation of fatigue lifetime for selected metallic materials under multiaxial variable amplitude loading

“…number of experimental data were selected from the technical literature [19,20] to check the accuracy of the considered procedures in estimating multiaxial fatigue lifetime. The summary of the static and fatigue properties of the investigated materials are reported in Tabs.…”