How to reduce the duration of multiaxial fatigue tests under proportional service loadings

Abstract

is an open access repository that collects the work of Arts et Métiers ParisTech researchers and makes it freely available over the web where possible. AbstractThis paper deals with a technique to transform a multiaxial stress and strain-time sequence (in service recorded) in a simplified sequence. This simplified sequence is shorter than the original one and equivalent in terms of damage and lifetime: the number of simplified sequences to crack initiation is equal to the number of original sequences. The proposal is based on an energy threshold, below which no micro-crack can initiate or grow in the material. This technique was validated with real loading sequences recorded by strain gauges pasted on a car suspension arm. Fatigue tests were carried out on smooth specimens made of spheroidal graphite cast iron loaded in bending, in torsion and in combined bending and torsion. Experimental fatigue lives under the original sequence and under the simplified one are in very good correlation. Fatigue test duration is reduced up to a factor of 10 for the severe stress-strain sequences tested in this study.

Fatigue curves of a low carbon steel obtained from vibration experiments with an electrodynamic shaker

“…A Wöhler-type curve (ε a -N f ) can be drawn from these failure criteria. The failure criterion is a rather arbitrary choice because of the difficulties to define experimentally the crack initiation [17,18].…”

Fatigue life prediction of low‐alloy steel samples undergoing uniaxial random block loading histories based on different energy‐based damage descriptions

“…Calculated values of Δσ n , Δε n , Δτ max and Δγ max 2 are employed to assess damage in each peak-valley event by VF approach and summed up over entire block history through Eq. (7).…”

“…To assess overall fatigue damage in parts and structures experiencing random block histories, several damage approaches have been developed in literature . Earlier developed stress‐based approaches evaluated fatigue damage response of materials dominantly in high‐cycle fatigue (HCF) regime and strain‐based models promisingly assessed damage of components in low‐cycle fatigue (LCF) region.…”

“…To assess overall fatigue damage in parts and structures experiencing random block histories, several damage approaches have been developed in literature. [1][2][3][4][5][6][7][8][9][10][11][12][13] Earlier developed stress-based approaches [14][15][16] evaluated fatigue damage response of materials dominantly in high-cycle fatigue (HCF) regime and strain-based models [17][18][19] promisingly assessed damage of components in low-cycle fatigue (LCF) region. Fatigue damage of components under variable amplitude loading conditions has been performed on the basis of energy-based damage approaches by several researchers.…”

Determination of fragments of multiaxial service loading strongly influencing the fatigue of machine components

“…Thus, many standardized loading histories are proposed for application at the test stands [1][2][3]. They are usually obtained by numerical processing of the registered service histories, where the amplitude distribution is changed [3][4][5]. In consequence of the changes, the compressed loading history is required to generate much greater damages in the material at the same time but the general characteristic of the loading should be kept.…”