On the assessment of multiaxial fatigue damage under variable amplitude loading

V Anes,L Reis,M De Freitas

doi:10.3221/igf-esis.37.17

V Anes, L Reis + Show 1 more

Open Access

https://doi.org/10.3221/igf-esis.37.17

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Journal: Frattura ed Integrità Strutturale	Publication Date: Jun 13, 2016
Citations: 6	License type: cc-by

Affiliation: University of Lisbon

Abstract

In this work, the performance of the SSF criterion is evaluated under variable amplitude loading conditions. The main objective was to inspect the validity of the hypothesis in which the SSF damage map remains valid for any high strength steel. In order to achieve that, fatigue life correlation of the 1050QT steel and 304L stainless steel was analyzed under multiaxial loading conditions. The loading block considered in the study comprises 360 proportional loading cycles with different stress amplitude ratios and stress levels. Despite being made of proportional branches, this loading block is a non-proportional loading due to its principal directions variation. This feature allows the evaluation of combined loading effects under variable amplitude loading conditions, which makes this loading block suitable to mimic the loading effects usually found in the field. Results show very good agreements, which reinforces the aforementioned hypothesis

Highlights

I n the field, random loadings are the most common type of load that we can find; typical examples can be found in car suspensions, aircraft wings or wind towers
The experimental block results shown in the fourth column were obtained by dividing the number of experimental reversals at failure by 360 (360 proportional loadings found within the FRI loading block), this result shows the number of block repetitions during experiments at each stress level
The present study evaluates the performance of the SSF criterion under variable amplitude loading for two different materials, i.e. the 1050QT steel and the 304L stainless steel

Summary

Introduction

I n the field, random loadings are the most common type of load that we can find; typical examples can be found in car suspensions, aircraft wings or wind towers. The SSF damage map, given by the 5th polynomial function shown in Eq (2) was obtained for the 42CrMo4 material and translates its cyclic behavior under different stress amplitude ratios and stress levels. The mechanical properties of the 304L stainless steel are clearly out of the high strength steels family [9], it is expected a lower performance in the SSF fatigue life correlations for this material.

Results

Conclusion