Abstract

Vibratory stress relief is a green and efficient aging technology compared with traditional natural stress relief and thermal stress relief. The research aimed to determine whether vibratory stress relief is feasible to improve the fatigue life of aluminum alloy 7075-T651 or not. Under the same resonance frequency, analyses and comparisons of the residual stress distributions before and after vibratory stress relief are presented with X-ray method. Experimental results indicate that vibratory stress relief is effective in reducing and equilibrating residual stresses. Through uniaxial tension–compression fatigue tests, we obtained the S–N curves for specimens under states of original and varying exciting forces. Findings led to the conclusion that vibratory stress relief can improve the fatigue life of aluminum alloy 7075-T651 when dynamic stress does not exceed 8% of the yield strength.

Highlights

  • With the rapid development of the modern aircraft industry comes a high demand for aluminum alloys with greater fatigue life

  • Vibratory stress relief (VSR) technology is a green and efficient aging technology compared with the traditional natural stress relief (NSR) and thermal stress relief (TSR)

  • The results indicated that the fatigue life of welds dropped 43% after TSR and that the fatigue life of welds increased 17%– 30% after VSR

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Summary

Introduction

With the rapid development of the modern aircraft industry comes a high demand for aluminum alloys with greater fatigue life. Advances in Mechanical Engineering limited influence on the macroscopic residual stress state, but found that VSR treatment increased damage to the microstructure that caused the decreased fatigue life of ultra high-strength steel. Wozney and Crawmer[7] investigated the mechanism of VSR and its application to large-scale welded fabrications by experimental method They believed that the cyclic hardening characteristics of the test material could be cited as a possible factor affecting the degree of stress relief. The relationship between changes in the residual stress and the VSR process under first-order resonance frequency, as well as the varying exciting forces on aluminum alloy specimens, was studied in regard to the effect of VSR on fatigue life by experimental methods. The number of specimens used by each cyclic stress level was five

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