Analytical and Numerical Analysis of Fatigue Life Estimation of Shot Peened Spur Gear

Abstract

A spur gear was the most simple, widely used, and efficient type of gear. They were subjected to bending fatigue failure. The bending fatigue failures began at or near the tooth root sur face of the gear. Shot peening was a widely used surface treatment by inducing compressive residual stress in order to extend the fatigue life of the gear tooth root. The aim of this thesis was to analyze the fatigue life of shot peened spur gear for different crack lengths, which de pended on the magnitude and depth of the compressive residual stresses. The analytical and numerical analysis was used to estimate the fatigue life of the single tooth of the spur gear and experimental data, which was from the literature were used to validate with calculated value and numerical results. The finite element package ABAQUS 6.20 was used for simulating the shot peening process and crack modeling process, considering the target to be deformable and the shot to be rigid. The maximum compressive residual stresses of analytical, numerical, and experimental were -379.1 Mpa,-456.6 Mpa, and -549.895 Mpa respectively. In the compressive residual stress field for analytical J-integral value was 0.0115 Mpa.mm and 0.901 Mpa.mm, and fatigue life was 83839.54 cycle and 9397.06 cycles for 0.0123 mm and 0.156 mm crack length respectively. For numerical the J-integral value was 0.040235 Mpa. mm and 0.0869 Mpa.mm, and the fatigue life was 15313.655 cycles and 10892.056 cycles for crack lengths 0.00413 mm and 0.0123 mm respectively. The results show that when the crack length is equal to the maxi mum compressive residual stress the J-integral value is low, and the fatigue life is longer. This indicates that shot peening is more beneficial in increasing fatigue life.