The optimum shot peening condition to improve fatigue strength for automobile transmission gears was investigated. Motion and clashing of shot particles were quantitatively described in relation to gear shape, and correlation with residual stress was investigated. Based on these results, computer simulation techniques for optimizing the shot peening conditions were proposed using the correlation between the fatigue strength and the residual stress which had been obtained in the previous work. Experimental results on the fatigue strength of gears coincided with the analytical prediction.
