Numerical Analysis on Residual Stress Field of Brake Discs by Ultrasonic Shot Peening

In order to improve the lifetime of high-speed train brake disc, the ultrasonic shot peening can be used to strengthen surface made of cast steel. According to the principle of ultrasonic shot peening equipment, biased structure FEM models for single pellet and multiple pellets are established based on Johnson-Cook equation. Explicit dynamic analysis of ANSYS / LS-DYNA is used to study effects on the residual stress of brake disc under shot peening of different parameters. The FEM analysis shows that the higher density material, the larger diameter and the higher velocity of projectile can produce the deeper total compressive stress layer under the condition of single projectile. Under the condition of multiple projectiles, its average of residual compressive stress impact is larger than that single projectile. the maximum tensile stress decreases with the increase of surface coverage, which improves the surface quality of the brake disc. The maximum residual stress can be increased by increasing the overlap ratio of projectiles. The maximum residual stress increases slowly and finally tends to be constant after repeated striking for certain times. Above results shows the strengthening of materials after ultrasonic peening. The FEM results about shot peening parameters can provide a reasonable basis for actual tests of ultrasonic shot peening equipment in the future, so that better ultrasonic peening effects of the surface of train brake disc can be achieved.