超声辅助磨削陶瓷材料的裂纹产生与扩展仿真研究

基于光滑质点流体动力学(SPH)法,研究超声磨削陶瓷材料过程中磨粒冲击工件的裂纹产生及扩展情况,揭示不同超声冲击速度下材料的去除特性及表面层损伤规律。仿真结果表明:磨粒以不同速度压入工件一定深度后,工件开始产生侧向裂纹和径向裂纹;随着冲击速度的增大,工件材料受冲击部位周围的局部崩碎现象明显减少,产生侧向裂纹时磨粒压入工件的临界深度减小,而产生径向裂纹时的临界深度无明显变化。磨粒压入工件的深度增加,观察两种裂纹的扩展情况发现:冲击速度提高,侧向裂纹扩展速度变慢、尺寸减小,而径向裂纹则无明显变化。证实了随着冲击速度的提高,即超声效果加强时,工件的塑性域去除范围增大,但不会引起表面层损伤增大,最终表面质量得到提高。

Simulation Investigation on Crack Initiation and Propagation in Ultrasonic Assisted Grinding of Ceramics Material

Based on smoothed particle hydrodynamics (SPH) method, the initiation and propagation of the cracks in the process of single abrasive impacting a workpiece are simulated during ultrasonic assisted grinding of ceramics material, and the removal characteristics and surface layer damage of material under different ultrasonic impact speeds are revealed. The simulation results show that the lateral and radial cracks occur initially when single abrasive is pressed into the workpiece at a certain depth under different impact speeds. With the increase in impact speed, the fractures in action area are significantly reduced, and the critical pressed depth of abrasive is decreased when a lateral crack is generated, while the critical pressed depth of abrasive is unchanged obviously when a radial crack is generated. By observing the propagation of the two kinds of crack with the increase in the pressed depth, it can be found that the propagation velocity and geometric size of lateral crack decrease, while the radial crack has no obvious change. The results show that the ductile region removal of ceramics material is enhanced with the increase in impact speed, while the damage of surface layer is not enlarged, and the surface quality is improved.