超声珩磨中声空泡溃灭微射流冲击特性的研究

Study on Impact Characteristics of Micro-Jet from Acoustic Bubble Collapse in Ultrasonic Honing

超声珩磨加工过程中会产生强烈的声空化现象,近壁空泡溃灭会产生高速微型射流,冲击材料表面造成变形损伤.为探究空泡溃灭微射流的冲击特性及其对壁面材料的作用,选用sph-fem方法,建立微射流冲击壁面模型,进行仿真分析,并设计超声珩磨谐振系统空化试验.结果表明：微射流冲击壁面后形成高速侧向射流,且其最大速度可达到冲击速度的1.593倍,高速侧向射流对材料产生剪切作用;微射流冲击中后期射流中部粒子在激波作用下反向运动向上凸起;微射流冲击后壁面产生直径约8μm,深约0.173μm的微型凹坑,凹坑边缘有材料隆起,射流边缘冲击效应最强;试验中单微射流冲击下产生的凹坑直径在6～12μm之间,与仿真分析结果一致.

Strong acoustic cavitation appears in ultrasonic honing processing,bubble collapse near the wall produces high speed micro-jet impacting on the material surface,which causes deformation damage.To explore the impact characteristics of bubble collapse micro-jet and its effect on the wall material,sphfem method was applied,the model of micro-jet impacting on a wall was established,simulation analysis was conducted,and a cavitation test of the ultrasonic honing vibration system was designed.Results show that high-speed lateral jet formed when micro-jet impacted on a wall,its maximum speed could reach 1.593 times of the impact velocity,which generates shear action on the material;the middle particles of micro-jet reverse movement and raise up under the action of shock wave in the middle and later periods;a micro pit appears with diameter 8μm and depth 0.173μm on a wall after micro-jet impact,material plastically uplift at the edge,and the impact effect is the strongest at the edge of the jet;The diameter of a pit produced by a single micro-jet impact is between 6μm and 12μm,this is agreed with the simulation analysis results.