超声波加工中的动力效应与裂纹分析

Dynamic Effect and Crack Analysis of Ultrasonic Machining

发电设备的陶瓷部件主要用超声波进行加工,材料的去除率直接影响加工的效率。在加工中工件材料的表面受到磨料的碰撞,接触区域将发生变形。这种局部变形不能立即传遍整个工件,而是以波的方式逐渐传播。当应力大于其压缩强度后,接触面下面的材料开始破碎,材料中产生的裂纹沿撞击方向逐渐扩展。破裂是由于应力波从拐角的两个面反射结果造成的高度应力集中而发生的,实验证明一般都会产生高强度的局部拉伸应力。还从能量方面对裂纹的产生和扩展做出分析,推导出裂纹扩展的临界应力。

The ceramic parts of power equipment are mainly machined by ultrasonic.In ultrasonic machining,machining efficiency is directly effected by material removal rate.When the surface of the workpiece is impacted by the abrasive material,the contact area will be deformed.This local deformation is not immediately spread throughout the whole piece,but spread means is by the wave.When the stress is beyond its compressive strength,the material below the contact surface starts to crumble and the cracks in the material expand from the direction of the impact gradually.Rupture results from the concentration of the high-degree stress formed by the stress wave reflecting from the corner of two sides.The experiment proves that the high-intensive local tensile stress will produce generally.The paper analyzes the formation and the expansion of the crack from the energy,then gets the critical stress formula of the crack.