用实验——有限元法确定圆环中残余应力的分布

Determination of Residual Stress Distribution in a Ring by Experiment——Finite Element Method

1 简介为提高高压圆筒的承载能力和疲劳强度,常采用自增强处理工艺,使简体内壁产生残余压应力。残余应力的无损检测方法有X射线法、磁测法、超声法等。X射线法和磁测法只能测定试件表面一薄层材料的残余应力,超声法也只能测定简单应力状态的构件(如螺栓的轴向拉力),而对于象厚壁圆筒经自增强处理后的残余应力,用该法测定十分困难。

The circular ring is cut from its external surface along a radial direction by electrospark wire-electrode cutting. When the cutting is at various depths, the values of strain at the internal and external surfaces of the ring are measured. Suppose that a couple of the circumferential forces, which are equal to a unit and along the opposite direction, are exerted at each couple of nodes of the two sides of the ring cutting slot, respectively, you can use the FEM to calculate stress values at the internal and external surfaces under the forces (the stress values are called the influence coeffecients of cutting depth here ). Based on the measuremental strain values and their corresponding influence coefficients the residual stress distribntion in the original ring can be derived.