光弹性法测定圆轴弯扭组合变形复合应力强度因子

Photoelastic Determination of Mixed-mode Stress-intensity Factors in a Cylindrial Bar Subjected to Bending and Torsion Simultaneously

带环形裂纹的圆轴在弯扭组合变形时,离中性轴最远的裂纹尖端处于Ⅰ、Ⅲ型复合裂纹状态.三维光弹性应力冻结法是测定复杂三维问题的有效方法.本文采用机加工方法制作圆轴模型的裂纹,并利用双参数法测定I型应力强度因子,利用切片逐次削去法测定III型应力强度因子.与数值解比较,本文的实验结果误差较小,而且实验方法简便易行.

A cylindrical bar with cyclical crack is subjected to bending and torsion simultaneously. The crack top farthest away the median axis of the cross section is in a situation of mixed-mode Ⅰ 、Ⅲ crack. The three-dimensional photoelastic stress-frozen method is an effective method for determination of complex three-dimensional question. In this experiment, a cyclical crack for a cylindrical bar model is prepared with a mechanical process. In this paper, two-parameter method is used for determination of Ⅰ mode stress-intensity factor and a slice cutting step-by-step method is used for determination of Ⅲ mode stress-intensity factor. In comparison with a theory solution, the error of the experiment result is small. This method is simple and convenient.