On the basis of model selection from the pieces tested and according to elastic mechanics, the relation between minute displacement and welding residual stress is deduced.
对所测试件选取适当的模型，应用弹性力学理论，推导出微小位移与焊接残余应力的关系式。
2
The principle of the digital image correlation method was described, and the relation between the crack tip displacement and the stress intensity factor was deduced using least squares fitting.
介绍数字图像相关方法的基本原理，建立数字图像相关方法中位移场与裂纹尖端应力强度因子之间的关系。
3
Then, an analytical relation between axial average strain (or displacement) and axial compressive stress is obtained, which exhibits size effect.