焦散线法求解裂纹应力强度因子的两种改进方法

为提高焦散线法求解应力强度因子的精度，提出了两种基于多点非线性最小二乘法的改进方法。文中推导了控制方程，编制了程序，阐述了实验技术。作为应用实例，对三种典型裂纹试件作了测试与处理。结果表明，用本文方法处理的结果比文［１］经典法的结果有很大改进。作者还对图像处理用于焦散线法应力强度因子的提取作了初步探讨［５

Two Improving Methods for Determining Stress Imtensity Factors by the Method of Caustics

In order to improving the accuracy of stress intensity factors (SIFs) solved from the caustic method,two approaches based on the multiple points nonlinear least square method are presented.In this paper,the control equations are derived,computation programs are organized and the experimental technique is described.As applied examples,three types of cracked specimens are tested and treated with above two improved approaches.It is shown that the results obtained by present approaches are greatly better than those obtained by classical method,see Ref..In addition,the extracting SIFs of cracks from the caustic pattern by using the digital image processing technique is also explored.