基于数字图像相关法的应变测量理论误差分析

摘要

As a new strain measurement, digital image correlation has been applied to many fields because of its full - field measurement and easy operation. The algorithm was improved to limit the eight connected domains to a smaller subset. Matlab software was used to simulate speckle images to accurately control speckle displacement in theory. The accuracy of the improved digital image correlation method and its theoretical error factors were analyzed. The results show that the improved digital image correlation method improves the calculation precision by one order of magnitude. Through analyzing the different influence factors on the error, the most suitable calculation parameters were put forward when it is used in the practical measurement.%数字图像相关法作为新型的应变测量方法,因其具有全场测量、操作方便等优点已被广泛运用到各个领域.文中通过改进经典的数字图像相关算法,使二次曲面拟合时选择的八连域控制在一个更狭小的精确范围内.通过Matlab实现理论精确控制的模拟散斑图像,理论分析改进后的算法精度及其主要误差影响因素.结果表明,改进后的数字图像相关法理论计算精度提高一个数量级.通过分析不同误差影响因素的具体作用,提出在实际测量中应选择的最适合计算参数.