为了利用数字图像相关(DIC)方法对剪切带的位移和应变进行测量, 提出了一种修正的子区分割法。根据子区中心点的坐标和剪切带的倾角确定分割线, 对分割后的两个子区分别进行搜索, 并根据相关性较好的子区确定测点的位移。利用提出方法和传统DIC方法分别计算了源图片产生裂纹情形及变形产生剪切带情形下测点的位移和应变。结果表明, 在裂纹及剪切带附近, 修正的子区分割法的位移误差限分别为0.2像素及0.25像素, 传统DIC方法的位移误差限分别高达3像素及0.6像素; 在剪切带内, 修正的子区分割法的剪应变误差限小于或等于传统方法的; 修正的子区分割法具有较好的计算剪切带的位移和应变的能力。

An improved “subset splitting” method of the digital image correlation (DIC) method is proposed for measurements of displacements and strains of shear bands. A splitting line is determined by subset center coordinates and shear band inclination angle, correlation coefficients of two splitting subsets are obtained separately, and displacements of monitored points are determined according to higher correlation coefficients among two splitting subsets. Displacements and strains of monitored points for the source image where a crack or a shear band with strain gradients is produced are calculated by use of the proposed method and the traditional DIC method. Displacement error limits of the improved “subset splitting” method are 0.2 pixels and 0.25 pixels near by the crack and shear band, while those of the traditional DIC method are up to 3 pixels and 0.6 pixels. Shear strain errors of the improved “subset splitting” method is zero outside the shear band, which are less than those of the traditional DIC method. The improved “subset splitting” method is able to calculate displacements and strains near shear bands.