非均匀变形测量环绕测点子区分割DIC方法研究  

Study of the DIC method of subset splitting always surrounding the monitored point for non-uniform deformation measurement

作　　者：王学滨 张博闻[2] 董伟 孙云滨 WANG Xuebin;ZHANG Bowen;DONG Wei;SUN Yunbin(Institute of Computational Mechanics,Liaoning Technical University,Fuxin,Liaoning 123000,China;College of Mechanics and Engineering,Liaoning Technical University,Fuxin,Liaoning 123000,China)

机构地区：[1]辽宁工程技术大学计算力学研究所,辽宁阜新123000 [2]辽宁工程技术大学力学与工程学院,辽宁阜新123000

出　　处：《中国矿业大学学报》2021年第6期1212-1220,共9页Journal of China University of Mining & Technology

基　　金：国家自然科学基金项目(51874162)。

摘　　要：为了改善传统数字图像相关(DIC)方法的剪切带边界附近位移测量精度较差和现有子区分割方法分割线不易确定的缺点,本文提出了环绕测点子区分割一阶DIC方法,其实质是将相关性不好的原始子区以测点为中心有限细分,利用一阶DIC方法搜索到相关性最好的后代子区(在剪切带边界附近且位于变形相对均匀区域).通过对基于梯度塑性理论和仿射变换制作的虚拟剪切带变形过程中的位移进行测量,验证了本文方法的正确性,并与基于粒子群优化和Newton-Raphson迭代的粗-细方法的结果进行了对比.结果表明:当粗-细方法的误差大时,本文方法可以有效改善测量位移精度;对于通常大小的子区,最大分割次数取为1即可.以布置测线的方式,定量比较了单轴压缩黏土试样变形破坏过程中2种方法的最大剪切应变,通过考察所拍摄图像,进一步确认了本文方法的有效性.For traditional digital image correlation(DIC) methods, measurement accuracies of displacements near shear band boundaries are not high. The splitting line in the subset splitting method cannot be easily determined in the vicinity of shear bands. In the present paper, the first-order DIC method where splitted subsets always surrounding the monitored point was proposed to improve measurement accuracies of displacements near shear bands. The essence of the method is to use the first-order DIC method to search the best subsets(near the shear band boundaries and in the relatively uniform deformational region) by finitely splitting the original subset with poor correlation. The gradient-dependent plasticity and affine transformation were used to generate a fictious shear band. To validate the present method, displacements during shear were measured, and the present results were compared with those of the coarse-fine methods based on the particle swarm optimization and Newton-Raphson iteration. The results show that for high errors in the coarse-fine method, the present method can improve measurement accuracies of displacements, but for normal subset size, the maximum number of divisions is suggested to be one. A few monitored lines are arranged to compare differences of maximum shear strains between two kinds of methods for a clay specimen in uniaxial compression during the deformation and failure process. The present method is further validated through examining images shot in tests.

关 键 词：岩土材料 非均匀变形 剪切带 精细测量 子区分割 分割次数 仿射变换 梯度塑性理论 

分 类 号：TU454[建筑科学—岩土工程]