二维数字图像相关测量中离面位移引起的误差分析

二维数字图像相关方法作为一种非接触全场变形测量的光学方法,在工程上有着广泛的应用.由于其假设物体只发生面内位移,而实验中往往存在离面位移,从而引起测量误差.本文针对这一问题利用了针孔模型,从理论上分析了离面位移对普通镜头测量结果的影响,通过铝块平移实验验证了理论分析的正确性.利用提出的理论模型修正橡胶材料的变形测量结果,并与远心镜头测量结果进行对比,发现修正后的普通镜头测量的结果更接近远心镜头测量的结果.最后,本文根据理论分析和实验验证,给出了减小或消除离面位移造成误差的方法.

Analysis of the Error Caused by Off-Plane Displacement in Two-Dimensional Digital Image Correlation Measurement

Two-dimensional Digital Image Correlation (2D-DIC) method is a non-contact optical full-field deformation measurement method, and is widely applied in engineering. It assumes that the specimen has only in-plane displacement. However, the off-plane displacement often occurs in experiment. So the measurement error is inevitable. A pinhole model is applied, and the influence of off-plane displacement on measurement results is theoretically analyzed in this paper. Experimental results of aluminum block translation certify the theoretical analysis. The modified large deformation measurement results of rubber by normal lens are closer to the telecentric lens measurement results. At last, a reasonable way to decrease even eliminate the error caused by off-plane displacement is suggested in this paper.