Abstract:

An easy-to-implement and effective “special stereo-digital image correlation (SS-DIC)” method was proposed by using the virtual field method (VFM) to accurately identify material constitutive parameters. The left camera in the SS-DIC system was placed with its optical axis normal to the specimen surface, while the sensor of the right camera was inclined with respect to the specimen surface in experiment. Pure shear tests of the prismatic aluminum specimens verified the effectiveness and accuracy of the proposed method. Experimental results show that the constitutive parameters identified by the VFM using the SS-DIC are more accurate (relative errors of both Young's modulus and Poisson's ratio are less than 4%) than those identified by the VFM by using two dimensional digital image correlation (2D-DIC) (relative errors of both Young's modulus and Poisson's ratio are more than 6%). The SS-DIC can not only deliver accurate deformation measurement without being affected by the unavoidable out-of-plane movement/rotation of a test specimen, but can also ensure evenly distributed
calculation data in space and leads to simple data processing in the identification of constitutive parameters.

Key words: material constitutive parameter identification , mechanics inverse problem , digital image correlation
 (DIC) ,  special stereo-digital image correlation (SS-DIC) , virtual field method (VFM) , experiment