用于材料本构参数识别的特殊三维数字图像相关方法

Special Stereo-digital image correlation method for meterial constitutive parameter identification

用虚场方法(VFM)识别材料本构参数时,为了得到准确的结果,提出了一种易实现且有效的"特殊三维数字图像相关(SS-DIC)"方法。将三维数字图像相关测试系统中左相机正对被测物体、右相机斜对被测物体进行全场变形测试。用铝合金试件纯剪切试验,验证了本文提出方法的有效性。结果表明:基于SS-DIC的VFM识别结果的精度(弹性模量和Poisson比相对误差均小于4%)优于基于两维DIC的参数识别结果(弹性模量和Poisson比相对误差均大于6%)。该方法既保证了全场变形测试结果不受试验中试件离面位移和离面转动的影响,又能直接获得在空间上均匀分布的变形信息,参数识别时数据处理简单。

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（2 D-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.