A correction method for determining crack opening displacement and crack length based on digital image correlation technology

Digital image correlation (DIC) technology can obtain the full-field displacement and strain of the material surface without contact. When studying the fracture behavior of materials, it is usually crucial to accurately determine the crack opening displacement and crack propagation length at every loading stage. Although the displacement field and strain field at each point can be procured by DIC technology, it is impossible to determine the crack width and crack propagation length directly. So it is necessary to combine post-processing technology to determine the crack parameters. In order to improve the accuracy of crack identification, an advanced post-processing method for determining crack opening displacement based on DIC displacement field data is proposed in this paper. In the proposed method, not only personal error can be avoided, but also the effect of material deformation at the crack tip is effectively removed. In order to verify the proposed method, 3-point bending test of a concrete beam were conducted. The results show that, based on the proposed processing method, the crack opening displacement and crack length at different loading stages during the test process can be accurately determined.