Determination of opening mode stress intensity factor in edge cracked specimen by means of digital shearography

In this paper, digital Shearography as a non-destructive technique is deployed to determine the opening mode stress intensity factor in an edge cracked specimen subjected to tensile loading. The optical setup was consisted of two in-plane illumination sources to determine purposed strain variable and consequently to obtain the opening mode stress intensity factor based on the assumptions of linear elastic fracture mechanics (LEFM). The speckle pattern images taken by a CCD camera were recorded and saved on a computer. In order to utilize the advantage of whole field Shearography and minimise the random experimental errors, the least square technique was used to obtain the stress intensity factors. A finite element model of the specific geometry was constructed, and ABAQUS v6.7 commercial software was used to perform the analyses. Comparison of the experimental data with the numerical results proved the credibility and potential of this non-destructive method as a practical measurement technique. The average difference between the results obtained from experiments and those of finite element analyses was nearly 8%.