Experimental evaluation of the strain intensity factor at the rigid line inclusion tip embedded in an epoxy matrix using digital image correlation

The strain intensity factor for a rigid line inclusion tip is experimentally determined using the digital image correlation (DIC) technique using multi-parameter displacement field equations. The multi-parameter displacement field equations for a rigid line inclusion are derived based on the Airy's stress function approach and are reported here in an elegant manner. The unknown coefficients in the multi-parameter equation, inclusion tip location, rigid body translations and rotation are determined using a linear least squares method in an over-deterministic manner. A rigid line inclusion specimen is prepared using 0.1 mm steel strip embedded in an epoxy matrix. Experiments are performed for two inclusion configurations when the embedding matrix is subjected to a remote tensile field. In the first configuration, the inclusion is placed along the tensile loading direction. In the second configuration, the inclusion is kept inclined to the loading direction. The experimentally obtained strain intensity factor agrees well with the analytical estimates with an error less than 6% for the seven parameter solution for both the configuration, thereby confirming the accuracy of the proposed methodology.