Crack tip monitoring of mode I and mode II delamination in CF/Epoxies under static and dynamic loading conditions using digital image correlation †

Digital image correlation has been used, in conjunction with Mode I and Mode II fracture mechanics tests under static and dynamic loading conditions, to determine the position of the crack front during interlaminar testing. A MATLAB code has been developed to post process the digital image correlation analysis to determine the experimentally measured crack position and these results have been compared to compliance-based predictions of crack position which do not use a physical measure of the crack length. Results have shown that the digital image correlation analysis has successfully tracked the crack position providing a physical measure of the crack front during static and dynamic testing for the calculation of fracture toughness values. This methodology, incorporating digital image correlation for crack position monitoring, was then expanded to analyses for fatigue tests showing that the physical crack length has a varied growth rate in comparison to the steady change in specimen compliance.