Investigation of fracture parameters of edge V-notches in a polymer material using digital image correlation

In this study, digital image correlation is employed to analyze the displacement field around edge V-notches in a polymethyl methacrylate (PMMA) sample with and without tip cracks. First stress intensity factor (SIF) is obtained by substituting experimental displacement field data in the series expansion of the Williams approach and solving the corresponding least squares problem. To study the effects of geometric parameters on the calculated SIF, various opening angles and depths of V-notch are considered for different tip crack length values. Convergence behavior of the results is studied by examining the influence of minimum radius of the data-points extraction region and the number of terms considered in the Williams expansion. It is demonstrated that the results converge after considering two or three terms of the series depending on the value of V-notch opening angle. Also, it is shown that the presence of tip cracks increases the minimum required radius of the data extraction zone.