Estimation of Mixed-Mode I/II Fracture of U-Notched Polycarbonate Specimens Using the TCD and SED Methods

Polycarbonate (PC) has diverse applications in different industries such as transportation, electronics, biomedical and solar energy sectors. Polycarbonate is used as a material for structural components that are usually complex in shape and subjected to severe mechanical loading. The presence of notches such as holes, grooves, or cuts reduces the load-carrying capacity of structural components because of the stress concentration. Therefore, it is essential to understand the mechanical behavior of polycarbonate in the presence of different notch geometries. Machining of inclined notches at different angles to the applied load is simple, but this can produce complex mixed-mode I/II states that exist in real-life applications. The present study is performed on PC specimens with U-notches of different geometry. They differed in depths, radii, and angles. These specimens were tested under quasi-static loading, and selected specimens were analyzed using digital image correlation. Two linear elastic methods were used to analyze the fracture of U-notched PC specimens: the theory of critical distance with the point method (TCD-PM) and the strain energy density with the equivalent material concept (SED-EMC). Satisfactory estimates with the error between –4% and 2.5% were achieved using the TCD-PM method. Estimates derived by the SED-EMC method were mostly within the error of about ±13%.