Edge notched disc test for evaluation of mode-I fracture toughness of brittle material

Abstract

In the current investigation, the fracture toughness of plexiglass specimens was accurately measured employing Edge Notched Disc (END) type specimens. Besides, the Notched Brazilian Discs (NBD) were used in order to validate the results of the conducted END experiments. Moreover, a numerical analysis was carried out on the END tests to verify the accuracy of the measured fracture toughness values. In the first stage, the splitting tensile test was used to accurately calibrate the micro-scale properties of the Flat Joint (FJ) model. In the second phase, the numerical simulation of END and NBD models was created, in which the notch lengths in END and NBD were set to 5, 15, 25, 40 and 10, 20, 30, 40, 50, 60 in millimeters, respectively. According to the obtained results, the considered FJ model is capable of making an accurate determination of the potential crack growth path and crack initiation stress like the experimentally obtained results for plexiglass specimens. It was also derived that lengthening the notch could not have a considerable effect on the fracture toughness of the models. The Tensile stress distribution on the failure surface of END test could be the main cause of the lower fracture toughness levels of END test. Besides, the same fracture extension patterns were seen from the experimental investigations and numerical simulations.