investigation of fracture in v-notched brittle polymers under pure shear loading

sudden fracture is one of the major failure modes in brittle materials. plexiglass (polymethyl methacrylate) is a well known brittle polymer, widely used in various industries. many types of notches, particularly v-shaped notches, are sometimes used in the components made of plexiglass. these notches can dramatically decrease the load bearing capacity of components due to the concentration of stress at the vicinity of their tips. the stress concentration may result in the crack nucleation and fracture from the tip of a v-notch. in the present paper, a set of notched specimens of plexiglass are subjected to pure mode ii loading, in order to determine the mode ii fracture toughness and the fracture initiation angle experimentally. these specimens contain rounded-tip v-notches with variable notch opening angles and different notch radii. the experimental results are then predicted by using a failure criterion, suggested for estimating brittle fracture in rounded-tip v-notches under pure shear deformation. a good agreement is shown to exist between the theoretical predictions and the experimental results.