Exploring stress states of notched small punch test specimens with different notch types
Notched small punch test (SPT) specimens with different types of notches have been adopted by many researchers to understand the fracture parameters of materials. However the specimen geometries have not been standardized and the effects of notch type on mechanical properties, failure mechanisms, and stress state of the tested materials need to be explored. The current work systematically studied the deformation behavior of a CuCrZr alloy using SPT specimens with side notch, groove notch, and circle notch, as well as different notch sizes using experimental and finite element simulation methods. Based on SPT load-displacement curves, the circle notch causes the greatest decrease in load-carrying capacity as it significantly affects the member stretching stage, and the differences between the side notch and groove notch are dependent on the notch size. Subsequently, the strain distributions around the centre line and on the notch arc are depicted to reveal the variation of strain distribution and failure mechanism with notch type and notch size. Moreover, quantitative characterizations of stress state parameters including stress triaxiality and Lode angle parameter at the notch tip and the specimen centre point are provided for the first time for notched SPT specimens with three notch types. This study comprehensively reveals the effects of notch type and size on the mechanical properties and stress state of SPT specimens, providing an essential reference for the utilization and standardization of notched SPT specimens.