Prolonging the service life of nuclear power plants and more stringent safety requirements are increasing the need for miniature mechanical tests such as the Small Punch Test (SPT). This test was initially developed in the early 1980s at MIT and further developments with more extensive use were achieved by EPRI with a continuous program between 1990 and 1999.

The present investigation is first based on a finite element simulation benchmark between EPRI and CEA. This provided a reciprocal validation of the numerical simulation of this test for an A533 B steel at room temperature. The loading mode progressively evolves from bending towards biaxial membrane loading of the specimen. Strain energy density was also computed as the failure criterion and the maximum value observed at experimental crack initiation is about 116 MJ/m³.

A parametric finite element study was undertaken in order to evaluate the influence of factors such as specimen thickness, friction, yield strength, strain hardening coefficient, etc. Starting from this parametric study, an automatic routine was built which estimates the elastic-plastic Ramberg-Osgood stress strain relation. The need for standardization of this test will be underlined.