An energy equivalent method to determine the stress–strain relations of ductile materials by small punch testing

Abstract

ABSTRACT Small punch testing (SPT) is a very promising method to acquire the mechanical properties of miniaturized structures and in-service structures. In this study, an SPT based on energy equivalent (SPT-EE) method is proposed to acquire the constitutive curves of materials according to the stages II and III load–displacement (P-h) curves of classical SPT samples, respectively. Further, lots of numerical simulations were performed to verify the effectiveness of SPT-EE method. The results demonstrate that the constitutive curves predicted by the SPT-EE method according to stages II and III P-h relations of SPT simulated experiments agree well with the initial hypothetical material input by numerical simulation software. Analogously, the SPT verification tests of P92 and 30CrNiMoA were conducted, and the corresponding stress–strain curves were successfully predicted by the SPT-EE method on the basis of the stages II and III P-h curves of SPT samples. It can be observed that the predicted constitutive curves coincide with the curves acquired by the finite-element-analysis aided testing (FAT) method in different strain ranges. Finally, the novel SPT-EE method is successfully applied to predict the constitutive curves of in-serviced hollow structures.