Fracture toughness characterization through notched small punch test specimens

TL;DR

This paper introduces a new method using notched small punch tests combined with finite element simulations to evaluate fracture toughness, providing a practical alternative to conventional testing methods.

Contribution

A novel methodology integrating notched small punch tests with numerical simulations for accurate fracture toughness assessment is proposed and validated.

Findings

Effective characterization of fracture toughness in CrMoV steel.

The method captures differences in material toughness.

Limitations discussed for low toughness materials.

Abstract

In this work a novel methodology for fracture toughness characterization by means of the small punch test (SPT) is presented. Notched specimens are employed and fracture resistance is assessed through a critical value of the notch mouth displacement {\delta^SPT}. Finite element simulations and interrupted experiments are used to track the evolution of {\delta^SPT} as a function of the punch displacement. The onset of crack propagation is identified by means of a ductile damage model and the outcome is compared to the crack tip opening displacement estimated from conventional tests at crack initiation. The proposed numerical-experimental scheme is examined with two different grades of CrMoV steel and the differences in material toughness captured. Limitations and uncertainties arising from the different damage phenomena observed in the lowest toughness material examined are thoroughly discussed.