Damage modeling in Small Punch Test specimens

TL;DR

This paper investigates ductile damage modeling in Small Punch Tests, focusing on notch shape effects, parameter extraction methods, and the use of Gurson-Tvergaard-Needleman models to understand crack mechanisms, aiding material assessment with limited samples.

Contribution

It introduces a methodology for extracting ductile damage parameters from notched SPT specimens and analyzes the influence of notch shape on test constraints and damage behavior.

Findings

Notch shape significantly affects triaxiality and constraint conditions.

A new method for extracting micromechanical damage parameters from load-displacement curves.

Gurson-Tvergaard-Needleman model effectively predicts crack initiation and propagation in SPT.

Abstract

Ductile damage modeling within the Small Punch Test (SPT) is extensively investigated. The capabilities of the SPT to reliably estimate fracture and damage properties are thoroughly discussed and emphasis is placed on the use of notched specimens. First, different notch profiles are analyzed and constraint conditions quantified. The role of the notch shape is comprehensively examined from both triaxiality and notch fabrication perspectives. Afterwards, a methodology is presented to extract the micromechanical-based ductile damage parameters from the load-displacement curve of notched SPT samples. Furthermore, Gurson-Tvergaard-Needleman model predictions from a top-down approach are employed to gain insight into the mechanisms governing crack initiation and subsequent propagation in small punch experiments. An accurate assessment of micromechanical toughness parameters from the SPT is of tremendous relevance when little material is available.