Fracture-Toughness-Based Methodology for Determination of 3D-Printed Specimen Using Digital Image Correlation

This methodology investigates the determination of the fracture toughness of 3D-printed specimens under monotonic loading conditions. The application is based on the use of a Single Edge Notch Bending (SENB) specimen made by a 3D-printing process (17-4PH stainless steel). The load–displacement curves exhibited linear behavior until crack initiation, indicating that the Linear Elastic Fracture Mechanics (LEFM) can be used under a small-scale yielding assumption. This study extends a previous methodology, originally applied to a polymer, to a metal additively manufactured material. The methodology established in the paper represents a major outcome: the ability to characterize the fracture toughness of the material. This study extends our previous Digital Image Correlation-based methodology from thermoplastic polymers to 17-4PH stainless steel produced by metal additive manufacturing (ADAM). Its novelty lies in combining DIC with a finite element sub-model to evaluate fracture parameters, enabling accurate crack initiation detection in challenging metal AM specimens, and providing a methodology that can be generalized to other metals and AM processes. The aim of this study is to establish a robust DIC-based methodology for the identification of crack initiation and the determination of fracture toughness parameters (K_IC and J) in 3D-printed 17-4PH stainless steel produced by the ADAM process.