Experimental evaluation of hole expansion ratio in DP600 steel sheet using a displacement controlled stopping criterion

This study presents the development and validation of an experimental procedure for determining the hole expansion ratio in DP600 steel sheets.The proposed method introduces a fracture criterion based on the observation of a single edge crack, characterized by one through-thickness fracture.The procedure was structured as a step-by-step algorithm inspired by numerical search strategies.The experimental application of the methodology led to the identification of a critical punch displacement of 9.52 mm, at which all tested samples exhibited exactly one complete fracture.The resulting hole expansion ratio values showed an average of 32.4% ± 0.2%, demonstrating good repeatability.The proposed method provides a precise and reproducible alternative for evaluating the formability and edge flangeability of sheared edges in hole expansion tests without automatic fracture detection systems.