Calibration of ductile fracture criteria at negative stress triaxiality

• Novel specimen is designed to reach extremely low stress triaxiality.
• One original uncoupled ductile fracture criterion, KHPS, is proposed.
• Criteria calibration of AISI 1045 carbon steel and aluminium alloy 2024-T351.
• Fracture strain analysis together with their cut-off regions are discussed.

The aluminium alloy 2024-T351 and AISI 1045 carbon steel was examined in scope of uncoupled ductile fracture criteria calibration using newly designed specimen. Its novel geometry allowed to reach extremely low stress triaxialities. The analysis of fracture envelopes was carried out with comparison of each criteria cut-off regions after the calibration where one novel criterion, KHPS, has been introduced. Ductile fracture criteria implemented into the commercial finite element code Abaqus through user subroutine VUMAT were applied to simulation of compression of newly designed cylinder with specific recess to show the crack prediction ability using the element deletion technique. Crack initiation loci together with force responses were compared to experimental observations.