Numerical Study on Ductile Failure Behaviours of Steel Structures under Quasi-Static Punch Loading

Abstract

A reliable finite element procedure to simulate shear-dominated ductile fractures in large-scale, thin-walled steel structures is still evolving primarily due to the challenges in determining the failure criterion of metal materials under complex stress states. This paper aims to examine the accuracy of the modified Gurson–Tvergaard–Needleman (GTN) model considering the shear failure in simulating the ductile fracture of steel plate structures under quasi-static punch loading. The modified GTN damage models are performed by the ABAQUS user-defined material subroutine (VUMAT). The void-related parameters and shear damage parameters of Xue’s and the N-H modified GTN models are calibrated from test specimens with various geometries corresponding to different stress triaxiality and shearing conditions. The damage evolution associated with shearing of voids in the modified GTN models has strong influences on the stress triaxiality versus plastic strain under complex stress states, especially for the shear-dominated loading conditions. Based on the original GTN model, Xue’s and the N-H modified GTN model with calibrated material parameters, a numerical comparative study examines the ductile fracture of steel non-stiffened plates and stiffened plates under punch loading. Benchmarked against the experimental studies, the numerical simulations demonstrate that the shear-driven void evolution in the modified GTN model imposes significant effects on the load–displacement responses as well as the onset and extension of ductile fractures in steel plates under punch actions. The N-H modified model with calibrated shear damage parameters shows a better correlation with the ductile fractures in steel plates observed in the experiment than the original GTN model and Xue’s modified GTN model. As a result of this study, the modified GTN model considering shear action can be applied for practical applications in the crashworthiness assessment of ship collision and grounding.

Keywords

• steel structures
• ductile fracture
• modified GTN model
• shear failure
• punch loading