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Lookup NU author(s): Professor Zhiqiang Hu
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© 2018 ASME. The NVA mild steel is a commonly used material inshipbuilding, which possesses good ductility character.However, the description of ductile fracture process for NVAsteel in numerical simulation is still a challenging task. A newmethod to predict the critical void volume fraction fc ofGurson-Tvergaard-Needleman (GTN) model is introduced inthis paper.GTN-model is one of the well-known micromechanicalmodels for ductile fracture. The traditional plasticity theoryassumes that the plastic volume is incompressible and that theyield of the material is independent of the hydrostatic stress,whereas the yield surface of the GTN-model takes the effectof the macroscopic hydrostatic stress into account. The yieldsurface is reduced with the increase of the void volumefraction, which can reflect the deterioration characteristics ofthe material with development of damage during thedeformation process. Therefore, GTN-model is a promisingmathematical model for describing the ductile fracture processof the ship structures during accidental scenarios of collisionand grounding.The traditional way to determine fc of GTN-model isusing the inverse method directly, which has a high degree ofuncertainty. A new method based on Hill, and Bressan &Williams's assumptions proposed in this paper solve thisproblem effectively. Besides, the combined of Voce and Swiftconstitutive model is used to describe the mechanical propertyof the NVA material.Furthermore, numerical simulations were also conductedwith code LS-DYNA by developing the user-definedsubroutine. It is found that the model can predict the structuraldamage quite accurately, which proves its feasibility of beingapplied in the research of structural responses in ship collisionand grounding accidents.
Author(s): Song Z, Hu Z
Publication type: Conference Proceedings (inc. Abstract)
Publication status: Published
Conference Name: 37th International Conference on Ocean, Offshore and Arctic Engineering - OMAE
Year of Conference: 2018
Online publication date: 22/06/2018
Acceptance date: 17/06/2018
Publisher: American Society of Mechanical Engineers (ASME)
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