Analysis of adiabatic shear coupled to ductile fracture and melting in viscoplastic metals

Fuente: arXiv
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Main Author: Clayton, John D.
Format: Preprint
Published: 2025
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author Clayton, John D.
author_facet Clayton, John D.
contents Material failure by adiabatic shear is analyzed in viscoplastic metals that can demonstrate up to three distinct softening mechanisms: thermal softening, ductile fracture, and melting. An analytical framework is constructed for studying simple shear deformation with superposed static pressure. A continuum power-law viscoplastic formulation is coupled to a ductile damage model and a solid-liquid phase transition model in a thermodynamically consistent manner. Criteria for localization to a band of infinite shear strain are discussed. An analytical-numerical method for determining the critical average shear strain for localization and commensurate stress decay is devised. Averaged results for a high-strength steel agree reasonably well with experimental dynamic torsion data. Calculations probe possible effects of ductile fracture and melting on shear banding, and vice-versa, including influences of cohesive energy, equilibrium melting temperature, and initial defects. A threshold energy density for localization onset is positively correlated to critical strain and inversely correlated to initial defect severity. Tensile pressure accelerates damage softening and increases defect sensitivity, promoting shear failure. In the present steel, melting is precluded by ductile fracture for loading conditions and material properties within realistic protocols. If heat conduction, fracture, and damage softening are artificially suppressed, melting is confined to a narrow region in the core of the band.
format Preprint
id arxiv_https___arxiv_org_abs_2502_10625
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Analysis of adiabatic shear coupled to ductile fracture and melting in viscoplastic metals
Clayton, John D.
Materials Science
74H10 (Primary), 74C20, 74H55, 74N05, 74R20 (Secondary)
Material failure by adiabatic shear is analyzed in viscoplastic metals that can demonstrate up to three distinct softening mechanisms: thermal softening, ductile fracture, and melting. An analytical framework is constructed for studying simple shear deformation with superposed static pressure. A continuum power-law viscoplastic formulation is coupled to a ductile damage model and a solid-liquid phase transition model in a thermodynamically consistent manner. Criteria for localization to a band of infinite shear strain are discussed. An analytical-numerical method for determining the critical average shear strain for localization and commensurate stress decay is devised. Averaged results for a high-strength steel agree reasonably well with experimental dynamic torsion data. Calculations probe possible effects of ductile fracture and melting on shear banding, and vice-versa, including influences of cohesive energy, equilibrium melting temperature, and initial defects. A threshold energy density for localization onset is positively correlated to critical strain and inversely correlated to initial defect severity. Tensile pressure accelerates damage softening and increases defect sensitivity, promoting shear failure. In the present steel, melting is precluded by ductile fracture for loading conditions and material properties within realistic protocols. If heat conduction, fracture, and damage softening are artificially suppressed, melting is confined to a narrow region in the core of the band.
title Analysis of adiabatic shear coupled to ductile fracture and melting in viscoplastic metals
topic Materials Science
74H10 (Primary), 74C20, 74H55, 74N05, 74R20 (Secondary)
url https://arxiv.org/abs/2502.10625