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Analyisis of Adiabatic Shear Band Formation by an Elasto-Plastic Finite Element Method with Explicit Time Integration (외연적 시간적분 탄소성 유한요소법에 의한 단열전단밴드의 해석)
||1998||||||||||Sang-Soon Cho||15||Adiabatic plastic deformation plays an important role in such widely diverse areas as ballistic impact, explosive fragmentation, high velocity shaping and forming, machining. All of the adiabatic shearing phenomena are based on the following two facts. One is that approximately 90% of the plastic work is converted to heat and the other is that the flow stress of most metals is quite sensitive to temperature so that it decreases as the temperature increases. Also adiabatic shear band usually accelerates fracture either in ductile or brittle manner. In this study, dynamic elasto-plastic finite element analysis is carried out using explicit time integration which is widely used for providing practical solutions since it improves the convergence, the memory size and the computing time. In order to integrate the constitutive equations over a time step PPEC method is used, by which the stress could be accurately calculated in a single step with no iteration. The shear band propagation is analyzed by a finite element code developed. The code adopts Johnson-Cook model to consider the effect of strain hardening, strain rate hardening and thermal softening. The analysis is studied the effect of the material constants in Johnson-Cook model on the adiabatic shear band. The results demonstrate the increase of the material constant A accelerates the shear band formation while the decrease of the material constant B, n, C, m accelerates the shear band formation.