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|저자명||Chunghee Park Hoon Huh and Jungsu Park|
|Name||Proceedings of KIMST Annual Conference|
This paper is concerned with numerical simulations of PBX (polymer-bonded explosives) simulants at various strain rate conditions. Uniaxial compressive tests of two kinds of PBX simulants were conducted at a wide range of strain rates to investigate the effect of the strain rate on the strain hardening behavior of PBX simulants. Dynamic material testing machine (Instron 8801) was utilized for uniaxial compressive tests from quasi-static states to low strain rates ranging from 0.0001 s-1 to 1 s-1 and developed high speed material testing machine (HSMTM) was used for uniaxial compressive tests at intermediate strain rates ranging from 10 s-1 to 100 s-1. Split Hopkinson pressure bar (SHPB) was utilized for uniaxial compressive tests at high strain rates ranging from 1,250 s-1 to 3,870 s-1. The effect of the strain rate on the strain hardening behavior during uniaxial compressive deformation is quantitatively investigated from the experimental data at various strain rates. A new rate-dependent hardening model was proposed to model the effect of the strain rate on the strain hardening behavior of PBX simulants. The model is capable of representing the complicated strain rate effects on the strain hardening behavior for rate-sensitive materials with a second-order strain rate sensitivity function. The proposed model was implemented in LS-DYNA with user defined material model (UMAT). Finite element analyses of uniaxial compressive tests at various strain rates were conducted to validate the proposed model. The comparisons of FEA results with the experimental data show that the proposed model was successfully able to describe the significant effect of the strain rate on the strain hardening behavior of PBX simulants.