Journal of the Korean Society for Aeronautical & Space Sciences (한국항공우주학회지)

The Korean Society for Aeronautical and Space Sciences (한국항공우주학회)
권호 표지
DOI QR코드

DOI QR Code

Material modeling of the temperature rise at high-strain-rate deformation

고변형률 변형하에서 재료 내부의 온도상승 계산을 위한 재료 모델링

  • 최덕기 (단국대학교 기계공학과) ;
  • 유한규 (단국대학교 기계공학과 대학원)
  • Published : 2004.09.01
Download PDF
⟨ Previous Next ⟩

Abstract

High velocity impacts are accompanied with large deformations, which generate a large amount of heat due to plastic works, resulting in a significant temperature rise of the material. Because the elevated temperature affects the dynamic properties of materials, it is important to predict the temperature rise during high-stram-rate deformations. Both existing vacancies and excess vacancies are credited to the stored energy, yet it is difficult to distinguish one from another in contribution to the stored energy using macroscopic level materials models. In this study, an atomistic material model for fee materials such as copper is set up to calculate the stored energy using molecular dynamics (MD) simulations. It is concluded that excess vacancies play an important role for the stored energy during a high-strain-rate deformation.

고속으로 비행하는 물체가 다른 물체와 충돌하는 경우에는 극히 짧은 시간에 커다란 변형이 일어나게 된다. 고변형률 변형 (high-strain-rate deformation) 에서는 소성변형이 일어나면서 상당한 열을 발생시키고 재료의 온도를 상승시킨다. 온도의 상승은 재료의 동적인 물성에 많은 영향을 미치게 되므로, 변형 시의 온도상승을 예측하는 것은 매우 중요하다. 변형시의 온도상승은 주로 전위(dislocation)의 움직임과 공공(vacancy)으로 인한 재료내의 저장에너지와 밀접한 관계를 갖게되므로, 저장 에너지의 양을 파악하는 것은 매우 중요하다. 고변형률 변형시 전위가 빠르게 움직이면서 평형상태에서의 경우보다 많은 파공공 (excess vacancies) 을 발생시키게 된다. 본 논문에서는 과공공을 포함하는 미시적 재료 모텔을 구성하고 분자동역학 (molecular dynamics, MD) 기법을 사용하여 면십입방격자 (fcc) 구조를 가지는 재료 (구리)에 대한 저장 에너지를 계산하였다.

Keywords

References

  1. Meyers, M. A , Dynamic behavior of materials, John Wiley & Sons, Inc., New York, 1994, pp.375-378.
  2. Rohatgi, A and Vecchio, K. S., "The variation of dislocation density as a function of the stacking fault energy in shock-deformed FCC materials," Mater. Sci. Eng. A, Vol. 328, 2002, pp . 256-266. https://doi.org/10.1016/S0921-5093(01)01702-6
  3. Preston, D. L., Tonks, D. L., Wallace, D. C, "Model of plastic deformation for extreme loading conditions", J. Appl. Phys., Vol. 93, 2003, pp . 211-220. https://doi.org/10.1063/1.1524706
  4. Nemat-Nasser, S., Isaacs, J. B. and Starrett, J. E., "Hopkinson techniques for dynamic recovery experiments," Proc, R. Soc. London A, Vol. 435, 1991, pp. 371-391. https://doi.org/10.1098/rspa.1991.0150
  5. Kapoor, R. and Nernat-Nasser, S., "Determination of temperature rise using high strain rate deformation," Mech. Mater., Vol. 27, 1998, pp . 1-12. https://doi.org/10.1016/S0167-6636(97)00036-7
  6. Oliferuk, W., Swiatnicki, W.A. and Grabski, M. W., "Effect of the grain size on the rate of energy storage during the tensile deformation of an austenitic steel," Mater. Sci. Eng. A, Vol. 197, 1995, pp . 49-58. https://doi.org/10.1016/0921-5093(94)09766-6
  7. Nemat-Nasser, S., Guo, W. G. and Kihl, D. P., "Thermomechanical response of Al-6XN stainless steel over a wide range of strain rates and temperatures," J. Mech. Phys. Solids, Vol. 49, 2001, pp. 1823-1846. https://doi.org/10.1016/S0022-5096(00)00069-7
  8. Pantleon, W., Francke D., Klimanek, P., "Modelling adiabatic heating during high-speed deformation," Comput. Mater. Sci., Vol. 7, 1996, pp. 75-81. https://doi.org/10.1016/S0927-0256(96)00063-8
  9. Meyers, M. A., Benson, D. J., Vohringer, O ., Kad, B. K., Xue, Q. and Fu, H. H., "Constitutive description of dynamic deformation: physically-based mechanisms," Mater. Sci. Eng. A, Vol. 322, 2002, pp. 194-216. https://doi.org/10.1016/S0921-5093(01)01131-5
  10. Stroh, A N., "A theoretical calculation of the stored energy in a work-hardened material", Proc. Roy. Soc. A, 1953, pp. 391-400.
  11. Clarebrough, L. M., Hargreaves, M. E., Michell, D., West, G. W., "The determination of the energy stored in a metal during plastic deformation", Proc. Roy. Soc. A, Vol. 215, 1952, pp. 507-524. https://doi.org/10.1098/rspa.1952.0228
  12. Heino, P., Hakkinen, H. and Kaski, K., "Molecular-dynamics study of copper with defects under strain," Phys. Rev. B, Vol. 58, 1998, pp. 3197-3204. https://doi.org/10.1103/PhysRevB.58.3197
  13. Zhou, S. J., preston, D. L., Lomdahl, P. S. and Beazley, D. M., "Large-scale molecular dynamics simulations of dislocation intersection in copper," Science, Vol. 279, 1995, pp. 1525-1527. https://doi.org/10.1126/science.279.5356.1525
  14. Choi, D. K. and Kim, J. W., "Calculation of stress intensity factors using three-dimensional molecular dynamics simulation," Metals and Materials, Vol. 4, 1998, pp. 920-924. https://doi.org/10.1007/BF03026424
  15. 최덕기, 류한규, "PC Network Cluster를 사용한 대규모 재료 시뮬레이션에 관한 연구", 한국항공우주학회지, 제30권, 제5호, 2002, pp.15-23.
  16. Rapaport, D. C., The Art of Molecular Dynamics Simulation, Cambridge University Press, Cambridge, UK, 1995.
  17. Johnson, R. A, "Empirical potentials and their use in the calculation of energies of point defects in metals," J. Phys. F, Vol. 3, 1973, pp. 295-321. https://doi.org/10.1088/0305-4608/3/2/004