DOI QR코드

DOI QR Code

Modeling on the Nonlinear Rate Sensitivity of Flow Stress

유동응력의 비선형 속도 민감도에 대한 모델링

  • 호광수 (계명대학교 기계자동차공학부)
  • Published : 2004.06.01

Abstract

Most metallic materials and alloys show rate independence or negative rate sensitivity in some temperature region when dynamic strain aging occurs. It is generally recognized that negative rate sensitivity is an essential feature of dynamic strain aging that can depend on strain and/or strain rate. The unified viscoplasticity theory based on overstress is applied to reproduce a change of rate sensitivity type that depends on strain or strain rate. This is accomplished through the introduction of a single new term in the growth law of the equilibrium stress, which is a tensor valued state variable of the model. It is also shown that the new term can be used to reproduce a dramatic increase of rate sensitivity in dynamic plasticity.

Keywords

Constitutive Equations;Rate Sensitivity;Dynamic Strain Aging;Flow Stress;Dynamic Plasticity

References

  1. Ho, K. and Krempl, E., 2000, 'Modeling of Positive, Negative and Zero Rate Sensitivity by Using the Viscoplasticity Theory Based on Overstress (VBO),' Mechanics of Time-Dependent Materials, Vol. 4, pp. 21-42 https://doi.org/10.1023/A:1009850608336
  2. Ho, K. and Krempl, E., 2002, 'Extension of the Viscoplasticity Theory Based on Overstress (VBO) to Capture Non-Standard Rate Dependence in Solids,' International Journal of Plasticity, Vol. 18, pp. 851-872 https://doi.org/10.1016/S0749-6419(01)00011-0
  3. Swearengen, J.C., Lowe, T.C. and Lipkin, J., 1985, 'Constitutive Equations for Rate-Dependent Plasticity,' Annual Review of Materials Science, Vol. 15, pp. 249-270 https://doi.org/10.1146/annurev.ms.15.080185.001341
  4. Freed, A.D., Chaboche, J.-L. and Walker, K.P., 1991, 'On the Thermodynamics of Stress Rate in the Evolution of Back Stress in Viscoplasticity,' NASA TM-103794
  5. Cottrell, A.H., 1953, 'A Note on the Portevin-LeChatelier Effect,' Philosophy Magazine, Vol. 44, pp. 829-832
  6. McCormick, P.G., 1972, 'A model for the Portevin-LeChatelier Effect in Substitutional Alloys,' Acta Metallurgica, Vol. 20, pp. 351-354 https://doi.org/10.1016/0001-6160(72)90028-4
  7. Kubin, L.P. and Estrin, Y., 1985, 'The Portevin-LeChatelier Effect in Deformation with Constant Stress Rate,' Acta Metallurgica, Vol. 33, pp. 397-407 https://doi.org/10.1016/0001-6160(85)90082-3
  8. Stout, M.G. and Follansbee, P.S., 1986, 'Strain Rate Sensitivity, Strain Hardening, and Yield Behavior of 304L Strainless Steel,' Journal of Engineering Materials and Technology, Vol. 108, pp. 344-353 https://doi.org/10.1115/1.3225893
  9. Clifton, R.J., 1990, 'High Strain Rate Behavior of Metals,' Applied Mechanics Review, Vol. 43, pp. S9-S22 https://doi.org/10.1115/1.3120862
  10. Bodner, S.R. and Rubin, M.B., 1994, 'Modeling of Hardening at Very High Strain Rates,' Journal of Applied Physics, Vol. 76, pp. 2742-2747 https://doi.org/10.1063/1.357578
  11. Krausz, A. S. and Krausz, K., 1996, 'Unified Constitutive Laws of Plastic Deformation,' Academic Press, San Diego
  12. Krempl, E. and Ho, K., 2000, 'An Overstress Model for Solid Polymer Deformation Behavior Applied to Nylon 66,' Time Dependent and Nonlinear Effects in Polymers and Composites, ASTM STP 1357, American Society for Testing and Materials, pp. 118-137
  13. Krempl, E. and Ho, K., 2001, 'The Overstress Model Applied to Normal and Pathological Behavior of Some Engineering Alloys,' IUTAM Symposium on Creep in Structures, S. Murakami and N. Ohno Editors, Kluwer Academic Publishers, pp. 361-373
  14. Kwangsoo Ho, 2002, 'A Generalized Viscoplasticity Theory Based on Overstress,' Trans. of the KSME(A), Vol. 26, No. 10, pp. 1953-1960
  15. Penning, P., 1972, 'Mathematics of the Portevin LeChatelier Effect,' Acta Metallurgica, Vol. 22, pp. 1169-1175 https://doi.org/10.1016/0001-6160(72)90165-4
  16. Miller, A.K. and Sherby, O.D., 1978, 'A Simplified Phenomenological Model for Non-Elastic Deformation: Prediction of Pure Aluminum Behavior and Incorporation of Solute Strengthening Effects,' Acta Metallurgica, Vol. 26, pp. 289-304 https://doi.org/10.1016/0001-6160(78)90129-3
  17. Mulford, R.A. and Kocks, U.F., 1979, 'New Observation on the Mechanisms of Dynamic Strain Aging and of Jerky Flow,' Acta Metallurgica, Vol. 27, pp. 1125-1134 https://doi.org/10.1016/0001-6160(79)90130-5
  18. Kalk, A. and Schwink, CH., 1992, 'On Sequences of Alternate Stable and Unstable Regions Along Tensile Deformation Curves,' Physica Status Solidi, Vol. 172, pp. 133-144 https://doi.org/10.1002/pssb.2221720114