Advertisement

Back Stress in Modeling the Response of PEEK and PC

  • Wenlong Li
  • George Gazonas
  • Eric N. Brown
  • Philip J. Rae
  • Mehrdad Negahban
Conference paper
Part of the Conference Proceedings of the Society for Experimental Mechanics Series book series (CPSEMS)

Abstract

With the development of new methods for the characterization of equilibrium stress through cyclic loading, it is now possible to follow the evolution of back stress during the nonlinear deformation of polymers. Experiments on PEEK and PC below the glass-transition temperature indicate a back stress that may evolve with plastic deformation, and which is substantially different from that seen during the response in the rubbery range. In particular, the back stress during the response of PC shows the characteristic post-yield softening, possibly indicating that the observed post-yield softening in the response comes from the back stress. This is not seen in PEEK, which also shows no substantial post-yield softening. The equilibrium stress plays a central role in modeling both the quasi-static and dynamic response of PEEK.

Keywords

Mechanical modeling Plastic flow Equilibrium stress Thermal expansion Digital image correlation 

Notes

Acknowledgement

The research was partially supported by the US Army Research Laboratory through Contract Number W911NF-11-D-0001-0094. The experiments were completed by utilizing the stress analysis facility at the University of Nebraska-Lincoln.

References

  1. 1.
    Argon, A.S., Bessonov, M.I.: Plastic flow in glassy polymers. Polym. Eng. Sci. 17, 174–182 (1977)CrossRefGoogle Scholar
  2. 2.
    Boyce, M.C., Parks, D.M., Argon, A.S.: large inelastic deformation of glassy polymers. Part I: rate dependent constitutive model. Mech. Mater. 7, 15–33 (1988)CrossRefGoogle Scholar
  3. 3.
    Arruda, E.M., Boyce, M.C.: Evolution of plastic anisotropy in amorphous polymers during finite stretch. Int. J. Plasticity 9, 697–721 (1993)CrossRefGoogle Scholar
  4. 4.
    Boyce, M.C., Arruda, E.M.: An experimental and analytical investigation of the large strain compressive and tensile response of glassy polymers. Polym. Eng. Sci. 30, 1288–1298 (1990)CrossRefGoogle Scholar
  5. 5.
    Shim, J., Dirk, M.: Rate dependent finite strain constitutive model of polyurea. Int. J. Plasticity 27, 868–886 (2011)CrossRefzbMATHGoogle Scholar
  6. 6.
    Krempl, E., Mcmahon, J.J.: Viscoplasticity based on overstress with a differential growth law for the equilibrium stress. Mech. Mater. 5, 35–48 (1986)CrossRefGoogle Scholar
  7. 7.
    Krempl, E., Bordonaro, C.: A state variable model for high strength polymer. Polym. Eng. Sci. 35, 310–316 (1995)CrossRefGoogle Scholar
  8. 8.
    Krempl, E., Khan, F.: Rate (time)-dependent deformation behavior: an overview of some properties of metals and solid polymers. Int. J. Plasticity 19, 1069–1095 (2003)CrossRefzbMATHGoogle Scholar
  9. 9.
    Krempl, E., Gleason, J.M.: Isotropic viscoplasticity theory based on overstress (VBO). The influence of the direction of the dynamic recovery term in the growth law of the equilibrium stress. Int. J. Plasticity 12, 719–735 (1996)CrossRefzbMATHGoogle Scholar
  10. 10.
    Krempl, E.: Relaxation behavior and modeling. Int. J. Plasticity 17, 1419–1436 (2001)CrossRefzbMATHGoogle Scholar
  11. 11.
    Colak, O.U.: Modeling deformation behavior of polymers with viscoplasticity theory based on overstress. Int. J. Plasticity 21, 145–160 (2005)CrossRefzbMATHGoogle Scholar
  12. 12.
    Negahban, M.: The Mechanical and Thermodynamical Theory of Plasticity. CRC Press, New York (2012)zbMATHGoogle Scholar
  13. 13.
    Li, W., Brown, E.N., Rae, P.J., Gazonas, G., Negahban, M.: Mechanical characterization and preliminary modeling of PEEK. Mech. Compos. Multi-funct. Mater. 7, 209–218 (2015)Google Scholar
  14. 14.
    Bordonaro, C., Krempl, E.: The effect of strain rate on the deformation and relaxation behavior of 6/6 nylon at room temperature. Polym. Eng. Sci. 32, 1066–1072 (1992)CrossRefGoogle Scholar
  15. 15.
    Negahban, M., Goel, A., Delabarre, P., Feng, R., Dimick, A.: Experimentally evaluating the equilibrium stress in shear of glassy polycarbonate. ASME J. Eng. Mater. Technol. 128, 537–542 (2006)CrossRefGoogle Scholar
  16. 16.
    Goel, A., Strabala, K., Negahban, M., Feng, R.: Experimentally evaluating equilibrium stress in uniaxial tests. Exp. Mech. 50, 709–716 (2010)CrossRefGoogle Scholar
  17. 17.
    Dreistadt, C., Bonnet, A.-E., Chevrier, P., Lipinski, P.: Experimental study of polycarbonate behavior during complex loadings and comparison with the Boyce, Parks and Argon model predictions. Mater. Des. 30, 3126–3140 (2009)CrossRefGoogle Scholar

Copyright information

© The Society for Experimental Mechanics, Inc. 2017

Authors and Affiliations

  • Wenlong Li
    • 1
  • George Gazonas
    • 2
  • Eric N. Brown
    • 3
  • Philip J. Rae
    • 3
  • Mehrdad Negahban
    • 1
  1. 1.Mechanical and Materials EngineeringUniversity of Nebraska-LincolnLincolnUSA
  2. 2.U.S. Army Research LaboratoryAberdeen Proving GroundAberdeenUSA
  3. 3.Los Alamos National LaboratoryLos AlamosUSA

Personalised recommendations