On the determination of the relaxation modulus of PP compounds from arbitrary strain histories
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Advanced evaluation methods for the determination of linear viscoelastic material functions have been developed already forty years ago, but it is still common practice to use the so-called ten-times rule. The rule is that a sufficiently long time needs to pass after a constant load or strain is applied so that the material response is close to the response of step excitation. A substantial amount of experimental data in the short-term range has to be discarded to obtain valid results. Renewed attention has been given to improving this situation during the last few years. In this paper, the application of modern evaluation techniques to the determination of the relaxation modulus of isotropic homogeneous linear viscoelastic materials is presented. A new method that is applicable to general strain histories is introduced and applied to different loading types.
KeywordsViscoelastic behavior Ramp loading Relaxation test Creep test Relaxation modulus
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- Jerabek, M., Tscharnuter, D., Major, Z., Ravi-Chandar, K., Lang, R.W.: Relaxation behavior of neat and particulate filled polypropylene in uniaxial and multiaxial compression. Mech. Time-Depend. Mater. 14(47), 68 (2010d) Google Scholar
- Press, W.H., Teukolsky, S.A.: Simulated annealing optimization over continuous spaces. Comput. Phys. 5(4), 426 (1991) Google Scholar
- Press, W.H., Flannery, B.P., Teukolsky, S.A., Vetterling, W.T.: Numerical Recipes in C: The Art of Scientific Computing. Cambridge University Press, Cambridge (1992) Google Scholar
- Tscharnuter, D., Jerabek, M., Major, Z., Lang, R.W.: Time-dependent poisson’s ratio of polypropylene compounds for various strain histories. Mech. Time-Depend. Mater. (2010, submitted) Google Scholar
- Zapas, L.J., Craft, T.: Correlation of large longitudinal deformations with different strain histories. J. Res. Natl. Bur. Stand. A 69(6), 541–546 (1965) Google Scholar