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Effects of temperature and strain rate on the tensile behavior of unfilled and talc‐filled polypropylene. Part II: Constitutive equation
Author(s) -
Zhou Yuanxin,
Mallick P. K.
Publication year - 2002
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.11132
Subject(s) - materials science , composite material , polypropylene , strain rate , talc , strain hardening exponent , constitutive equation , ultimate tensile strength , flow stress , exponent , softening , thermodynamics , finite element method , physics , linguistics , philosophy
Based on the experimental results presented in Part I of this research, a three parameter nonlinear constitutive model has been proposed to describe the strain rate and temperature dependent tensile behaviors of unfilled and talc‐filled polypropylene. One of the parameters is the elastic modulus. The other two parameters in this model are a strain exponent, m , and a compliance factor, β. Their relationships to strain rate and temperature are obtained from the experimental results. The simulated stress‐strain curves from the model are in good agreement with the test data. The analysis of the model shows that the strain exponent m , which controls the strain softening (or hardening) effect of the material, is not only strain rate independent, but also temperature independent. The compliance parameter, β, which controls the flow stress level of the material, on the other hand, varies with both strain rate as well as temperature. Results also show that the addition of talc filler in polypropylene reduces the strain exponent m , and increase the compliance parameter, β, which reduces the flow stress level of talc‐filled polypropylene to lower than that of unfilled polypropylene.