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A numerical approach for obtaining nonlinear viscoelasticity parameters of polymeric materials and composites
Author(s) -
Augl Joseph M.,
Land David J.
Publication year - 1985
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1985.070301101
Subject(s) - nonlinear system , viscoelasticity , materials science , non linear least squares , power (physics) , creep , mathematics , iterative method , sensitivity (control systems) , power law , curve fitting , algorithm , composite material , thermodynamics , estimation theory , physics , statistics , quantum mechanics , electronic engineering , engineering
A least‐squares fitting procedure is developed for application to determine the parameters of the power law for nonlinear creep and recovery behavior of polymeric materials. The nonlinear power law, developed by Schapery from thermodynamic principles, is linearized, and an iterative approach is used to determine the desired parameters. The iteration is stopped after the standard deviation of the calculated points with respect to the fitted points reaches a minimum value. The purpose of this method is to avoid the inherent ambiguities present in the more familiar graphical fitting procedure. In order to study the sensitivity and limitations of an experimental approach for determining the viscoelastic parameters, sets of artificial experimental data points were generated for use as a control. These points were obtained by varying the theoretical functional values with normally‐distributed random numbers within a preset error band.