Determination of the relaxation spectrum from oscillatory shear data
作者:
Nese Orbey,
John M. Dealy,
期刊:
Journal of Rheology
(AIP Available online 1991)
卷期:
Volume 35,
issue 6
页码: 1035-1049
ISSN:0148-6055
年代: 1991
DOI:10.1122/1.550164
出版商: The Society of Rheology
关键词: Relaxation spectrum;Relaxation modulus;Viscoelasticity;Oscillatory shear;Dynamic measurements;RELAXATION;DATA ANALYSIS;FLUID MECHANICS;REGRESSION ANALYSIS;VISCOELASTICITY
数据来源: AIP
摘要:
In order to use either a linear or nonlinear model of viscoelasticity to calculate the stress response of a material to various deformations, it is usually necessary to have available an explicit equation for the linear relaxation modulusG(t). The most popular procedure is to use the data from a small‐amplitude oscillatory shear experiment to determine the parameters of a generalized Maxwell model. However, this is an ill‐posed problem and is not at all a straightforward curve‐fitting operation. We compare three procedures for determining a set of relaxation times and discrete moduli that can then be used as empirical fitting parameters in fluid mechanics computations. These are linear regression, with and without regularization, and nonlinear regression. Nonlinear regression is found to give a good fit of the data with a minimum number of parameters.
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