Experimental and modeling approaches of MR behaviors under large step strains

W. H. Li, H. Du, G. Chen, N. Q. Guo

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5 Citations (Scopus)


Rheological properties of MR fluids under large step strain shear are presented in this paper. The experiments were carried out using a rheometer with parallel-plate geometry. Under the large step strain shear, MR fluids behave as nonlinear viscoelastic properties, where the stress relaxation modulus, G (t, γ), shows a decreasing trend with step strain. The experimental results indicate that G(t, γ) obeys time-strain separability. Thus, a mathematical form based on finite exponential serials is proposed to predict MR behavior. In this model, G(t, γ) is represented as the product of a linear stress relaxation, G(t), and the damping function, h(γ), i.e. G (t, γ) = G(t) h(γ). G(t) is simply represented as a three-parameter exponential serial and h(γ) has a sigmoidal form with two parameters. The parameters are identified by adopting an efficient optimization method proposed by Stango et al. The comparison between the experimental results and the model-predicted values indicates that this mathematical model can accurately predict MR behavior.

Original languageEnglish
Pages (from-to)251-257
Number of pages7
JournalMaterials Science and Engineering A: Structural Materials: Properties, Microstructure and Processing
Issue number1-2
Publication statusPublished - 15 Jan 2003
Externally publishedYes


  • Damping function
  • MR fluids
  • Step strain
  • Stress relaxation modulus

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