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Mechanics of Time-Dependent Materials

, Volume 9, Issue 4, pp 57–78 | Cite as

Methodology for Parameter Identification in Nonlinear Viscoelastic Material Model

  • Lars-Olof Nordin
  • Janis Varna
Article

Abstract

Two methodologies for identification of material functions in Schapery's nonlinear viscoelastic material model are compared in context to their ability to deal with deviations from Heaviside stepwise load application and unloading in real test conditions where the time intervals for load increase to plateau value and to unloading to zero are finite. In the first method the description of the whole loading, creep, unloading and recovery process is given by one-step load application and one-step unloading whereas in the second method the load increase and decrease intervals are approximated by two-step load application with 0.5 of the load applied in the increase region. Vinyl ester with known viscoelastic properties and incremental form of Schapery's constitutive equation is used to simulate “experimental data” for several length of load application and unloading. The two data reduction methodologies are applied to these “data” and the accuracy of identified material functions is compared with the true values (input data).

Keywords

creep strain recovery ramp loading incremental Vinyl ester nonlinear viscoelasticity 

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References

  1. Guedes, R.M., Marques, A.T., and Cardon, A., ‘Analytical and experimental evaluation of nonlinear viscoelastic- viscoplastic composite laminates under creep, creep-recovery, relaxation and ramp loading’, Mechanics of Time-Dependent Materials 2, 1998, 113–128.CrossRefGoogle Scholar
  2. Knauss, W.G. and Emri, I., ‘Non-linear viscoelasticity based on free volume considerations’, Computers and Structures 13, 1981, 123–128.CrossRefzbMATHGoogle Scholar
  3. Lou, Y.C. and Schapery, R.A., ‘Viscoelastic characterization of a nonlinear fiber-reinforced plastic’, J. of Composite Materials 5, 1971, 208–234.CrossRefGoogle Scholar
  4. Megnis, M. and Varna, J., ‘Nonlinear Viscoelastic, viscoplastic characterization of unidirectional GF/EP composite’, Mechanics of Time-Dependent Materials 7, 2003, 269–290.CrossRefADSGoogle Scholar
  5. Megnis, M. and Varna, J., ‘Micromechanics based modeling of non-linear viscoplastic response of unidirectional composite’, Composite Science and Technology 63, 2003, 19–31.CrossRefGoogle Scholar
  6. Nordin, L-O., Marklund, E., Stahlberg, D. and Varna, J., ‘Mechanical response of thermoset polymers under high compressive loads, 2’, Macromolecular Materials & Engineering 290, 2005.Google Scholar
  7. Popelar, C.F. and Liechti, K.M., ‘Multiaxial nonlinear viscoelastic characterization and modeling of a structural adhesive’, J. of Engineering Materials Technology 119, 1997, 205–210.CrossRefGoogle Scholar
  8. Schapery, R.A., ‘Nonlinear viscoelastic and viscoplastic constitutive equations based on thermodynamics’, Mechanics of Time-Dependent Materials 1, 1997, 209–240.CrossRefGoogle Scholar
  9. Stahlberg, D., Nordin, L-O., Varna, J., and Johansson, M., ‘Mechanical response of thermoset polymers under high compressive loads, 1’, Macromolecular Materials & Engineering 290, 2005, 1063–1072.Google Scholar

Copyright information

© Springer Science+Business Media, Inc. 2006

Authors and Affiliations

  1. 1.Lulea University of TechnologyLuleaSweden

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