Modeling of Elasticity and Damping for Filled Elastomers
Author
Summary, in English
Elasticity and damping are significant properties of rubber, taken advantage of in engineering applications. It is therefore important that the constitutive model accurately captures these aspects of the mechanical behavior.
In the first part of the thesis a description of theory and experiments for determination of hyperelastic parameters required for finite element analysis is provided. Test specimens and corresponding stress-strain relations for calibration of the hyperelastic models are discussed. Mechanical conditioning procedures are compared and fitting of the models are discussed, with special emphasis on a ``cubic I1'' model proposed by O.H. Yeoh. A strain energy plot to check the quality of the fitted model is presented, which reveals whether the model is valid for use in finite element analysis. The accuracy of existing test specimens, and a new axisymmetric combined compression and tension specimen proposed here, are investigated by finite element analysis. A modified hardness test for evaluation of hyperelastic constants is presented and evaluated by finite element analysis. Moreover, a method for contact-free strain measurement for evaluation of surface strain fields is presented. Experimental deformation gradients can also be obtained by this method.
The second part of the thesis concerns modeling of dynamic material properties of filled rubbers. Experiments show that constitutive models available in commercial finite element codes are not able to model the behavior of filled rubber vulcanizates in dynamic applications. One-dimensional models are used to examine the mechanisms of damping in these rubbers. The ability of the models to capture the frequency and amplitude dependence of the dynamic modulus and equivalent phase angle is investigated. The microstructure and the experimental results support a model with nonlinear elastic, viscous (rate-dependent) and frictional (rate-independent) elements connected in parallel. A generalization of this one-dimensional viscoplastic model to multiaxial and large strains is proposed and evaluated in simple shear and uniaxial stress.
In the first part of the thesis a description of theory and experiments for determination of hyperelastic parameters required for finite element analysis is provided. Test specimens and corresponding stress-strain relations for calibration of the hyperelastic models are discussed. Mechanical conditioning procedures are compared and fitting of the models are discussed, with special emphasis on a ``cubic I1'' model proposed by O.H. Yeoh. A strain energy plot to check the quality of the fitted model is presented, which reveals whether the model is valid for use in finite element analysis. The accuracy of existing test specimens, and a new axisymmetric combined compression and tension specimen proposed here, are investigated by finite element analysis. A modified hardness test for evaluation of hyperelastic constants is presented and evaluated by finite element analysis. Moreover, a method for contact-free strain measurement for evaluation of surface strain fields is presented. Experimental deformation gradients can also be obtained by this method.
The second part of the thesis concerns modeling of dynamic material properties of filled rubbers. Experiments show that constitutive models available in commercial finite element codes are not able to model the behavior of filled rubber vulcanizates in dynamic applications. One-dimensional models are used to examine the mechanisms of damping in these rubbers. The ability of the models to capture the frequency and amplitude dependence of the dynamic modulus and equivalent phase angle is investigated. The microstructure and the experimental results support a model with nonlinear elastic, viscous (rate-dependent) and frictional (rate-independent) elements connected in parallel. A generalization of this one-dimensional viscoplastic model to multiaxial and large strains is proposed and evaluated in simple shear and uniaxial stress.
Department/s
Publishing year
1997
Language
English
Publication/Series
TVSM-1000
Issue
TVSM-1009
Full text
- Available as PDF - 16 MB
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Document type
Dissertation
Publisher
Structural Mechanics, Lund University
Topic
- Mechanical Engineering
Keywords
- rheological models
- contact-free strain measurement
- modified hardness test
- solid dumbbell test specimen
- mechanical conditioning
- strain energy plot
- hyperelasticity
- carbon-black-filled rubbers
- amplitude dependence
- multiaxial viscoplastic model
- Building construction
- Byggnadsteknik
Status
Published
Supervisor
- [unknown] [unknown]
ISBN/ISSN/Other
- LUTVDG/(TVSM-1009)/1-222/(1997)
Defence date
10 April 1997
Defence time
10:15
Defence place
John Ericssons vag 1, V:C
Opponent
- David Hibbitt (Professor)