Application of constitutive modeling to the linear and nonlinear viscoelastic behavior of nitrile rubber /
In elastomer design, engineers tend to treat elastomers like highly elastic, low modulus materials, ignoring all viscoelastic effects. An elastomer's response to dynamic deformation is a combination of an elastic response and a viscous response with energy dissipated in each complete cycle of...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1996.
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| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=739668601&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | In elastomer design, engineers tend to treat elastomers like highly elastic, low modulus materials, ignoring all viscoelastic effects. An elastomer's response to dynamic deformation is a combination of an elastic response and a viscous response with energy dissipated in each complete cycle of deformation. Except at very small magnitudes of deformation, the material is generally nonlinear. The addition of carbon black has a profound effect at the molecular level which is manifested in the drastic change of various physical properties of the elastomer. To enable a systematic analysis of the effects of carbon black fillers on the elastomeric behavior, four different formulations with 0, 25, 50 and 75 parts per hundred parts of carbon black are chosen for this study. To check their consistency, a detailed thermal analysis was performed. It has been noted by many researchers that sinusoidal tests provide misleading information regarding materials used in nonsinusoidal periodic applications. To address this problem, various nonsinusoidal periodic strain loadings are applied and suitable modeling is employed. Mathematical models, used to quantify the stress response, should offer some physical insight into viscoelastic behavior and at the same time should be manageable for calculation purposes. The Boltzmann equation has been highly successful in modeling the linear viscoelastic behavior but has proved to be inadequate in describing the nonlinear viscoelastic behavior. A more general representation, in the form of Schapery's single integral equation for nonlinear viscoelasticity based on thermodynamic principles, has been used in this study. The verification of these equations was performed with the aid of experimental data. Reduction of relaxation modulus plots to obtain the strain dependent parameters clearly shows the distinction between filled and unfilled rubbers regarding the allotment of free energy during deformation. |
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| Item Description: | Vita. "Major Subject: Interdisciplinary Engineering". |
| Physical Description: | xiii, 174 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references: pages 145-149. |