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Constitutive Modeling (constitutive + modeling)

Distribution by Scientific Domains

Polymers and Materials Science	75%

Selected Abstracts

Constitutive modeling for intercalated PMMA/clay nanocomposite foams

POLYMER ENGINEERING & SCIENCE, Issue 12 2006
Choonghee Jo
A constitutive model for tensile behavior of PMMA/clay nanocomposite foams was developed in this study. The elastic modulus of the nanocomposites is affected by the form of clays embedded in the polymer matrix. The reinforcing effect by intercalation of the clays and the detrimental effect by clay agglomeration were considered for the determination of the elastic modulus of the nanocomposites. A viscoelastic model was adapted for the tensile behavior of the material. The developed constitutive equation is expressed in terms of clay morphology and material properties. The aspect ratio of clays and the expansion of clay layer spacing in the intercalated clay clusters were proved to play a vital role in the reinforcing mechanism. For the verification of the constitutive model, Poly(methyl-methacrylate) (PMMA)/clay nanocomposite foams were manufactured by batch process method and their uniaxial tensile test results were compared with theoretical predictions. Compared with the experimental results, the proposed constitutive equation showed agreement with the experimental test results. POLYM. ENG. SCI. 46:1787,1796, 2006. © 2006 Society of Plastics Engineers. [source]

Modeling the Relaxation Mechanisms of Amorphous Shape Memory Polymers

ADVANCED MATERIALS, Issue 31 2010
Thao. D. Nguyen
Abstract In this progress report, we review two common approaches to constitutive modeling of thermally activated shape memory polymers, then focus on a recent thermoviscoelastic model that incorporates the time-dependent effects of structural and stress relaxation mechanisms of amorphous networks. An extension of the model is presented that incorporates the effects of multiple discrete structural and stress relaxation processes to more accurately describe the time-dependent behavior. In addition, a procedure is developed to determine the model parameters from standard thermomechanical experiments. The thermoviscoelastic model was applied to simulate the unconstrained recovery response of a family of (meth)acrylate-based networks with different weight fractions of the crosslinking agent. Results showed significant improvement in predicting the temperature-dependent strain recovery response. [source]

Effects of loading rate on viscoplastic properties of polymer geosynthetics and its constitutive modeling

POLYMER ENGINEERING & SCIENCE, Issue 3 2010
Fang-Le Peng
On the basis of the special tensile test results under various loading histories, the rate-dependent behaviors of three polymer geosynthetics due to their viscous properties have been investigated. All the investigated polymer geosynthetics show significant loading rate effects, creep deformation, and stress relaxation. Except for the polyester geogrid showing the combined viscosity, all the investigated polymer geosynthetics exhibit the isotach viscosity. An elasto-viscoplastic constitutive model described in a nonlinear three-component model framework is developed to simulate the rate-dependent behaviors of polymer geosynthetics. The developed constitutive model is verified by comparing its simulated results with the experimental data of polymer geosynthetics presented in this study and those available from the literature. The comparison indicates that the developed model can reasonably interpret the rate-dependent behaviors of polymer geosynthetics under arbitrary loading histories, including the step-changed strain rate loading, creep, and stress relaxation applied during otherwise monotonic loading (ML). POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers [source]

A New Micromechanically Based Approach for the Elastic Response of Rubber,like Materials at Large Strains

PROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2003
Serdar Göktepe M. Sc.
The approach models the elasticity of a rubber,like materials based on micro,structure that can be symbolized by a micro,sphere. The proposed model incorporates both non,a.ne deformation of unconstrained chains and superimposed constraint e.ects of tube,like topological formations in a consistent manner. Framework of the constitutive modeling and numerical examples illustrating the excellent predictive capacity of the model are presented. [source]