A Kinetics Approach to the Derivation and Measurement of the Constitutive Equations of Time-Dependent Deformation

2009 ◽  
pp. 284-284-14
Author(s):  
AS Krausz ◽  
B Faucher
Keyword(s):  
Constitutive Equations ◽  
Time Dependent

Thermoelastic Constitutive Equations for Chemically Hardening Materials

1974 ◽  
Vol 41 (3) ◽  
pp. 652-657 ◽  
Author(s):  
Bernard W. Shaffer ◽  
Myron Levitsky
Keyword(s):  
Bulk Modulus ◽  
Strain Rate ◽  
Chemical Reaction ◽  
Constitutive Equations ◽  
Strain Energy ◽  
Elastic Solid ◽  
Time Dependent ◽  
Component Model ◽  
Two Component ◽  
Potential Applications

Thermoelastic constitutive equations are derived for a material undergoing solidification or hardening as the result of a chemical reaction. The derivation is based upon a two component model whose composition is determined by the degree of hardening, and makes use of strain-energy considerations. Constitutive equations take the form of stress rate-strain rate relations, in which the coefficients are time-dependent functions of the composition. Specific results are developed for the case of a material of constant bulk modulus which undergoes a transition from an initial liquidlike state into an isotropic elastic solid. Potential applications are discussed.

Nonlinear Viscoelastic Constitutive Equations for Composites Based on Work Potentials

1994 ◽  
Vol 47 (6S) ◽  
pp. S269-S275 ◽  
Author(s):  
R. A. Schapery
Keyword(s):  
Constitutive Equations ◽  
Viscoelastic Behavior ◽  
Polymeric Materials ◽  
Time Dependent ◽  
Inelastic Behavior ◽  
Nonlinear Viscoelastic ◽  
Viscoelastic Effects ◽  
Residual Strains ◽  
Viscoelastic Composites ◽  
Independent Behavior

Constitutive equations for nonlinear viscoelastic composites are discussed. The effects of time-independent inelastic behavior, microcracking and time-dependent residual strains are considered along with the viscoelastic effects that are traditionally associated with the behavior of monolithic and reinforced polymeric materials. Time-independent behavior is discussed first, in which the experimentally observed insensitivity of mechanical work to deformation or load paths is used as the basis for a simplified constitutive model. This representation is then modified to account for time- or rate-effects due to microcrack-like evolution laws. Effects due to broad spectrum nonlinear, viscoelastic behavior of the polymer matrix are reviewed and then used in a generalized constitutive equation with both time-independent and time-dependent effects. Emphasis of this paper is on a thermodynamically-based phenomenological description of deformation response and the use of simplifications based on experimental observations. However, there is a limited discussion of physical mechanisms for nonlinear time-dependent behavior.

Creep and Plastic Strains of 304 Stainless Steel at 593°C Under Step Stress Changes, Considering Aging

1982 ◽  
Vol 49 (2) ◽  
pp. 297-304 ◽  
Author(s):  
U. W. Cho ◽  
W. N. Findley
Keyword(s):  
Stainless Steel ◽  
Constitutive Equations ◽  
Time Dependent ◽  
304 Stainless Steel ◽  
Flow Rule ◽  
Strain Component ◽  
Plastic Strains ◽  
Aging Effects ◽  
Stress Changes ◽  
Step Down

Nonlinear constitutive equations for varying stress histories are developed and used to predict the creep behavior of 304 stainless steel at 593°C (1100°F) under variable tension or torsion stresses including reloading, complete unloading, step-up, and step-down stress changes. The strain in the constitutive equations (a viscous-viscoelastic model) consists of: linear elastic, time-independent plastic, time-dependent-recoverable viscoelastic, and time-dependent-nonrecoverable viscous components. For variable stressing, the modified superposition principle, derived from the multiple integral representation, and the strain hardening theory were used to represent the recoverable and nonrecoverable components, respectively, of the time-dependent strain. Time-independent plastic strains were described by a flow rule of similar form to that for nonrecoverable, time-dependent strains. The material constants of the theory were determined from constant stress creep and creep recovery data. Considerable aging effects were found and the effects on the strain components were incorporated in each strain predicted by the theory. Some modifications of the theory for the viscoelastic strain component under step-down stress changes were made to improve the predictions. The final predictions combining the foregoing features made satisfactory agreements with the experimental creep data under step stress changes.

Postsurcharge secondary compression equation for clays

1988 ◽  
Vol 25 (3) ◽  
pp. 594-599 ◽  
Author(s):  
Eulalio Juárez-Badillo
Keyword(s):  
Key Words ◽  
Mexico City ◽  
Volume Change ◽  
Constitutive Equations ◽  
Time Dependent ◽  
Practical Application ◽  
Secondary Compression ◽  
General Time

A general time – volume change equation for soils is used to describe the initial swelling and further secondary compression of clay samples when surcharges are used. The procedure is illustrated by a practical application to México City clay. Key words: clay, secondary compression, secondary consolidation, postsurcharge, time-dependent compression, constitutive equations.

Creep of 2618 Aluminum Under Step Stress Changes Predicted by a Viscous-Viscoelastic Model

1980 ◽  
Vol 47 (1) ◽  
pp. 21-26 ◽  
Author(s):  
J. S. Lai ◽  
W. N. Findley
Keyword(s):  
Constitutive Equations ◽  
Superposition Principle ◽  
Viscoelastic Model ◽  
Multiple Integral ◽  
Constant Stress ◽  
Time Dependent ◽  
Stress Tests ◽  
Linear Elastic ◽  
Stress Changes ◽  
Dependent Strain

Nonlinear constitutive equations are developed and used to predict from constant stress data the creep behavior of 2618 Aluminum at 200°C (392°F) for tension or torsion stresses under varying stress history including stepup, stepdown, and reloading stress changes. The strain in the constitutive equation employed includes the following components: linear elastic, time-independent plastic, nonlinear time-dependent recoverable (viscoelastic), nonlinear time-dependent nonrecoverable (viscous) positive, and nonlinear time-dependent nonrecoverable (viscous) negative. The modified superposition principle, derived from the multiple integral representation, and strain-hardening theory were used to represent the recoverable and nonrecoverable components, respectively, of the time-dependent strain in the constitutive equations. Excellent-to-fair agreement was obtained between the experimentally measured data and the predictions based on data from constant-stress tests using the constitutive equations as modified.

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