Stress Relaxation in Combined Torsion-Tension

1970 ◽  
Vol 37 (1) ◽  
pp. 53-60 ◽  
Author(s):  
W. Goldberg ◽  
G. Lianis
Keyword(s):  
Stress Relaxation ◽  
Constitutive Equation ◽  
Constitutive Relation ◽  
Axial Force ◽  
Single Step ◽  
Tension Stress ◽  
Simple Material ◽  
Theoretical Predictions ◽  
Fluid Theory ◽  
Relaxation Experiments

In this paper we briefly examine the form of the isothermal constitutive relation of an isotropic simple material under stress-relaxation conditions. We then compare the predictions of the Signorini form of the Bernstein, Kearsley, Zapas elastic fluid theory and the Lianis constitutive equation for single-step stress-relaxation histories and show that they are identical. Using these theories, we develop theoretical expressions for the torque and axial force in combined torsion-tension stress relaxation. Experiments were performed on samples of an SBR polymer, and the observed response is compared with theoretical predictions.

The Effect of Overshooting the Target Strain on Estimating Viscoelastic Properties From Stress Relaxation Experiments

2004 ◽  
Vol 126 (6) ◽  
pp. 844-848 ◽  
Author(s):  
Jonathan A. Gimbel ◽  
Joseph J. Sarver ◽  
Louis J. Soslowsky
Keyword(s):  
Stress Relaxation ◽  
Single Step ◽  
Strain History ◽  
Estimation Of Parameters ◽  
Ramp Rate ◽  
Relaxation Experiment ◽  
Curve Fit ◽  
Target Strain ◽  
Linear Viscoelastic ◽  
Relaxation Experiments

Background: Tendon’s mechanical behaviors have frequently been quantified using the quasi-linear viscoelastic (QLV) model. The QLV parameters are typically estimated by fitting the model to a single-step stress relaxation experiment. Unfortunately, overshoot of the target strain occurs to some degree in most experiments. This has never been formally investigated even though failing to measure, minimize, or compensate for overshoot may cause large errors in the estimation of parameters. Therefore, the objective of this study was to investigate the effect of overshoot on the estimation of QLV parameters. Method of approach: A simulated experiment was first performed to quantify the effect of different amounts of overshoot on the estimated QLV parameters. Experimental data from tendon was then used to determine if the errors associated with overshoot could be reduced when a direct fit is used (i.e., the actual strain history was used in the curve fit). Results: We found that both the elastic and viscous QLV parameters were incorrectly estimated if overshoot was not properly accounted for in the fit. Furthermore, the errors associated with overshoot were partially reduced when overshoot was accounted for using a direct fit. Conclusions: A slow ramp rate is recommended to limit the amount of overshoot and a direct fit is recommended to limit the errors associated with overshoot, although other approaches such as adjusting the control system to limit overshoot could also be utilized.

scholarly journals A Modified Fractional Maxwell Numerical Model for Constitutive Equation of Mn-Cu Damping Alloy

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2020
Author(s):  
Baoquan Mao ◽  
Rui Zhu ◽  
Zhiqian Wang ◽  
Yuying Yang ◽  
Xiaoping Han ◽  
...  
Keyword(s):  
Constitutive Equation ◽  
Strain Rate ◽  
Constitutive Relation ◽  
Constant Strain Rate ◽  
Strain Curve ◽  
Maxwell Model ◽  
Nonlinear Viscoelastic ◽  
Fractional Maxwell Model ◽  
Hysteretic Characteristics ◽  
Nonlinear Elastic

To better describe its constitutive relation, we need a new constitutive equation for an important nonlinear elastic material, Mn-Cu damping alloy. In this work, we studied the nonlinear and hysteretic characteristics of the stress-strain curve of the M2052 alloy with the uniaxial cyclic tensile test with constant strain rate. The strain rate and amplitude correlations of M2052 resembled those of nonlinear viscoelastic material. Therefore, we created a new constitutive equation for the M2052 damping alloy by modifying the fractional Maxwell model, and we used the genetic algorithm to carry out numerical fitting with MATLAB. By comparing with the experimental data, we confirmed that the new constitutive equation could accurately depict the nonlinear constitutive relation and hysteretic property of the damping alloy. Taken together, this new constitutive equation for Mn-Cu damping alloy based on the fractional Maxwell model can serve as an effective tool for further studies of the constitutive relation of the Mn-Cu damping alloys.

On the inference of viscoelastic constants from stress relaxation experiments

2019 ◽  
Vol 24 (1) ◽  
pp. 1-24 ◽  
Author(s):  
Kumar Vemaganti ◽  
Sandeep Madireddy ◽  
Sayali Kedari
Keyword(s):  
Stress Relaxation ◽  
Relaxation Experiments ◽  
Viscoelastic Constants

Study on Nonlinear Viscoelastic Properties of Asphalt Mixture Based on Stress Relaxation Test

2014 ◽  
Vol 563 ◽  
pp. 48-52
Author(s):  
Lei Chen ◽  
Zhi Xin Yu ◽  
Wei Ping Cui ◽  
Li Juan Qin
Keyword(s):  
Stress Relaxation ◽  
Asphalt Mixture ◽  
Viscoelastic Behavior ◽  
Exponential Model ◽  
Relaxation Test ◽  
Asphalt Binders ◽  
Stress Relaxation Test ◽  
Nonlinear Viscoelastic ◽  
Low Temperature Cracking ◽  
Relaxation Experiments

Development of normal stress in the direction perpendicular to the asphalt mixture is an important feature of the nonlinear viscoelastic behavior of asphalt binders. In this paper, this phenomenon was studied with the help of stress-relaxation experiments in torsion.  Results indicate that stress relaxation test by controlling strain could be used to evaluate the stress relaxation ability of asphalt mixture. With the aging degree of asphalt mixtures increased, the low temperature cracking resistance got worse; the higher the temperature is, the faster the stress relaxed; the smaller the initial strain, the worse the stress relaxation ability also. The viscoelasticity of asphalt mixture could be simulated by exponential model fractional and the experiments well supported the modeling results.

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