scholarly journals Uniaxial stress relaxation of softened celluloid. Applicability of nonlinear viscoelastic model to large strain.

1987 ◽  
Vol 36 (407) ◽  
pp. 861-865
Author(s):  
Hisaaki TOBUSHI
Keyword(s):  
Stress Relaxation ◽  
Large Strain ◽  
Viscoelastic Model ◽  
Uniaxial Stress ◽  
Nonlinear Viscoelastic ◽  
Nonlinear Viscoelastic Model

Tensile Property Test Analysis of Double Protein Modified Fiber

2012 ◽  
Vol 535-537 ◽  
pp. 1433-1436
Author(s):  
Jin Zhong Zhu ◽  
Shi Hui Wang ◽  
Jun Rui Hu ◽  
Yun Li
Keyword(s):  
Stress Relaxation ◽  
Soybean Protein ◽  
Viscoelastic Model ◽  
Test Analysis ◽  
Elongation At Break ◽  
Nonlinear Viscoelastic ◽  
Initial Modulus ◽  
Protein Fiber ◽  
Mechanical Models ◽  
Nonlinear Viscoelastic Model

In order to study the tensile mechanical properties of the double protein modified fiber. Tensile breaking property and stress relaxation were analyzed and proper mechanical models were selected for fitting. The analysis shows that: in dry and wet, the straight tensile breaking tenacity of the double protein modified fiber is weaker than that of the modified soybean protein fiber, the elongation at break and initial modulus are near to those of the modified soybean protein fiber, the breaking tenacity of the double protein modified fiber increases slightly when wet while the elongation at break and initial modulus decline a little. In knotted and looped, the double protein modified fiber’s tensile breaking tenacity is weaker than that of the modified soybean protein and its tensile breaking strength and elongation at break decrease differently. The fitting reveals that the four element nonlinear viscoelastic model is the best to describe straight tensile. The two optimal models for knotted and looped tensile are the four element nonlinear viscoelastic model and the Improved Zurek model. In addition, the six element viscoelastic plasticity model is appropriate to simulate stress relaxation.

A Nonlinear Viscoelastic Model for the Relaxation Behavior of Tendon

2012 ◽  
Author(s):  
Frances M. Davis ◽  
Raffaella De Vita
Keyword(s):  
Stress Relaxation ◽  
Relaxation Function ◽  
Viscoelastic Model ◽  
Viscoelastic Behavior ◽  
Relaxation Behavior ◽  
Successful Model ◽  
Viscoelastic Models ◽  
Nonlinear Viscoelastic ◽  
Linear Viscoelastic ◽  
Nonlinear Viscoelastic Model

Tendons are viscoelastic materials which undergo stress relaxation when held at a constant strain. The most successful model used to describe the viscoelastic behavior of tendons is the quasi-linear viscoelastic (QLV) model [1]. In the QLV model, the relaxation function is assumed to be a separable function of time and strain. Recently, this assumption has been shown to be invalid for tendons [2] thus suggesting the need for new nonlinear viscoelastic models.

On the Prediction of Stress Relaxation From Known Creep of Nonlinear Materials

1997 ◽  
Vol 119 (2) ◽  
pp. 121-124 ◽  
Author(s):  
D. Touati ◽  
G. Cederbaum
Keyword(s):  
Stress Relaxation ◽  
Viscoelastic Model ◽  
Creep Model ◽  
Nonlinear Creep ◽  
Nonlinear Viscoelastic ◽  
Calculated Stress ◽  
Nonlinear Stress ◽  
Nonlinear Viscoelastic Materials ◽  
Nonlinear Viscoelastic Model ◽  
Relaxation Curves

A method to predict the nonlinear relaxation behavior from creep experiments of nonlinear viscoelastic materials is presented. It is shown that for given nonlinear creep properties, and creep compliance represented by the Prony series, the Schapery creep model can be transformed into a set of first order nonlinear equations. The solution of these equations enables the obtaining of the nonlinear stress relaxation curves. The strain-dependent constitutive equation can then be constructed for a given nonlinear viscoelastic model, as needed for engineering applications. A comparison example of the calculated stress relaxation curves, with test data for polyurethane demonstrates the very good accuracy of the proposed method.

Free volume based nonlinear viscoelastic model for polyurea over a wide range of strain rates and temperatures

2021 ◽  
Vol 152 ◽  
pp. 103650
Author(s):  
Chencheng Gong ◽  
Yan Chen ◽  
Ting Li ◽  
Zhanli Liu ◽  
Zhuo Zhuang ◽  
...  
Keyword(s):  
Free Volume ◽  
Viscoelastic Model ◽  
Strain Rates ◽  
Nonlinear Viscoelastic ◽  
Wide Range ◽  
Nonlinear Viscoelastic Model

Identification of Nonlinear Viscoelastic Models of Flexible Polyurethane Foam From Uniaxial Compression Data

2016 ◽  
Vol 138 (2) ◽  
Author(s):  
Yousof Azizi ◽  
Patricia Davies ◽  
Anil K. Bajaj
Keyword(s):  
Uniaxial Compression ◽  
Viscoelastic Model ◽  
Viscoelastic Behavior ◽  
Model Parameters ◽  
Viscoelastic Models ◽  
Nonlinear Viscoelastic ◽  
Compression Data ◽  
Computationally Intensive ◽  
Nonlinear Viscoelastic Model ◽  
Flexible Polyurethane

Flexible polyethylene foam is used in many engineering applications. It exhibits nonlinear and viscoelastic behavior which makes it difficult to model. To date, several models have been developed to characterize the complex behavior of foams. These attempts include the computationally intensive microstructural models to continuum models that capture the macroscale behavior of the foam materials. In this research, a nonlinear viscoelastic model, which is an extension to previously developed models, is proposed and its ability to capture foam response in uniaxial compression is investigated. It is hypothesized that total stress can be decomposed into the sum of a nonlinear elastic component, modeled by a higher-order polynomial, and a nonlinear hereditary type viscoelastic component. System identification procedures were developed to estimate the model parameters using uniaxial cyclic compression data from experiments conducted at six different rates. The estimated model parameters for individual tests were used to develop a model with parameters that are a function of strain rates. The parameter estimation technique was modified to also develop a comprehensive model which captures the uniaxial behavior of all six tests. The performance of this model was compared to that of other nonlinear viscoelastic models.

On the Nonlinear Viscoelastic Behaviour of the PVC-Coated Fabric

2010 ◽  
Vol 160-162 ◽  
pp. 1476-1481 ◽  
Author(s):  
Wu Lian Zhang ◽  
Xin Ding ◽  
Xu Dong Yang
Keyword(s):  
Viscoelastic Model ◽  
Constitutive Relationship ◽  
Viscoelastic Behaviour ◽  
Viscoelastic Response ◽  
Nonlinear Parameters ◽  
Creep And Recovery ◽  
Nonlinear Viscoelastic ◽  
Coated Fabric ◽  
Nonlinear Viscoelastic Model

The nonlinear viscoelastic response of a PVC-Coated Fabric has been studied. For the needs of the present study, creep and recovery tests in tension of both the warp and the weft directions at the different stress levels were executed while measurements were made of the creep and recovery strain response of the system. For the description of the viscoelastic behaviour of the material, Schapery’s nonlinear viscoelastic model was used. For the description of the nonlinear viscoelastic response and the determination of the nonlinear parameters, a method by using a combination of analytical formulations and numerical procedures based on a modified version of Schapery’s constitutive relationship where an instantaneous plastic and a transient plastic terms were added, has been developed. The method has been successfully applied to the current tests.

scholarly journals Delayed electromechanical instability of a viscoelastic dielectric elastomer balloon

2019 ◽  
Vol 475 (2229) ◽  
pp. 20190316 ◽  
Author(s):  
Xiongfei Lv ◽  
Liwu Liu ◽  
Jinsong Leng ◽  
Yanju Liu ◽  
Shengqiang Cai
Keyword(s):  
Hoop Stress ◽  
Mechanical Load ◽  
Viscoelastic Model ◽  
Dielectric Elastomer ◽  
Time Dependent ◽  
Convex Shape ◽  
Nonlinear Viscoelastic ◽  
Electromechanical Instability ◽  
Electromechanical Loading ◽  
Nonlinear Viscoelastic Model

When a dielectric elastomer (DE) balloon is subjected to electromechanical loading, instability may happen. In recent experiments, it has been shown that the instability configuration of a DE balloon under electromechanical loading can be very different from that only subjected to mechanical load. It has also been observed in the experiments that the electromechanical instability phenomena of a DE balloon can be highly time-dependent. In this article, we adopt a nonlinear viscoelastic model for the DE membrane to investigate the time-dependent electromechanical instability of a DE balloon. Using the model, we show that under a constant electromechanical loading, a DE balloon may gradually evolve from a convex shape to a non-convex shape with bulging out in the centre, and compressive hoop stress can also gradually develop the balloon, resulting in wrinkles as observed in the experiments. We have further shown that the snap-through instability phenomenon of the DE balloon also greatly depends on the ramping rate of the applied voltage.

A nonlinear viscoelastic model for polymer solutions and melts—II

1968 ◽  
Vol 23 (8) ◽  
pp. 901-911 ◽  
Author(s):  
Pierre J. Carreau ◽  
Ian F. MacDonald ◽  
R.Byron Bird
Keyword(s):  
Polymer Solutions ◽  
Viscoelastic Model ◽  
Nonlinear Viscoelastic ◽  
Nonlinear Viscoelastic Model
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