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

A Nonlinear Viscoelastic Model for Adipose Tissue Representing Tissue Response at a Wide Range of Strain Rates and High Strain Levels

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Hosein Naseri ◽  
Håkan Johansson ◽  
Karin Brolin
Keyword(s):  
Finite Element ◽  
Adipose Tissue ◽  
Human Body ◽  
Viscoelastic Model ◽  
Tissue Response ◽  
Strain Rates ◽  
Nonlinear Viscoelastic ◽  
Wide Range ◽  
Human Body Models ◽  
Nonlinear Viscoelastic Model

Finite element human body models (FEHBMs) are nowadays commonly used to simulate pre- and in-crash occupant response in order to develop advanced safety systems. In this study, a biofidelic model for adipose tissue is developed for this application. It is a nonlinear viscoelastic model based on the Reese et al.'s formulation. The model is formulated in a large strain framework and applied for finite element (FE) simulation of two types of experiments: rheological experiments and ramped-displacement experiments. The adipose tissue behavior in both experiments is represented well by this model. It indicates the capability of the model to be used in large deformation and wide range of strain rates for application in human body models.

scholarly journals Mechanical Behavior of Liquid Nitrile Rubber-Modified Epoxy Resin under Static and Dynamic Loadings: Experimental and Constitutive Analysis

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1565 ◽  
Author(s):  
Xiao Xu ◽  
Shiqiao Gao ◽  
Zhuocheng Ou ◽  
Haifu Ye
Keyword(s):  
Epoxy Resin ◽  
Dynamic Compression ◽  
Viscoelastic Model ◽  
Nitrile Rubber ◽  
Elastic Behavior ◽  
Model Parameters ◽  
Strain Rates ◽  
Nonlinear Viscoelastic ◽  
Wide Range ◽  
Nonlinear Viscoelastic Model

Quasi-static and dynamic compression experiments were performed to study the influence of liquid nitrile rubber (LNBR) on the mechanical properties of epoxy resin. The quasi-static experiments were conducted by an electronic universal machine under strain rates of 0.0001/s and 0.001/s, while a Split Hopkinson Pressure Bar (SHPB) system was adopted to perform the dynamic tests for strain rates up to 5600/s. The standard Zhu-Wang-Tang (ZWT) nonlinear viscoelastic model was chosen to predict the elastic behavior of LNBR/epoxy composites under a wide range of strain rates. After some necessary derivation and data fitting, a set of model parameters for the tested materials were finally obtained. Meanwhile, the incremented form of the ZWT nonlinear viscoelastic model were deduced and implemented into the user material program of LS-DYNA. A simulation-test contrast had been performed to verify the validity and feasibility of the algorithm. The results showed that the viscoelastic behavior of epoxy resin can be effectively simulated.

Viscoelastic Properties of Single Attached Cells Under Compression

2004 ◽  
Vol 127 (2) ◽  
pp. 237-243 ◽  
Author(s):  
Emiel A.G. Peeters ◽  
Cees W.J. Oomens ◽  
Carlijn V.C. Bouten ◽  
Dan L. Bader ◽  
Frank P.T. Baaijens
Keyword(s):  
Elastic Modulus ◽  
Viscoelastic Properties ◽  
Laser Scanning ◽  
Viscoelastic Model ◽  
Laser Scanning Microscopy ◽  
Confocal Laser ◽  
Nonlinear Viscoelastic ◽  
Wide Range ◽  
Dynamic Experiments ◽  
Nonlinear Viscoelastic Model

The viscoelastic properties of single, attached C2C12 myoblasts were measured using a recently developed cell loading device. The device allows global compression of an attached cell, while simultaneously measuring the associated forces. The viscoelastic properties were examined by performing a series of dynamic experiments over two frequency decades (0.1-10Hz) and at a range of axial strains (∼10-40%). Confocal laser scanning microscopy was used to visualize the cell during these experiments. To analyze the experimentally obtained force-deformation curves, a nonlinear viscoelastic model was developed. The nonlinear viscoelastic model was able to describe the complete series of dynamic experiments using only a single set of parameters, yielding an elastic modulus of 2120±900Pa for the elastic spring, an elastic modulus of 1960±1350 for the nonlinear spring, and a relaxation time constant of 0.3±0.12s. To our knowledge, it is the first time that the global viscoelastic properties of attached cells have been quantified over such a wide range of strains. Furthermore, the experiments were performed under optimal environmental conditions and the results are, therefore, believed to reflect the viscoelastic mechanical behavior of cells, such as would be present in vivo.

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

Linearization of a Viscoelastic Model for Light-Weight Embankment

2011 ◽  
Vol 324 ◽  
pp. 368-371
Author(s):  
Hayssam El Ghoche
Keyword(s):  
Viscoelastic Model ◽  
Light Weight ◽  
Specific Density ◽  
Linear Forms ◽  
Plastic Films ◽  
Nonlinear Viscoelastic ◽  
New Process ◽  
Real Behavior ◽  
Nonlinear Viscoelastic Model ◽  
Experimental And Theoretical Studies

A new process of light-weight embankment by using parallelepipedal blocks which made up of plastic films in order to obtain a density of 0.4, 0.5 or 0.6. The experimental and theoretical studies of this material enabled us to elaborate a nonlinear viscoelastic model. It shows clearly the real behavior, but it needs the identification of a great number of parameters. The purpose of this paper is to simplify the model by linearzing it. This linearization was carried out for a specific density (0.6) in two ways: - Adoption of linear forms of the elastic and delayed deformations according to the stress. - Adoption of a linear form of the elastic deformation and a constant delayed one (linear viscoelasticity). The comparison between experience and theory shows that the linear model describes the reality in a field of stresses which can reach 200 kPa.

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