On the Development of Creep Laws for Rubber in the Parallel Rheological Framework

2019 ◽  
Vol 47 (1) ◽  
pp. 2-30 ◽  
Author(s):  
Gautam Sagar ◽  
Dong Zheng ◽  
Anuwat Suwannachit ◽  
Maik Brinkmeier ◽  
Kristin Fietz ◽  
...  
Keyword(s):  
Complex Modulus ◽  
Dynamic Stiffness ◽  
Viscoelastic Model ◽  
American Chemical Society ◽  
Small Strain ◽  
Chemical Society ◽  
Material Behavior ◽  
Constitutive Law ◽  
Rate Dependency ◽  
Linear Viscoelastic

ABSTRACT It is widely known that filler-reinforced rubber material in tires shows a very complicated material behavior when subjected to cyclic loadings. One of the most interesting effects for rolling tires is the nonlinear rate-dependent behavior, which is implicitly linked to the amplitude dependency of dynamic stiffness (Payne effect) at a given frequency and temperature. This effect, however, cannot be described by a conventional linear viscoelastic constitutive law, e.g., the Prony series model. Several nonlinear viscoelastic material models have been proposed in the last decades. Among others, Lapczyk et al. (Lapczyk, I., Hurtado, J. A., and Govindarajan, S. M., “A Parallel Rheological Framework for Modeling Elastomers and Polymers,” 182nd Technical Meeting of the Rubber Division of the American Chemical Society, Cincinnati, Ohio, October 2012) recently proposed a quite general framework for the class of nonlinear viscoelasticity, called parallel rheological framework (PRF), which is followed by Abaqus. The model has an open option for different types of viscoelastic creep laws. In spite of the very attractive nonlinear rate-dependency, the identification of material parameters becomes a very challenging task, especially when a wide frequency and amplitude range is of interest. This contribution points out that the creep law is numerically sound if it can be degenerated to the linear viscoelastic model at a very small strain amplitude, which also significantly simplifies model calibration. More precisely, the ratio between viscoelastic stress and strain rate has to converge to a certain value, i.e., the viscosity in a linear viscoelastic case. The creep laws implemented in Abaqus are discussed in detail here, with a focus on their fitting capability. The conclusion of the investigation consequently gives us a guideline to develop a new creep law in PRF. Here, one creep law from Abaqus that meets the requirements of our guideline has been selected. A fairly good fit of the model is shown by the comparison of the simulated complex modulus in a wide frequency and amplitude range with experimental results.

Optimization of a Viscoelastic Structure: The Seat-Belt Problem

1969 ◽  
Vol 36 (3) ◽  
pp. 565-572 ◽  
Author(s):  
W. Nachbar ◽  
J. B. Schipmo¨lder
Keyword(s):  
Seat Belt ◽  
Viscoelastic Model ◽  
Small Strain ◽  
The Body ◽  
Strain Rates ◽  
Maximum Displacement ◽  
Critical Displacement ◽  
Viscoelastic Models ◽  
Maximum Value ◽  
Linear Viscoelastic

Optimization of the parameters of elementary linear viscoelastic models is considered for the design of a lap seat belt in automobiles. The vehicle is assumed to stop abruptly on impact. The parameters are optimized to allow the speed of the vehicle before impact to have the largest permissible value consistent with constraints imposed for the safety of the user of the belt. The constraints chosen here are: (a) the maximum displacement of the body after impact is equal to or less than a prescribed critical displacement; (b) the forward speed of the body at the critical displacement does not exceed a prescribed maximum value; (c) the force exerted by the belt on the body during the motion following impact does not exceed a prescribed maximum value. It is found that the optimized Kelvin-Voigt viscoelastic model is nearly 40 percent more effective than the purely elastic material. It is nearly as effective as constant deceleration. An additional and advantageous property is proposed, moreover, for belts of viscoelastic materials. This is that the material should have a relatively low spring rate at relatively small strain rates. The optimized belts for the elementary viscoelastic models are shown to be quite stiff at low strain rates, however.

An Approach to Characterize Nonlinear Viscoelastic Material Behavior Using Dynamic Mechanical Tests and Analyses

1999 ◽  
Vol 66 (4) ◽  
pp. 872-878 ◽  
Author(s):  
H. J. Golden ◽  
T. W. Strganac ◽  
R. A. Schapery
Keyword(s):  
Viscoelastic Model ◽  
Dynamic Test ◽  
Mechanical Analysis ◽  
Mechanical Tests ◽  
Material Behavior ◽  
Dynamic Mechanical ◽  
Nonlinear Characterization ◽  
Nonlinear Viscoelastic ◽  
Linear Viscoelastic ◽  
Nonlinear Viscoelastic Model

Linear viscoelastic properties may be rapidly identified using dynamic mechanical analysis methods, yet these traditional methods do not properly identify nonlinear viscoelastic response. Herein, dynamic mechanical methodologies are extended to provide an approach for nonlinear characterization. The proposed method is based on Schapery's nonlinear viscoelastic model extended to dynamic mechanical theory. The oscillatory loading during a dynamic test is addressed within the nonlinear viscoelastic model. An experimental protocol is established. Analyses and experiments are performed for the characterization of thin-film polyethylene to validate the approach.

Application of a Fractional Viscoelastic Material Model to Rubber in Comparison to a Linear Approach

2017 ◽  
Author(s):  
Michael Burgwitz ◽  
Johan Steffen Bothe ◽  
Matthias Wangenheim
Keyword(s):  
Viscoelastic Material ◽  
Thermoplastic Polyurethane ◽  
Material Model ◽  
Material Behavior ◽  
Constitutive Law ◽  
Single Degree Of Freedom ◽  
Single Degree ◽  
Linear Approach ◽  
Important Challenge ◽  
Linear Viscoelastic

The modeling of material behavior is an important challenge in structural dynamics. While some materials can be well represented by a linear constitutive law, this becomes more complex when dealing with viscoelastic components. In this paper we investigate a fractional viscoelastic material model and present our results of research, focusing on its parametrical characteristics. We compare the results to a classical linear viscoelastic standard model and highlight advantages of the particular approach: we conduct monofrequent sinusoidal excitations using a DMTA (Dynamic Mechanic Thermal Analysis) machine. We use a viscoelastic TPU (Thermoplastic Polyurethane) sheet as sample and apply varying excitation frequencies and amplitudes. In a first modeling step we reproduce the experimental results with a fractional single degree-of-freedom system with promising results.

scholarly journals Characterization of Asphalt Mixes Behaviour from Dynamic Tests and Comparison with Conventional Cyclic Tension–Compression Tests

2018 ◽  
Vol 8 (11) ◽  
pp. 2117 ◽  
Author(s):  
Jean-Claude Carret ◽  
Hervé Di Benedetto ◽  
Cédric Sauzéat
Keyword(s):  
Compression Test ◽  
Complex Modulus ◽  
Axial Stress ◽  
Viscoelastic Model ◽  
Compression Tests ◽  
Dynamic Tests ◽  
Asphalt Mixes ◽  
Cyclic Tension ◽  
Methods Of Analysis ◽  
Linear Viscoelastic

In the presented research, conventional cyclic tension–compression tests and dynamic tests were performed on two types of asphalt mixes (AM). For the tension–compression tests, the complex modulus was obtained from the measurements of the axial stress and axial strain. For the dynamic tests, an automated impact hammer equipped with a load cell and an accelerometer were used to obtain the frequency response functions (FRFs) of the specimens at different temperatures. Two methods were proposed to back-calculate the complex modulus from the FRFs at each temperature: one using the 2S2P1D (two springs, two parabolic elements and one dashpot) model and the other considering a constant complex modulus. Then, a 2S2P1D linear viscoelastic model was calibrated to simulate the global linear viscoelastic behaviour back calculated from each of the proposed methods of analysis for the dynamic tests, and obtained from the tension–compression test results. The two methods of analysis of dynamic tests gave similar results. Calibrations from the tension–compression and dynamic tests also show an overall good agreement. However, the dynamic tests back analysis gave a slightly higher value of the norm of the complex modulus and a lower value of the phase angle compared to the tension–compression test data. This result may be explained by the nonlinearity of AM (strain amplitude is at least 100 times smaller for dynamic tests) and/or by ageing of the materials during the period between the tension–compression and the dynamic tests.

Four-Parameter Viscoelastic Model for the Plates of Uniformly Varying Cross-Section

2018 ◽  
Vol 382 ◽  
pp. 196-200
Author(s):  
Gülçin Tekin ◽  
Fethi Kadıoğlu
Keyword(s):  
Cross Section ◽  
Mixed Finite Element ◽  
Viscoelastic Model ◽  
Material Behavior ◽  
Solid Model ◽  
Static Response ◽  
Kirchhoff Plates ◽  
Inverse Transform ◽  
Linear Viscoelastic Material ◽  
Linear Viscoelastic

This study aims to investigate the quasi-static response of linear viscoelastic Kirchhoff plates of uniformly varying cross-section subjected to time-dependent loads. Four-parameter solid model is used for defining the linear viscoelastic material behavior. Through an efficient systematic procedure based on the Gâteaux Differential (GD), a functional has been constructed for the analysis. For the analysis, mixed finite element (MFE) method in transformed Laplace-Carson space is used. For transformation of the solutions obtained in the Laplace-Carson domain to the real time domain, Dubner & Abate (D&A) numerical inverse transform technique is employed.

scholarly journals On the ABAQUS FEA Model of Finite Viscoelasticity

2009 ◽  
Vol 82 (2) ◽  
pp. 184-193 ◽  
Author(s):  
J. Ciambella ◽  
M. Destrade ◽  
R. W. Ogden
Keyword(s):  
Viscoelastic Model ◽  
Constitutive Law ◽  
Fea Model ◽  
Dissipation Rates ◽  
Finite Viscoelasticity ◽  
Linear Viscoelastic ◽  
Abaqus Model

Abstract Predictions of the QLV (Quasi-Linear Viscoelastic) constitutive law are compared with those of the ABAQUS viscoelastic model for two simple motions in order to highlight, in particular, their very different dissipation rates and certain shortcomings of the ABAQUS model.

Polysaccharide Structures in the Outer Mucilage of Arabidopsis Seeds Visualized by AFM

2020 ◽  
Author(s):  
MAK Williams ◽  
V Cornuault ◽  
AH Irani ◽  
VV Symonds ◽  
J Malmström ◽  
...  
Keyword(s):  
Average Length ◽  
American Chemical Society ◽  
Md Simulations ◽  
Chemical Society ◽  
Side Chains ◽  
Rhamnogalacturonan I ◽  
Afm Imaging ◽  
Minor Population ◽  
The Stability ◽  
A Minor

© 2020 American Chemical Society. Evidence is presented that the polysaccharide rhamnogalacturonan I (RGI) can be biosynthesized in remarkably organized branched configurations and surprisingly long versions and can self-assemble into a plethora of structures. AFM imaging has been applied to study the outer mucilage obtained from wild-type (WT) and mutant (bxl1-3 and cesa5-1) Arabidopsis thaliana seeds. For WT mucilage, ordered, multichain structures of the polysaccharide RGI were observed, with a helical twist visible in favorable circumstances. Molecular dynamics (MD) simulations demonstrated the stability of several possible multichain complexes and the possibility of twisted fibril formation. For bxl1-3 seeds, the imaged polymers clearly showed the presence of side chains. These were surprisingly regular and well organized with an average length of ∼100 nm and a spacing of ∼50 nm. The heights of the side chains imaged were suggestive of single polysaccharide chains, while the backbone was on average 4 times this height and showed regular height variations along its length consistent with models of multichain fibrils examined in MD. Finally, in mucilage extracts from cesa5-1 seeds, a minor population of chains in excess of 30 μm long was observed.

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