A Model for Hyper-Elastic Material Behavior Under Thermal Aging With an Application to Natural Rubber

2018 ◽  
Author(s):  
Ahmed G. Korba ◽  
Abhishek Kumar ◽  
Mark E. Barkey
Keyword(s):  
Natural Rubber ◽  
Aging Time ◽  
Elastic Material ◽  
Thermal Aging ◽  
Least Square ◽  
Material Behavior ◽  
Model Parameters ◽  
Stress Strain ◽  
Strain Behavior ◽  
Hyper Elastic

Numerous hyper-elastic theoretical material models have been proposed over the past 60 years to capture the stress-strain behavior of large deformation incompressible isotropic materials. Among them, however, only few models have considered the thermal aging effect on model parameters. Having a simple, closed-form equation that includes the effect of aging temperature and time in describing the stress-strain behavior could facilitate fatigue analysis and life time prediction of rubber-like materials. In this vein, this paper defines a new and simple Weight Function Based (WFB) model that describes hyper-elastic materials’ behavior as a function of aging time and temperature variations. More than 130 natural rubber specimens were thermally aged in an oven and tested under uni-axial loading to observe their stress-strain behavior at various temperatures and aging times. The temperature ranged from 76.7 °C to 115.5 °C, and the aging time from zero to 600 hours. The proposed WFB model is based on the Yeoh model and basic continuum mechanics assumptions, and it was applied to the tested natural rubber materials. Moreover, it was verified against Treloar’s historic tensile test data for uni-axial tension of vulcanized natural rubber material, and also compared to the Ogden and the Yeoh models. A non-linear least square optimization tool in Matlab was used to determine all hyper-elastic material model parameters and all other fitting purposes. The proposed model has better accuracy in fitting Treloar’s data compared to the Ogden and the Yeoh models using the same fitting tool under the same initial numerical conditions.

New Model for Hyper-Elastic Materials Behavior With an Application on Natural Rubber

2017 ◽  
Author(s):  
Ahmed G. Korba ◽  
Mark E. Barkey
Keyword(s):  
Natural Rubber ◽  
Test Data ◽  
Pure Shear ◽  
Testing Machine ◽  
Shear Loading ◽  
Least Square ◽  
Elastic Materials ◽  
Stress Strain ◽  
Strain Behavior ◽  
Hyper Elastic

This paper is concerned with defining a new Weight Function Based model (WFB), which describes the hyper-elastic materials stress-strain behavior. Numerous hyper-elastic theoretical material models have been proposed over the past 60 years capturing the stress-strain behavior of large deformation incompressible isotropic materials. The newly proposed method has been verified against the historic Treloar’s test data for uni-axial, bi-axial and pure shear loadings of Treloar’s vulcanized rubber material, showing a promising level of confidence compared to the Ogden and the Yeoh methods. A non-linear least square optimization Matlab tool was used to determine the WFB, Yeoh and Ogden models material parameters. A comparison between the results of the three models was performed showing that the newly proposed model is more accurate for uni-axial tension as it has an error value which is less than the Ogden and Yeoh models by 1.0 to 39%. Also, the parameters calculation by more than 95%, for the bi-axial and pure shear loading cases compared to the Ogden model. Natural rubber test specimens have been tensioned using a tensile testing machine and the WFB model was applied to fit the test data results showing a very good curve fitting with an average error of 0.44%.WFB model has reduced processing time for the model.

A hyper-elastic thermal aging constitutive model for rubber-like materials

2019 ◽  
Vol 52 (8) ◽  
pp. 677-700
Author(s):  
Ahmed G Korba ◽  
Abhishek Kumar ◽  
Mark Barkey
Keyword(s):  
Natural Rubber ◽  
Thermal Aging ◽  
Biaxial Loading ◽  
Strain Curve ◽  
Aging Effect ◽  
Elastic Materials ◽  
Stress Strain Curve ◽  
Stress Strain ◽  
Hyper Elastic ◽  
Uniaxial And Biaxial Loading

Different phenomenological, empirical, and micromechanical constitutive models have been proposed to describe the behavior of incompressible isotropic hyper-elastic materials. Among these models, very few have accounted for the thermal aging effect on the model constants and parameters. This article introduces a new empirical constitutive hyper-elastic model for thermally aged hyper-elastic materials. The model named “the weight function based (WFB) model” considers the effect of aging temperature and time on its parameters. The WFB model formulation can facilitate fatigue analysis and lifetime prediction of rubber-like materials under aging conditions. The WFB model in this article defines all rubber-like material properties, such as fracture stretch, strength, and stiffness, by predicting the full stress–strain curve at any aging time and temperature. The WFB model was tested on natural rubber for uniaxial and biaxial loading conditions. More than 100 specimens were aged and tested uniaxially under various temperatures and aging times to extract the stress–strain behavior. The temperatures used in the test ranged from 76.7°C to 115.5°C, and the aging time ranged from 0 to 600 hours (hrs). A classical bulge test experiment was generated to extract the biaxial natural rubber material behavior. An ABAQUS finite element analysis model was created to simulate and verify the generated biaxial stress–strain curve. The proposed model represents the aging effect on the tested natural rubber under uniaxial and biaxial loading conditions with an acceptable error margin of less than 10% compared to experimental data.

scholarly journals Preparation and stress-strain behavior of in-situ epoxidized natural rubber/SiO2 hybrid through a sol-gel method

2018 ◽  
Vol 12 (2) ◽  
pp. 180-185 ◽  
Author(s):  
S. M. Li ◽  
T. W. Xu ◽  
Z. X. Jia ◽  
B. C. Zhong ◽  
Y. F. Luo ◽  
...  
Keyword(s):  
Natural Rubber ◽  
Sol Gel ◽  
Epoxidized Natural Rubber ◽  
Stress Strain ◽  
Gel Method ◽  
Sol Gel Method ◽  
Strain Behavior

Influence of Crosslink Characteristics Induced by Aromatic-Based Antioxidants on the Swelling and Stress-Strain Behavior of Natural Rubber Vulcanizates

2003 ◽  
Vol 76 (2) ◽  
pp. 334-347 ◽  
Author(s):  
Tarek M. Madkour ◽  
Rasha A. Azzam
Keyword(s):  
Natural Rubber ◽  
Crosslinking Agent ◽  
Oxidative Degradation ◽  
Thermal Oxidative Degradation ◽  
Stress Strain ◽  
Strain Behavior ◽  
Strain Induced Crystallization ◽  
Elastomeric Chains ◽  
Natural Rubber Vulcanizates ◽  
Induced Crystallization

Abstract Stress-strain measurements were performed on dry and swollen natural rubber vulcanizates prepared using both sulfur as the crosslinking agent and aromatic-based bound antioxidants acting as a second crosslinking agent. The aromatic-based antioxidants were synthesized and analyzed spectroscopically in order to relate the final behavior of the vulcanizates to the nature of the crosslink characteristics. The anomalous upturn in the modulus values of these networks in response to the imposed stress was shown to persist in the dry as well as the swollen state. Since the swollen elastomeric chains cannot undergo a strain-induced crystallization, the abnormal upturns in the modulus values in an absence of a filler were explained on the basis of the limited extensibility of the short chains of networks prepared using two different crosslinking agents in line with earlier modeling predictions. Remarkably, the swelling experiments revealed the increase in the crosslink density of the networks in the early stages of the thermal oxidative degradation procedure indicating a post-cure of the chemically bound antioxidants to the elastomeric chains, which incidentally corresponds to a maximum in the modulus values of the networks. The rheological and other mechanical properties such as the hardness were shown not to have been affected as a result of the incorporation of the chemically bound antioxidants.

Hyperelastic Muscle Simulation

2007 ◽  
Vol 345-346 ◽  
pp. 1241-1244 ◽  
Author(s):  
Mohd. Zahid Ansari ◽  
Sang Kyo Lee ◽  
Chong Du Cho
Keyword(s):  
Skeletal Muscle ◽  
Silicone Rubber ◽  
Soft Tissues ◽  
Material Model ◽  
Incompressible Material ◽  
Material Behavior ◽  
Rubber Tube ◽  
Stress Strain ◽  
Element Analysis ◽  
Strain Behavior

Biological soft tissues like muscles and cartilages are anisotropic, inhomogeneous, and nearly incompressible. The incompressible material behavior may lead to some difficulties in numerical simulation, such as volumetric locking and solution divergence. Mixed u-P formulations can be used to overcome incompressible material problems. The hyperelastic materials can be used to describe the biological skeletal muscle behavior. In this study, experiments are conducted to obtain the stress-strain behavior of a solid silicone rubber tube. It is used to emulate the skeletal muscle tensile behavior. The stress-strain behavior of silicone is compared with that of muscles. A commercial finite element analysis package ABAQUS is used to simulate the stress-strain behavior of silicone rubber. Results show that mixed u-P formulations with hyperelastic material model can be used to successfully simulate the muscle material behavior. Such an analysis can be used to simulate and analyze other soft tissues that show similar behavior.

The Stress-Strain Behavior of Natural Rubber

1957 ◽  
Vol 30 (4) ◽  
pp. 1027-1044 ◽  
Author(s):  
F. Horst Müller
Keyword(s):  
Natural Rubber ◽  
Theoretical Data ◽  
Deformation Condition ◽  
Stress Strain ◽  
Theoretical Evaluation ◽  
Strain Behavior ◽  
Heat Effects ◽  
Deformational Behavior ◽  
Deformation Processes ◽  
The Relationship

Abstract This treatment of the stress-strain behavior of natural rubber is based upon experimental and theoretical data on the cold stretching of high polymers gathered from work being in progress for some time at Marburg. These investigations indicate that deformation processes of matter should not be treated exclusively as purely mechanical phenomena though this is still being done. Especially in the case of natural rubber there exist very thorough analyses of these heat effects caused by deformation. Their theoretical evaluation furnished the basis for the thermodynamic-statistical theory of rubber elasticity. This created the picture of a molecular mechanism which with new additions permitted the description of a host of details including those for stress-strain behavior. However the relationship between the shape of the stress-strain diagrams and any particular deformation condition can only be explained if the actions of the deformational heat effects upon the course of the deformation are considered. In the following an attempt will be made to discuss the actions of the heat effects, in other words to examine the deformation processes as mechanical-thermal ones. Although there are, at present, no experimental results on hand, the expected consequences for the deformational behavior of rubber will be surveyed. Experimental work is in progress.

Probabilistic Structural Analysis for Advanced Space Propulsion Systems

1990 ◽  
Vol 112 (2) ◽  
pp. 251-260 ◽  
Author(s):  
T. A. Cruse ◽  
J. F. Unruh ◽  
Y.-T. Wu ◽  
S. V. Harren
Keyword(s):  
Structural Analysis ◽  
Material Behavior ◽  
Nonlinear Material ◽  
Significant Advance ◽  
Space Propulsion ◽  
Stress Strain ◽  
Ongoing Research ◽  
Strain Behavior ◽  
Nonlinear Stress ◽  
Random Material Properties

This paper reports on recent extensions to ongoing research into probabilistic structural analysis modeling of advanced space propulsion system hardware. The advances concern probabilistic dynamic loading, and probabilistic nonlinear material behavior. In both cases, the reported work represents a significant advance in the state-of-the-art for these topics. Random, or probabilistic loading is normally concerned with the loading described in power spectral density (PSD) terms. The current work describes a method for incorporating random PSD’s along with random material properties, damping, and structural geometry. The probabilistic material response is concerned with the prediction of nonlinear stress-strain behavior for physical processes that can be linked to the original microstructure of the material. Such variables as grain size and orientation, grain boundary strength, etc., are treated as random, initial variables in generating stochastic stress-strain curves. The methodology is demonstrated for a creep simulation.

Behavior of Different Fractions of Purified Hevea Rubber during Vulcanization

1949 ◽  
Vol 22 (4) ◽  
pp. 994-999
Author(s):  
G. T. Verghese
Keyword(s):  
Molecular Weight ◽  
Natural Rubber ◽  
The Other ◽  
Stress Strain ◽  
Strain Behavior ◽  
Other Hand ◽  
The Difference

Abstract Considerable data on the vulcanization characteristics of molecular fractions of ordinary (unpurified) natural rubber are available. There is, on the other hand, little information of any systematic work on the vulcanization of purified rubber and of its fractions. Pummerer and Pahl vulcanized the sol and gel fractions obtained from purified Hevea rubber, and also the purified whole rubber. But apart from a statement that whole rubber vulcanized much faster than the two fractions obtained from it, no details have been published. Vulcanization of purified whole rubber and of its sol and gel fractions was studied also by Smith and Holt. They concluded that the difference which they observed in the stress-strain behavior of the fractions and whole rubber was due to differences in the rubber which persisted through vulcanization. The present paper deals with a study of the vulcanization characteristics of different fractions of purified rubber prepared by a method described in a previous paper. Also, for comparative purposes a similar study was made of the corresponding fractions of unpurified rubber. As the difference in molecular weight of some of the fractions obtained by the above method was rather small, a grouping of the fractions was made as follows :

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