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hyperelasticity

computational nonlinear elasticity references

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I will be developing constitutive material models into commercial FE codes for nonlinear elasticity and searching for good books to get started for computational aspects. There are many good books for computational plasticity but I did not find any for nonlinear elasticity. Suggestion for good books or references is welcome.

Contact problem

Hello 

 

Iam trying to model an orthodontic apparatus movement. Can anyone help me how to choose the type of interaction between the three parts. In attached the assembly. THE steps are : the ring will be opened then it will descend finally the ring will return to its initial position can anyone tell me how to choose interaction properties. Thanksa  lot 

 

Abaqus query on UMAT: NaN issues

Hello, I have a written a UMAT for a hyperfoam type material in Abaqus. To validate it I am comparing my UMAT results with that from a *HYPERFOAM material definition. I am facing a particular problem: 

Compression buckling of polymeric beam/column

Hello,

I have a problem with a stacked colum of elastomeric membranes (natural rubber or silicone).

I am looking for a compression buckling criterion that applies for hyperelastic materials in presence of large deformations (up to 400%).

I've read about Haringx formula, that should apply for these materials, but I suspect that it is valid for small strains only.

My question is:

- is there a suitable buckling criterion for this case?

Jiang Chen's picture

How to get the update the local material coordinate in large deformation for hyperelasitc rubber-like materials?


Hello, 


I want to ask things about the updation of local material coordinate in large deformation. 


Does there exist two ways for this?


1. Polar decomposition of Gradient Deformation Tensor F to get the rotation tensor.


2. Update each basis vector of local material coordinate system using modified Gradient Deformation Tensor F_bar = F*J^(-1/3).

Required - Verification test for Incompressible hyperelastic models

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Hi,

I am working with a finite element code implemented in C++ in my research group. Recentl I implemneted an incompressible finite strain element.

 Currently I am making use of verification tests to check whether my element runs accurately for various hyperelastic strain-energy models. I have succesfully completed a verification test using the Mooney-rivlin strain-energy density function. However, I have been unable to find verification/benchmark tests which I may use to test other strain-energy density functions.

Compatibility error: Type Volumetric

Hi all

i was performing 2D asymmetric analysis of rim mounting on tire.

i was using hybrid elements and the following error is appearing. 

 MAX. PENETRATION ERROR 265.670E-03   AT NODE 50327 OF CONTACT PAIR
   (CARCASS-1_CONTACT,RIM-1_CONTACT)
   MAX. CONTACT FORCE ERROR 7.46319E+03 AT NODE 10327 OF CONTACT PAIR
   (CARCASS-1_CONTACT,RIM-1_CONTACT)
          PENETRATION ERROR TOO LARGE COMPARED TO DISPLACEMENT INCREMENT.

Anisotropic plasticity and hyperelasticity in Abaqus

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I am trying to model a polymer that has been processed in such a way that it has oriented (orthotropic) material properties and undergoes very high strains (>100%) before break.

3rd International Conference on Material Modelling incorporating the 13th European Mechanics of Materials Conference

Dear Colleagues,
During the last decades material modelling has become a field of central
scientific importance. Although there exist many workshops, meetings,
colloquia, etc. on specific materials, and particular applications, here a
single conference dedicated to material modelling with all its various
facets is intended. To this end, the aim of the ICMM conference is to bring
together researchers from the various fields of material modelling and
materials characterization. The intention here is to cover essentially all

Constitutive models for rubber

Hi.

I found a very useful explanation about hyperelasticity here: http://en.wikipedia.org/wiki/Hyperelastic_material#cite_note-Ogden-1

 In the proof3, there is a good explanation (I can't found anything better than this one) of how we can express the Cauchy stresses in terms of the principal streches.

I am interested to incompressible material, so this is the equation:

Jacobian matrix of Mooney-Rivlin model

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Hi,

does anyone know where I can find the analytical expressions for the components

of the Jacobian matrix of the Mooney-Rivlin model.

I know the compact form of the matrix, with the tensor products, deviators etc,

but I'm looking for the explicit expressions of each component of the matrix.

 

many thanks!

 

 

 

anisotropic hyperelastic ansys subroutine

Recently i work on finite element model of a human vertebral body, and focus on intervertebral disc.

Based on its structure which consist of collagen fibers i have to use anisotropic hyperelastic model with reinforced fiber, and i derived the coefficients of strain energy function.

but i have some troubles to modeling this material in ansys v.10 or v.12, because i have to use user material subroutine and i have not enough information about how to define material with macro in ansys

wvmars's picture

Hyperelastic material characterization: why they call it the pure shear specimen

Many people puzzle over the nomenclature of the pure shear test. They rightly point out that 1) the Pure Shear test piece is loaded in tension by extending the specimen in the axial direction, and 2) a shearing deformation, by definition, involves the lateral motion of parallel planes. They wonder where is the "shear"? and what does it mean to say that the shear is "pure"?  Here, we review the origins of the terminology. 

Izabela's picture

hyperelastic or elastic skin model in Abaqus

Dears,  I am quite new in the area of Abaqus models and biomechanics. My background is related with textiles. However I am a post doc in Belgium at the moment and my new task is to model a fingertip skin section under the influence of contact with different objects.

St. Venant-Kirchhoff constitutive law in Abaqus

I would like to conduct simulations in Abaqus using a St.
Venant-Kirchhoff constitutive law, but when I try to define a material
in Abaqus CAE I do not see it as an option.

 

Is this available as a
built-in model?

 Is this just another material model with a parameter set to a specific value? (Hyperelasticity isn't my strongest area.)

gayoub's picture

Postdoctoral position in mechanical and material engineering

My name is Georges Ayoub; I am looking for a postdoctoral research position in mechanical and material engineering in the field of the polymer science, polymer behaviour and fatigue.
I defended my PHD at the beginning of this academic year (2010/2011). I am very motivated to start a Postdoctoral position, at the end of my thesis, in an Anglo-Saxon country.

gayoub's picture

Postdoctoral position in mechanical and material engineering

My name is Georges Ayoub; I am looking for a postdoctoral research position in mechanical and material engineering in the field of the polymer science, polymer behaviour and fatigue.
I am presently preparing my last year of PHD at Lille1 university (north France) and ill defence my thesis in September 2010. I am very motivated to start a Postdoctoral position, at the end of my thesis, in a Anglo-Saxon country.

Ahmad Rafsanjani's picture

Writing User Subroutines with ABAQUS

Dear All,

 I think that many students are looking for some tutorials about writing a UMAT in ABAQUS.

You can find a comprehensive tutorial for elastic problems.

This file contains: 

• Motivation

Mario Juha's picture

Consistent linearized tangent moduli for hyperelastic materials... is it always a positive definite matrix?

In order to obtain numerical solution of problemsthat involves a hyperelastic material model, we use what is known as incremental/iterative solution techniques of Newthon's type. The basic idea is to contruct a discrete system of nonlinear equation, KU=F, and solving it using a Newton's method or a modified version of it. As we know, its lead to a systematic linearization of the internal force vector and by the chain rule to the linearization of the material model.

Determination of material Mechanical Properties in ANSYS using Force-Displacement graph obtianed experimentally

Hi all.

I am a doctor course student in Biomechanics in Nagoya University - Japan.

I read a bunch of papers in which the determining the conffecients of hyperelasticty of the skin soft tissue was done by using FE Simulation of an expermiment that can be performed on the skin then TWEAKING (IN FACT ANSYS SUPPOSE TO HAVE AN ITERATIVE MODEULE TO DO THIS) the conffecients so THAT the force-displacement results from the simulation are close enough to the ones obtained from experiment.

NOW:

I have the Experiment results

QLV (Quasi Linear Viscoelasticity) vs Linear Viscoelasticity

Can anyone explain what is main difference between Linear Viscoelasticity vs qlv (Quasi linear Viscoelasticity) proposed by Fung.  As far as I understand stress relaxation function and elastic response functions separated and given in convolution form which provides "strain rate independent" results in qlv application.  

Is linear viscoelastic description is strain dependent?

Quasi Linear Viscoelasticity vs. Linear Viscoelasticity

Can anyone explain what is main difference between Linear Viscoelasticity vs qlv (Quasi linear Viscoelasticity) proposed by Fung.  As far as I understand stress relaxation function and elastic response functions separated and given in convolution form which provides "strain rate independent" results in qlv application.  

Is linear viscoelastic description is strain dependent?

Internship available in FEA of elastomers

Internship Announcement  

Title : FEA of Elastomers

Category: Internship in Industry

Employer: Schlumberger Technology Corporation

Location: Sugar Land, TX, USA

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