Constitutive relations, 2-D vs. 3-D. The starting point for modeling cellular membranes is the constitutive relations in 2-D space. It is important to set up the corresponding equations directly in two dimensions rather than to consider them as an asymptotic limit of three-dimensional relationships, like it is done in the shell theory. The main reason for the direct 2-D relations is that 3-D continuum approaches are not applicable to membranes whose thickness in on the order of magnitude of the dimension of a single molecule.
I am trying to model a sheet of Poly Vinyl Butryl (PVB), which is a viscoelastic material in ANSYS. I have all the regular properties like elastic, shear and bulk modulus, poisson ratio, denstiy and damping factor. I also have a stress- strain curve of PVB. With all this data, is it possible for me to find the various constants in the viscoelastic models using ANSYS?
Dielectric elastomer, as an important category of electroactive polymers, is known to have viscoelastic properties that strongly affect its dynamic performance and limit its application. Very few models accounting for the effects of both electrostatics and viscoelasticity exist in the literature, and even fewer are capable of making reliable predictions under general loads and constraints. Based on the principals of nonequilibrium thermodynamics, this paper develops a field theory that fully couples the large inelastic deformations and electric fields in deformable dielectrics.
I have the shear relaxation modulus given as: G(t)=Go*EXP(-t/tau). In ABAQUS, the normalized shear modulus for one term in Prony series is given as: g(t)=Go(1-g1(1-EXP(-t/tau)). The parameters that must be entered in ABAQUS are g1 and tau. For Maxwell (in our case) G(t=infinity)=0.
Consequently, g1=1-G(t=infinity)/Go=1. ABAQUS requires that g1 must be less than 1. Has anyone encountered this problem?
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?
Hi, has anyone tried the bushing example from abaqus' problems manual? The full name of the section is: transient loading of a viscoelastic bushing. The job is aborted due to some unknown set. Thanks.
I would like to use Abaqus to model the viscoelastic material behaviour of a polymer.
I have material data from a simple uniaxial creep experiment (nominal strain vs time). I tried to use the viscoelastic material model in Abaqus. I am a bit confused as to how I need to enter my data (what format).
The manual says I have to specify the normalized bulk and normalized shear compliance .
I wish to inform the imechanica community about my recent book, Polymer Engineering Science and Viscoelasticity, Springer, 2008. THe book starts at the beginning and contains both the physics of polymers and the mathematics of viscoelasticity. It is also unique in the history of mechanics in being the (first ever?) father-daughter book. Those interested in polymer mechanics may find this a useful resource! It may be found in your library or further information can be found here
An internship position is available in the area of Finite Element Analysis of Elastomers in the Simulation and Modeling Group at Schlumberger, Sugar Land, TX.
I am trying to implement quasi static fracture in a discrete lattice model, with material being viscoelastic. Do i need to use an incremental-iterative method? Please give your suggestions.
I am trying to use gerenalized maxwell viscoelastic model for polyimide polymer films (Kapton) in MSC Marc (or ABAQUS). I have never used the prony series representation of the maxwell model (hereditary integral approach). Has anyone ever used MSC Marc to incorporate the prony series relaxation to the material? or ABAQUS? Here is my game plan for doing this:
Before we start this issue of J-club, I would like to recommend Prof. Langer's lecture for his MRS Von Hippel Award in the 2005 MRS Fall Meeting (Langer, 2006). His lecture not only delineated the history of the new exciting field of drug delivery and controlled release, but also told us many interesting stories happened in his career development. With Prof. Langer's pioneer work, many new materials are developed for designing new drug delivery and controlled drug release systems.
Does any one know how to implement other viscoelastic material models, like Burgers' model, in ABAQUS? To my knowledge only Prony series can be used to model visoelastic materials in ABAQUS/standard.
, the modulus ratio in the first term in the Prony series expansion of the shear relaxation modulus."
, the modulus ratio in the first term in the Prony series expansion of the bulk relaxation modulus."
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and normalized shear compliance )
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