iMechanica - viscoelasticity - Comments

About nonlinear viscoelastic constitutive relationship

tigerylx — Fri, 08 Oct 2010 12:47:21 -0400

Hi, I am new in the viscoelastic field. I had a question about nonlinear constitutive relationship.

Can this relationship be included into finite element analysis? Which solver(scheme) in commerical software is used to solve the corresponding time dependent problems?

Lixiang Yang

Rayleigh damping....

George Papazafeiropoulos — Mon, 21 Dec 2009 03:16:25 -0500

Hello everyone,

I would like to ask you if there is a way to adjust the Rayleigh damping in ABAQUS Standard to the frequency range under consideration. Is it possible to use multiple steps in a single input file, in which the materials' properties change from step to step?

Tahnk you very much in advance

Could u provide me some tutorials on Creep using Abaqus

guptavk_70 — Thu, 17 Dec 2009 13:51:33 -0500

Dr V. K. Gupta
Associate Professor (Mechanical Engg.)
University College of Engg.
Punjabi University, Patiala (Punjab)
INDIA-147002

Are we considering glass

sn_sohail — Mon, 08 Jun 2009 00:00:08 -0400

Are we considering glass (silicate glasses) as a viscoelastic material? If yes! If yes then how does it deforms? (Maybe obvious but i am a bit confused)

Thanks,

Soheil

Tensorial LAW

chidanand kadakol — Tue, 19 May 2009 13:19:06 -0400

Can i know more about tensorial law for viscoelastic.., as i have developed material modeling and shift factor estimation.., for viscoelastic materials ..,

Regards
Chidu

Rat-independent Fracture Energy

harrywen — Mon, 18 May 2009 01:07:45 -0400

For a viscoelastic mterial, the fracture energy is rate-dependent. Is there an analytical approach to predict fracture energy at one rate (or temperature) from that at another rate?

Thanks!

Harry

Young's modulus

wanbot — Tue, 24 Mar 2009 22:49:39 -0400

Hi all,

I have this confusing thought for a quite long time.

Is there any relation between the time-independent Young's modulus with
the time-dependent Young's modulus (instantaneous and equilibrium
moduli or loss and storage moduli)?

If yes, what is the equation to relate them?

So many terminologies which make this confusion!

Please help.

Wanbot

Let me share my view on

Milli — Fri, 31 Oct 2008 07:51:11 -0400

Let me share my view on your question.

Bulk modulus,K, is often assumed time-indepenent. The reason behind this lies on the assumption that the material in subject is highly incompressible and has a high bulk modulus value.If the material is incompressible, then it implies that the possions ration is nearly 0.5 always and thus can be taken time-indepenent. The main point here is, the material has to be highly incompressible for the assumption to remain valid.

vol. 140 (2003), 1-5

Henry Tan — Tue, 11 Mar 2008 12:36:59 -0400

vol. 140 (2003), 1-5

viscoelasticity

yoshiaki yamada — Sun, 09 Mar 2008 23:52:53 -0400

When I submitted a review article "Time Dependent Materials" to a Monograph Shock and Vibration, Ed. W and B Pilkey, University of Virginia, SAVIAC, 1995, pp.253-284, I found that ABACUS included a well organized capability for viscoelasticity with also a well prepared manual and believe that ABACUS being remained as the most proficient software for the subject by the finite element method.

As an self-introduction, please visit: Journal of Material Processing Technology, Articles in vol.140(1903), 1-5 Y.Yamada, Mechanics of Materials, I saw and participated: a reminiscence.

yoshiaki yamada

viscoelastic

TarekNinouh — Thu, 06 Mar 2008 16:56:56 -0500

Hi I am looking for the development of the law tensoriel viscoelastic
Thank you

toughness in viscoelastic materials

MichelleLOyen — Sun, 13 Jan 2008 07:43:46 -0500

I think this is still quite an open question. Historically it is typical to lump plastic deformation in with toughness such that plasticity is a toughening mechanism. However, since viscoelastic processes are recoverable--just perhaps on a time-scale long relative to the experiment itself--we chose to separately account for viscoelastic dissipation explicitly when looking at fracture of soft tissues. In this case, we subtracted off the viscoelastic part of a hysteresis loop in which energy was dissipated by both viscoelastic and fracture modes. There are relatively few papers on fracture in soft tissues and I think it will take some time before we understand fully whether this is a more useful approach than lumping the two parameters together. But in some unpublished preliminary results we found that the viscous deformation and fracture resistance did not directly correlate, supporting the idea that these are two very different things. For details on our method see the paper linked here .

Re:Particle with inertia in a viscoelastic medium

Biswajit Banerjee — Fri, 04 Jan 2008 13:46:31 -0500

Hi Honglai,

I think the problem of viscoelastic flow around a rigid sphere was simulated by Sugeng and Tanner, 1986,J. Non-Newtonian Fluid Mech., 20, 281-292. There are probably more recent results.

The best text on that sort of thing is, in my opinion, "Dynamic of Polymeric Fluids: Vol.1: Fluid Mechanics", by Bird, Armstrong, and Hassager published by Wiley-Interscience in 1987.

-- Biswajit

Viscoelastic Fracture

vicky.nguyen — Fri, 04 Jan 2008 10:34:40 -0500

Assuming that the failure process is rate-independent (that is the intrinsic fracture energy is constant) you can calculate the increase in the energy release rate from bulk viscous dissipation. For a 3 parameter (standard solid) model, the energy release rate for a fast steady-state growing crack (no inertia) scales with E0/Einfity where E0 and Einfity are the instantaneous and equilibrium Young's moludus.

My paper below includes a bunch of references on this topic.

T.D. Nguyen and S. Govindjee (2006) Numerical study of geometric constrain and cohesive parameters ini steady-state viscoelastic crack growth, Int. J. Fracture, 141, 255-269.

Thao (Vicky) Nguyen
Assistant Professor
Mechanical Engineering Department
Johns Hopkins University
http://me.jhu.edu/~tnguy108

viscoelasticity

vicky.nguyen — Fri, 04 Jan 2008 10:04:44 -0500

Hi Henry,

I just stumbled on your blog regarding viscoelasticity. I work on modeling viscoelasticity, most recently anisotoropic nonlinear viscoelasticity of fibrous tissues. I'd like to address a few of your points:

1) I like Ferry's book Viscoelasticity in Polymers. It's a wonderful mechanics and materials treatment that combines experiments and modeling.

2) Bulk modulus does indeed change with time for a lot of polymers. It's often neglected because for most materials, it changes by a factor of 2 or so while the shear modulus can change by orders or magnitude. Plus it's more difficult to characterize experimentally.

3) If you're dealing with large deformation or with a material where the creep/relaxation rate is dependent on stress/strain you should consider a fully nonlinear treatment. These treatments do not assume a separable time-dependence and strain-dependence of the stress response. These can't be solved analytically, but let me know if you're interested and I can point you to some references.

Thao (Vicky) Nguyen
Assistant Professor
Mechanical Engineering Department
Johns Hopkins University
http://me.jhu.edu/~tnguy108

viscoelasticity

Henry Tan — Fri, 23 Mar 2007 11:30:57 -0400

This blog focuses on viscoelasticity (http://en.wikipedia.org/wiki/Viscoelasticity)