How to put temperature for Viscoelastic analysis in Abaqus?

[ENGLIAO]

I have difficulty in finding where to put temperature for viscoelastic analysis in Abaqus 6.6.3. To do viscoelastic analysis, I prepared shear modulus data and constants for WLF equation. But I could not find where to put the temperature to which my material is subjected for each running. I hope someone here can give me a hint. Thanks ahead of time.
---GENLIAO

[ashu28]

Hello Genliao,

I know a couple of ways to do it, though have never tried it myself.

1. For standard constants of WLF, use *TRS option
2. Write user subroutine UTRS to define your own shift functions.


I would like to know which one works out for you, as I would be also needing it very soon.

--Ashu

[ENGLIAO]

Hi Ashu,

I may not express myself clearly.
I used WLF constants (reference temperature, C1 and C2) and shear modulus to build Prony model ( which is to be done by Abaqus internally). ALso I defined instantaneous elastic modulus and poisson's ratio. THen I could run Abqus w/o error. However, to run abaqus each time, you should specify a loading time and temperature to check the effects of them on response of the model. I know the loading time can be obtained from specified loading waveform. But I do not know where to specify the temperature for each running.
BTW, there is one location temperature can be specified when you define elastic parameters. But when I varied this parameter, it did not affect my results. This cannot be true because we know temperature plays an important role.
I do not what is your studying object. for me, it is asphalt concrete.

[Grant]

ENGLIAO,

You have to specify the temperature as an initial condition for the analysis step. The temperatures are specified at nodes. If your structure is all at the same temperature, put all nodes in a node set called ALLNODES or something, and then use the syntax

*initial conditions, type=temperature
ALLNODES, 72.0 (or whatever temperature you want)

Keep in mind that if you defined any temperature-dependent properties, there is a reference temperature associated with them. It has to be consistent with the temperature scale you use to apply the temperature initial condition.

[ENGLIAO]

Thanks, Grant.

I found there is one location I can define teperature (I am using Abaqus/CAE). In the "Step", I can use "predifined fields" to give a tepmerature to different layers. However, the results are surprising because strain at higher temperature is smaller than that at lower temperature (all other parameter are identical). I am trying to figue it out.
---ENGLIAO