New to Abaqus: Thermal Expansion 1

[scifistirfry]

Hi everyone, I finished school recently and have started my first job as a mechanical engineer. One of the things I am tasked with doing right now is to perform Abaqus thermal stress simulations on a thermoelectric generator. I have no previous experience with Abaqus so i'm looking for some help/guidelines. I'm starting small, with small examples and going to work my way up to eventually modelling the whole TEG. for now though, all I want to do is a simple thermal expansion.

I have entered my material properties and designed a rectangular part (representative of my element). I want to see how much it expands when the temperature increases by 100 degrees celsius with no mechanical boundary conditions. every way i try to do it gives me errors when i submit the job due to too many iterations. my prodecure clearly has something wrong.

all i want to do is make sure my abaqus calculation concurs with my analytical one. it's length is 0.25m, so the piece should expand 0.25xCTEx100 in that direction, but i have not been able to achieve this result in abaqus.

thanks in advance!

 

[burningDiesel]

easiest would be if you upload an input file.
What I guess is wrong is that you don't put any boundary condition. you should at least remove rigid body motion.
Are you seeing warnings in the msg file? Zero pivit, numerical singularities, ... ?

Other than that, check your units for consistency, be sure to use an element type with thermal DOF, etc.

 

[scifistirfry]

I have tried putting in boundary conditions and predefined fields. I have been primarily trying to use a coupled temp-displacement step.

The warnings i get are "There is zero HEAT FLUX" and I have also gotten Zero Pivot error on DOF 11 when I've tried doing it different ways. After several repetitions of the "THere is zero HEAT FLUX" warning I get a "Too many iterations error".

What is process that you would go through to do this simple type of simulation.

 

[burningDiesel]

if you got your BC's right you should get a whole bunch of zero force and zero heat flux warnings, as there will be zero force and zero heatflux anywhere.
how to do it:
see the simple example in attachment, i just put some random values for all parameters.
do file->import->model
its not the cleanest but you should manage to find your error

 

[scifistirfry]

thanks for your help, I was able to successfully model basic thermal expansion! I am now trying to add a surface heat flux to a plate to see how it behaves. I get no warnings, but I get an error saying "too many attempts made for this increment". i know this is a very generic error. also, should I repost with a different title?

 

[burningDiesel]

probably you need to reduce the initial (or maximum) time increment, if that is your only error

 

[IceBreakerSours]

Usually, the time increment message is a symptom, not the cause of trouble.

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