thermal expansion (constant temperature)

thermal expansion (constant temperature)

Anonymous
Not applicable
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Message 1 of 6

thermal expansion (constant temperature)

Anonymous
Not applicable

Hi,

 

is there a quicker way to set up a thermal load, directly in linear static mode, without having to do a thermal simulation?

 

I have a shell model, where a constant temperature load should be applied to all the geometry.

 

Thanks

Marco

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Message 2 of 6

david_cordova
Autodesk
Autodesk
Accepted solution

Hi.

 

Before answering your questions, I'd like to add some comments for the larger audience that might read this.  You should only perform a thermal simulation (heat transfer solution) if you are interested in finding thermal results (temperatures, heat flux, etc) due to thermal loading.  It is not possible to get these thermal quantities by performing a structural analysis (linear, nonlinear, dynamic) nor is it possible to define thermal loads in a structural analysis.  If you have a temperature distribution, whether it be a uniform temp or one found from performing a heat transfer solution, you can use that as a load in a structural analysis.  This is normally referred to as a thermal expansion or a thermal stress analysis.  Thermal expansion/stress is not the same as a heat transfer solution.

 

To answer you questions though, as I explained above, thermal loads like convection, radiation, heat flux are not applicable in a static analysis and cannot be used.  Temperature can be a structural load and you should have no problem applying that in your linear static model.  To do this simply create a new load, under the Type, choose "Body Temperature" - this will create a uniform temperature throughout the entire model.  Note that there's also a "Temperature" type that allows you to define a temp on specific entities rather than the entire body.

 

If your intent is to model an initial and final temperature to perform a thermal expansion analysis, then this is what needs to be done:

  • Define a load, set the TYpe to "Body Temperature" at set the value to the final temperature.
  • Create an additional load, set the Type to "Initial Condition", make sure Sub Type is "Temperature" and set the value to your initial temperature

 

Hope that helped.

Message 3 of 6

Anonymous
Not applicable

Hi David,

 

that helped indeed. First time I tried it, I simply wasnt allowed to pick faces for the temperature load, thats why I didnt try it again and thought I had to use the thermal sim in advance. Now it worked.

 

I've also found that the reference temperature of the material will be used as the "initial, stress free" temperature of the model, if I have no initial temperature load. If I specify the latter, it will overwrite the material temperature. Can you verify that?

 

A last question: I've found for that analysis I'm performing and also for another one I did before, that the thermally induced stresses are very high due to the constraint's stiffnesses. Is there a quick way to use springs (instead of boundary conditions) on geometric entities like faces or edges, like in Simulation Mechanical? The spring connectors look a bit archaic here (or I'm not able to use them correctly).

 

Thanks

Marco

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Message 4 of 6

david_cordova
Autodesk
Autodesk

You are correct that the reference temperature in the material definition will be used if no initial temperature is specified.

 

The springs in In-CAD are intended to connect two points together, unfortunately there isn't a way to connect springs across an entire surface.  If the fixed constraint is unrealistic then you will need to free some degrees of freedom.  I would consider constraining the most important component/s, and creating springs, perhaps at the corners of the surface to add stiffness for the unconstrained DOF.

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Message 5 of 6

jsteffle
Enthusiast
Enthusiast

Does anyone know if there is a tutorial (or series of tutorials) that might exist that would take me through these steps?

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Message 6 of 6

Anonymous
Not applicable
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