thermal analysis

[albert1981]

Dear all,

I would like to make a thermal analysis by inputting a tempreature as a load and see the following distribution of stresses. When I create a new step I choose the option to make a coupled temperature-displacement analysis which give the option to choose some heat flux rather then a simple temperature. Should I change element if so which kind of elements I must use in order to apply both a mechanical load and a thermal load.

Thanks in advance,

Albert

 

[corus]

Temperatures are applied as you would a displacement. If there's no need then don't use a coupled thermal-displacement analysis but run two seperate analyses and save the temperatures to input into your stress analysis as a field in the load module.

corus

 

[albert1981]

Dear Corus,

I input the temperature as a predefined field in the initial step and then let propagates in the other steps but is not influencing the analysis. The stress analysi is the same as the temperature is not been inputted. What i am doing wrong?

thanks,
Albert

 

[mizzjoey]

Hi Albert.

I usually run very simple thermal analyses, so I'm not sure if this will solve your problem. But this is what I usually do when investigating effects of thermal expansion:

- insert *Expansion followed by CTE value under the *Material card (you can do this in the gooey (Your Mat Name --> Mechanical --> Expansion --> key in CTE)
- create predefined field named 'temp' and set temp in initial step at 23 (r/t) acting on the desired set(category: other)
- right-click Predefined Fields, choose Manager
- pick the step where the temp changes, click Edit. Then Status: Modified, change magnitude as desired.

Hope this helps,
mizzjoey

 

[corus]

If you're not seeing any effect from the temperatures then you've probably missed out the thermal expansion coefficient. It's easily done. You can also save your input temperatures as an output variable to check if you really are inputting what you think you are, where you want it to go. I've seen anlayses before where the mesh has changed and the temperatures have just been scattered around with the change in node number and position.
If the loads and displacements you've input for the stress analysis aren't being input or recognised then.. I haven't a clue, sorry.

corus

 

[mambo5]

mizzjoey, possible to attached the *INP file of your above mentioned thermal analysis file? many thanks.

 

[mizzjoey]

Hi mambo5.

Haven't logged into this site for a long time! Anyway, here's one example. I created a simple, generic rubber oring part installed in a cavity. The first step is installation and the second is the thermal expansion. Note that I created the predefined field in the initial step. If you don't change the temperature in Step-1, you can set the predefined field to start in Step-1, doesn't matter.

Try running it on your pc. This model is pretty generic (I can't emphasize this enough, just in case my colleagues from the legal dept stumble upon this site - phew!) so you need to check on the CTE of the rubber coz I made up the value

hope this helps,
jo