CFD Online Logo CFD Online URL
Home > Forums > General Forums > Structural Mechanics

Thermal Stress - Modelling of an interactive coupled Simulation

Register Blogs Members List Search Today's Posts Mark Forums Read

LinkBack Thread Tools Search this Thread Display Modes
Old   January 10, 2019, 05:14
Default Thermal Stress - Modelling of an interactive coupled Simulation
New Member
Join Date: Feb 2015
Posts: 26
Rep Power: 11
macRC is on a distinguished road
Hello everybody,

Hope you all are fine.

Usually I do thermal simulations for electronics cooling (CHT simulations). This means, we can simulate the overall thermal behavior of the electronics. For that, we have a quite efficient and proper workflow.

An important detail is often the thermal resistance between two parts. E.g. how is the PCB (Printed Circuit Board) mounted on a heatsink. Due to the roughness of the surfaces and the not perfect planarity, there is always a small gap between two parts, usually in the range of 30 m air.
With the assumption of a homogenous thermal resistance of 30 m, we can achieve a very good agreement between simulation and measurements.

The next target now is to model and simulate the 30 m air gap more properly, as we know, the gap is not constant but can vary in a certain range.

For doing so, I think a common approach is a one way coupled thermal stress simulation:
- - Performing a thermal simulation as usual in order the get the thermal behavior of the parts
- - Map the result and perform a structural simulation considering the different coefficients of thermal expansion (CTE) and observe the deformation of the parts

Now, the gap is not constantly 30 m any more, but can vary in a range of let’s say 0 – 60 m due to the deformation (its now a function of the place).
Since the gap can have a big impact on the thermal results, I would like to perform another thermal simulation, with the new “air gap function” and not with the homogeneous 30 m. Thus I would expect slightly different thermal results. This new thermal result will end in a different deformation and air gap function respectively. If this works, I could do a slope thermal, stress, thermal, stress and so on until there is convergence.

Unfortunately the implementation of all that is not so easy. I did some investigations with different approaches, but the success is negligible so far

Do you have some ideas or hints of performing such "2 way coupled thermal stress simulations"?
I use Star-CCM+ and so far there are only two mechanical interfaces – bonded and Small Sliding Firctionless.

Attached you can find a sketch of the domain.
This example shows a simplified LED module mounted on a heatsink.
Thank you very much in advance.
Kind regards
Attached Images
File Type: jpg electronics1.jpg (41.5 KB, 14 views)
File Type: jpg electronicsdetail.jpg (71.5 KB, 11 views)

Last edited by macRC; January 10, 2019 at 07:12.
macRC is offline   Reply With Quote


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
Simulation of thermal time of flight (CFD + Fluent) YuguiYo ANSYS 0 April 28, 2016 09:08
MCM modelling and thermal simulation phurba Main CFD Forum 0 September 9, 2015 11:29
Thermal stress and strain Javaid26 Structural Mechanics 7 August 6, 2015 09:52
[stressAnalysis] Steady-state thermal stress analysis by using solidDisplacementFoam Sargam05 OpenFOAM CC Toolkits for Fluid-Structure Interaction 16 September 13, 2012 08:04
error message cuteapathy CFX 14 March 20, 2012 06:45

All times are GMT -4. The time now is 19:30.