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Error# 2148: Invalid design problem.

Hello,

I am doing a topology optimization with objective to minimize the thermal compliance.

I get the following error.

A fatal error has occurred during computations:

*** ERROR # 2148 ***
Invalid design problem.
All the sensitivities of response 2 (objective) are zero.

I have attached the .out file, I would like to know what the possible reasons for this error could be.

Would there be any example files to share if there is a topology optimization involving CFD and thermal inputs with Optistruct.

Regards,

test.out

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English

OptiStruct

v2021.2

Accepted answers

RobHoglund

Hello Sam,

The Thermal Compliance is extremely high for the heat transfer subcase.

Subcase Thermal Compliance
1 3.494810E+20

Can you check and review your model unit system for the heat transfer analysis and the fixed temperatures and thermal loads?

You can run a baseline analysis without the optimization on the model to check and see if the temperature results make sense first (use run option -optskip).

OptiStruct also has Darcy Flow topology optimization capability for flow channel optimization considering heat transfer. See here:

https://help.altair.com/hwsolvers/os/topics/solvers/os/darcy_flow_analysis_intro_r.htm?zoom_highlight=darcy+flow

Thanks,

Rob H.

All comments

RobHoglund

Hello Sam,

The Thermal Compliance is extremely high for the heat transfer subcase.

Subcase Thermal Compliance
1 3.494810E+20

Can you check and review your model unit system for the heat transfer analysis and the fixed temperatures and thermal loads?

You can run a baseline analysis without the optimization on the model to check and see if the temperature results make sense first (use run option -optskip).

OptiStruct also has Darcy Flow topology optimization capability for flow channel optimization considering heat transfer. See here:

https://help.altair.com/hwsolvers/os/topics/solvers/os/darcy_flow_analysis_intro_r.htm?zoom_highlight=darcy+flow

Thanks,

Rob H.

Sam George

Hello Robert,

Thanks for the response.
I have made relevant changes and now the temperature is correct.

I have another issue now regarding the topology constrains.

Here the seven faces had to be in non-design space for convection to work.

Post the optimization run, this how it looks.
Design Space

Covection interface

The elements which look like shell needed to be defined in convection interfaces, is supposed to be in design space.

Note: The simulation is done on a heatsink with Heat Flux on the PCB.

Parts involved: PCB, Heatsink Baseplate, Fins( solid block)

Design Space: Fin( solid block)

Non-design space: PCB, Heatsink baseplate

Expected outcome is a branched fin structure.

2D result:

Regards,

Sam George