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Hi,
I am tryin to minimize the structural cost using a custom function for a topology optimization, however I am running into an error.
*** ERROR # 557 *** DRESP2 16 is not referenced above the first SUBCASE. This type of response must be specified above the first SUBCASE. This error occurs in DESSUB 14.
How can I resolve this error?
Please find the attached .fem and .out files.
Thanks,
Tyo
Your DREPS2 #16 is this. You've set DRESP2 #16 as subcase dependent. The DRESP2 #16 does not need subcase information anymore.
However, when you use DRESP2 #16 for a optimization constraint, you did add subcase infomation to it. This is too much.
As the result, the DRESP2 #16 is reffered from a subcase,
Once you clear the loadstep in the constraint entity editor,
The wrong DESSUB is removed, and the constraint using DRESP2 #16 is merged to DESGLB.
Indeed, as the error message said, now the response DRESP2 #16 is specified 5 lines above SUBCASE #1,
You have same errors for DRESP2s in your model. I hope my explanation is enough for you fix all of them.
Thank you for your response. I was able to resolve the error and run the optimization. However, the results did not provide a define "truss-like" pattern." The results of the contour plot of the element density is all under the dark blue region.
It may be due to the optimization strategy using the structural cost objective function.
I switched the approach and optimized for stiffness (compliance) with a constraint on mass together with the displacement constraint, and received a more defined pattern.
Is there a way to optimize for the structural cost and still receive results with a defined pattern?
Below I have attached the .fem and .out files for the two different optimization approaches:
Hello,
Your question is consulting matter. I just help very basic like how to fix the error, how to use, but dont't help how to obtain a expected result in the community. I think "Try and Error" is user's matter in the community.
Thus, If you need deeper help, please contact to account manager and technical account manager for your organization.
However, I can add very general matters, not special for your case. Generally, when OptiStruct topology optimization says the whole part does not need elemental density, the part is not needed for your purpose.
For example, if the part is not exist, no stress occurs. When the purpose is reducing the stress, the answer should be removing all of the part.
You've applied the purpose for the part to be there. Thus, OptiStruct topology optimization returns the result which says that the part should be there.
