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Hello everyone, For the purposes of a shape optimization I need to conduct for my Master's thesis, I wanted to optimize a response that is partially based on a sum of the Von Mises stress values of several elements (100+) in a certain element set of my model mesh. My initial idea was to do it using a DRESP2 card, set the function as sum, and give as a response input my static stress > Von Mises response; I then realised that the sum function actually sums the response values of multiple separate responses, and not the individual values of multi-output Optistruct responses such as stress or displacement. Is there any feasible workaround for this, other than maybe writing a DRESP3 external function that would take all Von Mises stress values of elements within a certain element set, and churn out the sum of them all or any other scalar value I would need? Defining a stress response for every single element in my set would not be a feasible solution because of the very high number of elements I have in the set of interest. Thank you and appreciate any insight from you on the matter
Hy, I would like to calculate a special safety value from stress responses, and using it in topology optimization. The test of this calculation is started with a simple problem. DRESP1 case 1: - constaint: DRESP1 (von mises stress response, one selected element) - objective: DRESP1 volume DRESP2 case 1: - only response: DRESP1 (von mises stress response, one selected element) - constaint: DRESP2, (equation response) is calculated the following equation a(x)=x and using the DRESP1 von mises response - objective: DRESP1 volume In this case the changes on design variables are the same, and the results are the same. Than i changed the response element quantity to 2 and the DRESP1 and DRESP2 case results are different I have tried to change constraint screening, nothing has changed I have tried to look on sensitivity values, but no stress values included in *.asens files or *_topol.h3d files I have tried to compare it with displacement response/constraint and they are good, so the DRESP1 and DRESP2 with 2 response nodes has the same results. Is this problem connected to Stress-NORM aggregation ? How can i turn ON Stress-NORM aggregation in DRESP2 case? How can i examine the stress response sensitivities? Did i miss someting in the setup? I have attached the 2 different *.hm and *.fem files Thanks, CSR dresp1_simp.fem dresp1_simp.hm dresp2_simp.fem dresp2_simp.hm
Hello Everyone, I am trying to do thermo structural analysis in optistruct. later I have to continue optimisation on structural analysis. Basically thermal expansions are only load for my optimization problem. I faced following difficulties and trying to resolve them, 1. thermo structural analysis in optistruct- ---- I have referred all tutorial and discussion available a I did find any direct method to read temperature from my thermal analysis and apply it as load in structural analysis. I have pipe carrying hot fluid and I have convection heat loss so direct TEMP use in static is not possible for me and off course I have referred Coupled Linear Heat Transfer/Structure Analysis , however problem is I need to use structural subcase id as reference to my optimization so I cant use CASE_UNSUPPORTED_CARDS control card. 2. How to request temperature output in static analysis---- some how if I am able to run structural run with TEMP in static analysis, I will have to compare my temperature contour. So how can I request thermal output in static analysis results. (already have tried loadstep--> edit-->OUTPUT-->THERMAL. didnt work) 3. How can I use DRESP2 in optimization, already have found one discussion on same but corresponding tut link is expired. Basically I want to use relative displacement in my optimization as constraint. Thank you