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Found 6 results

  1. Hello, I'm currently trying to optimize the laminate of a cfk part with the free sizing optimization. At the end of the run it states "OPTIMIZATION HAS CONVERGED" "FEASIBLE DESIGN (ALL CONSTRAINTS SATISFIED)" but the programm is just reducing the mass while the displacement constantly gets bigger and is far bigger than the max displacement constraint I set for the optimization. The total displacement constraint is set to -2mm. Min ply thickness is set to 2mm and max 50mm.
  2. Hi, I'm working on a spherical Vacuum vessel (external pressure > internal pressure) using an isogrid structure. I made a shell model with sphere skin and additional ribs to have more stiffness and avoid buckling. Now, I'd like to perform a free-size optimization, to see if there are particular shapes and thickness distributions that minimize the mass of the system. I tried different optimization sets (min mass + constraints on buck, min compl + constr on buckling and mass), but every optimization ends with "Unfeasible design", with very large violations of buckling constraint. Could you give some hints? Thank you so much Enrico
  3. Hello everyone, I'm currently running an composite optimization on a part and today I noticed that the mass I get on the .out file and on the model I import after the size optimization is different. On this optimization, I try to minimize the compliance of the part while constraining the mass between 3200g and 3600g. Here is what I get on the .out file: Here is what I get on the imported model: While on the output file I get a total mass of 3600 as requested, when I import the model, the total mass is now 5322. I've searched around, followed tutorials and nothing helped. I tried opening the *.inc file as suggested on tutorial OS-3400 but the result is the same (the same as if I just import the .fem file resulting from the free size optimization). I've looked on this forum and I found something about the CMF file instead but after the free size optimization, I only get the *.HM.ent.cmf and not the *.HM.comp.cmf as mentioned here: I also tried running the optimization with MATINIT set to 1 on opticontrol but once again, the result is the same... Can someone please help? Thank you very much!
  4. Hello, I have defined dconstraint for my free size and size optimization of my composite layup. there I am trying to reach a maximum displacement of 0.7mm. With this, I am not sure what bound to set, in order to get a sufficient displacement solution. Can you hell me out with this problem? THank you in advance for your help. Kind regards Dean
  5. Hello, I have a problem regarding free sizing optimization with Laminates. After free sizing optimization when optistruct creates 4 plies of each fibre orientation there remain exactly the first ply of each fibre orientation which has the shape of the whole design space. In my case the 4 plies are grouped together as the first plies of my model. I attached a picture of my problem. I tried difference settings with TMANUF, min, max Laminat thickness. But the problem is always the same. All plies based on the same elements. To introduce Loads I used RBE3 and RBE2 elements and connect them to the elements. Do you have any suggestions how to fix my problem? Thank you in advance Do you have any suggestions?
  6. Hallo everybody. I want to run a free size optimization with Optistruct. My model is an Formula Student Monocoque. Everything is ok until I set the optimization. I have got 9 loadcases. One of them is pure torsion. Now, that´s what I have done so far. - I set the design variable "free size" - I set a response static displacement and took two nodes (dof 3) with an dconstraint, lower an upper bound and all loadsteps - I set a response mass with an objective min I set the cards: - PARAM, in_rel=-2 - GLOBAL_OUTPUT_REQUEST: CSTRAIN and CSTRESS - OUTPUT: FSTOSZ I set opticontrol: - DESMAX= 80 - OBJTOL= 0.005 - DELTOP= 0.5 The Check is ok, but when I start an optimization there is an fatal error after about 20 minutes. INFEASIBLE DESIGN Then I tried to make an new response. The displacement response only with the loadstep with the pure torsion and another response with composite failure and the other eight loadsteps. But the free size card don´t support that response. The check and optimization .out files are attached. FInaly my question. Is there any way, how I can fix it. Or another way I can run an optimization? Thanks for your help check.txt optimization.txt
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