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OptiStruct

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  1. Hello everyone I have a model with two load steps: heat transfer and linear static. It would be very helpfull to set a temperature constraint for the topology optimization (dconstraint). It is possible to create a temperature response. To assign a constraint to the response, a load step have to be selected - I though the heat transfer load step should be selected, as it contains all the thermal calculation, but this is not possible. The message 'Selected subcase (Heat transfer) is not compatible with the type of response.' comes. How can I set a thermal constraint (maximal temperature) for a topology optimization? Thank you in advance for your help!
  2. Actually I have only increased DESMAX. It seems like it scales everything up - that by increasing DESMAX it takes more time, as it takes more iterations to optimize.
  3. Hello everyone As an optimization reached the limit of iterations, I have set a DESMAX. Is it possible, by setting a higher DESMAX, more iterations are needed for the same progress. Because since a set DESMAX to a higher number, the progress time has slown down - instead of taking 24h for a progress of 50% it now takes almost double the time and a higher amount of iteration to reach 50% total progress. Thank you in advance for your help.
  4. Okay I can assign MID and H1. But there is still a problem. The temperatures are not including any convection. Can I still use MAT4 and specify there the thermal conductivity (K) and leave the heat transfer coefficient (H) empty?
  5. Thank you Rahul! Does this interface come from the group 'CONVECTION'? Because the default there is FTYPE 0, with which I can assign MID, but no H1. If I change FTYPE to 3 I can assign a H1, but no MID. Do you know why I can't assign both?
  6. Hello everyone As there is convection, I use MAT4, which also contains the heat transfer coefficient H. Now I am woundering, how can you specify two different heat transfer coefficient on certain surfaces of the model? The heat transfer coefficient is actuallly not a material property, so I am woundering if this is the right way to go. How can two different heat transfer coefficient be assigned? Thank you in advance for your help!
  7. The structural load case does not take effects on the thermal load case. The volume should be optimized with a stress constraint, so from the structural load case.
  8. Yes I have seen this tutorial. This tutorial is mainly a thermal analysis and optimization. In my case, there is a statically defined component with pressure difference (=mechanic) and a temperature difference (=thermal). So there are basically two load steps, a heat transfert(steady state) load step with SPC=spc_thermal and a linear static load step with SPC=spc_mechanical and LOAD=pressure. Is there something important to take into consideration with this sort of thermo and mechanical optimization? Thank you for your help!
  9. Great that worked very well! Thank you very much!
  10. Hello everyone I would like to do a thermo-mechanical optimization. The thermo-mechanical analysis is already done successfully. Now I was looking for a documentation or tutorial about this sort of topology optimization, but I could not find anything. Does anybody of you have a link or documentation to share, about thermo-mechanical topology optimizations? I thank you very much in advance!
  11. Hello everyone Can someone give me an advice on how to indicate that a certain surface have a temperature of 20°C and another surface of 80°C? And also indicate the pressure of those surfaces? In order to get thermal and mechanical results of it? I thank you in advance for your help!
  12. Hello everyone I would like to know, what is the difference between creating a constraint, set its Card Image to TEMPD, set T1 with the temperature and to create 'temperatures' and set the value to the temperature? I thank you in advance for your help!
  13. Great thank you very much! Is there also a way to cut it with the coloured element quality check?
  14. Hello everyone I have a quite complexe geometry to mesh. For this I have applied 'Check Elements Quality Index', where it shows the quality of the elements. Now I would like to know, if there is a possibility to cut the model, to be able to see the inner contours and how the elements looks there. Then I could have a better overview of the situation and know what to change for the mesh. I thank you in advance for your help!
  15. Hello I would like to know if there is a possibilty in Hypermesh to convert a surface model to a volume model? Thank you in advance for your help!
  16. Hello Is it possible to highlight in colour only the lattice structure? I get only one component, which contains the lattice elements as well as the full material. So they both have the same colour. I thank you in advance for your help!
  17. Hello Is there a difference if you set MINDIM or MINMEMB? You can go either to Analysis>Optimization>Topology>Parameter and then change minmemboff to mindim with a value, which will assign it to the Design Variable Property. Or you can go to Analysis>Optimization>Opticontrol and set MINDIM with a value, which creates a new optimization control named 'optistruct_opticontrol'. Thank you in advance for your help!
  18. How does the MINDIM work? I have changed the elment mesh size to 7.5 mm and set MINDIM to 0.5 mm. But I still get lattice structures with smaller diameters (Ømin=0.038 mm).
  19. Hello Thank you! Well the minimum diameter is also related to the element size. I guess by setting a mesh with enough big elements, will create bigger lattice structures.
  20. Hello Normally a lattice optimization does create lattice structures of different elements. Does a way exist to set a minium diameter of the lattice structure? I know the function 'MINRAD', which cleans in the second optimization phase and eliminates all elements above the set value. If I use MINRAD, almost all lattice structures are eliminated, as they are quite small (between 0.0027 and 0.335 mm). The ideal lattice structure would have diameters above 0.5 or 1 mm. How can this be set? I thank you in advance for your help!
  21. Perfect! Thank you very much!
  22. Here are two extracts from the <filename>_lattice.fem: CBEAM 12983 6184 7674 37285 1.25373 2.25 1.75 PBEAML 2 1 ROD + .1790678 0.0 1.0.1790678 What column stands for the diameter? Thank you for your help!!
  23. Hello I have made a lattice optimization. Now I would like to measure the diameter of the lattice beams. Do you know how to measure them? I thank you in advance for your help!
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