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LFSS

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  1. It worked perfectly! Thank you very much!
  2. I've double-checked them, and they are all assigned correctly. Am I missing something here? I'm sure that they are not being used,.
  3. Strange. In my optimization, only the elements using the PBEAML ID 1 card are being optimized. Since I'd like to use them all, how can I correct my model?
  4. Hello. As the title suggests, I'm getting this error for all my PBEAML cards except the one with ID 1. What does this error mean?
  5. Hello, i'm trying to figure out what's the difference between these two output options. CBAR/CBEAM gives me normal stresses while Element Stress gives me Axial Stress. The difference between results is an order of magnitude apart, so I really need to know what each one is actually outputting. I've search the documentation but I couldn't find a suitable answer.
  6. Thanks a lot man!
  7. That's interesting. So the difference between my first model (with the SPC rigid linked to 2 nodes) to my second one (SPC rigid linked to three nodes) is that in the second one I get a overstiffened structure relative to the first one, did I get it right? As for the buckling, thanks for the advice! Just out of curiosity, how do you display the tubes like that? I only get the line contour, but this one you showed here has a better visualization!
  8. I understand. I'll try it later today. I've attached the model file to the original post.
  9. They are composed of two rigids, one for yellow and one for brown. I've made sure the middle one is the independent node for both of them, as well as where the SPC and the force is applied. What's the difference for an RBE3? is it better for my case?
  10. Hello everyone. I'm working on a project which consists of a rod-trussed structure .I'm having some difficulties working with rigids. I have followed the Altair's student frame linear static analysis. Since I need my SPC to be in a rigid, the configuration is this one: I am using two rigids: one for the SPC and another one for applying a force (brown line). Whenever I use the configuration above, OptiStruct says there's dependency between rigids (because the two rigids are applied to the same node). So, in order to fix that, I have tried this configuration: Which yields this result: But if I try to run a different configuration (for example, linking the SPC rigid to 3 nodes, except the one where the force rigid connects), I get this result: Which basically zeroes my displacements and stresses in the model. I have no ideia which one is giving me more realistic results and I'd could use some help trying to figure it out! Thanks File_Forum.hm
  11. Turns out I was doing basic math wrong. Sorry for the inconvenience, guys!
  12. My understanding of unrealistic comes from past experience from working with those carbon fibre tubes/rods. I don't think that a 1m tall trussed structure could have a mass of 480kg as OptiStruct says. Nonetheless, I might be commiting an error somewhere and not seeing it, so that's why I asked. Yes, I'm using rod elements to validate my structure. Does it change something? Even with rods it shouldn't be that heavy...
  13. Hello everyone, I'm working on a project which consists of a carbon fiber truss structure (.hm file annexed below) and, even though I've got the right material properties inputed, the result mass is nearing 480kg for a 1m tall trussed structure. I've cheched my units and it's consistent all over the board (MMTS system). I have no idea what can be causing that, can anyone help? File_Forum.hm
  14. Hello, I am trying to perform a size optimization much like the Altair's tutorial on that matter. But there's something I need that's not covered within the tutorial. I need to add a set of tubes with varying diameters into the solver, so that the solver can only choose these kind of tubes. How may I do that? Just for reference, this is the database I need to put into the solver: https://goodwinds.com/carbon-fiberglass/carbon/pultruded-tubes.html
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