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  1. Hello everyone! I am working on a validation problem for a script I have set up previously to load in geometry and loading/material/optimization parameters from Rhino 3D and run through Hypermesh and Optistruct. I am currently trying to run a "high-rise" type of problem - effectively this is a cantilever with point wind loads acting at several points up the height. With this type of loading, we would expect to see a symmetric brace pattern similar to the image I have shown below. What we are actually getting are results that are asymmetric and have material that is not attached to the rest of the structure. Is this because we are using a solid to mesh and solve? Or possibly because of the volume fraction selected? I understand that mathematically, it is possible to have elements that do not seem "connected" to the structure due to the way density is assigned along the continuum. However, I do not understand why we are seeing asymmetric bracing if we have symmetric geometry and loading. Has anyone encountered something like this before? And is there any documentation on the exact methodology employed in OptiStruct to arrive at solutions? I know the SIMP method is used, but I have not had much luck in finding more specific information. Any help or guidance would be greatly appreciated! I have attached the hypermesh model, results files and output, a screenshot of the final results at a density threshold of ~0.4, and an image showing the intended loading and results. vf0.3_min6_wind.hm vf0.3_min6_wind.log vf0.3_min6_wind.out vf0.3_min6_wind_des.h3d
  2. Hi Rahul, Thank you for taking a look - yes there appears to be an issue somewhere in the model, however, I believe the loads and BCs are applied the same as in the example (except that I have substituted the RBEs for tractions). I am going back through again and checking. I uploaded the other files - I thought I had uploaded the .hm yesterday but appear to have selected the wrong one! The files you requested are uploaded now. Thank you!
  3. Hello all, I've been trying to recreate the example problem seen here: https://connect.altair.com/CP/SA/training/self_paced/optimization/content/opt3/pdf/ex1a.pdf But with a couple of modifications: 1. I have written a script to run the model in batch mode, however, the script cannot handle RBEs at this point. I've substituted all RBEs with loads and constraints assigned directly to the surfaces, effectively creating tractions instead of RBEs. 2. The script meshes everything in tetra elements. Everything else should be the same (material definitions, boundary conditions, objective function, etc). I'm thinking that these two modifications shouldn't change the outcome very much, but maybe that's an incorrect assumption? I keep getting an error in Optistruct that the compliance is huge and optimization can't be performed. Any ideas as to why? The model is attached. Any help or guidance is greatly appreciated! vf0.3_min30_wcomp.mvw vf0.3_min30_wcomp_des.h3d vf0.3_min30_wcomp.hm vf0.3_min30_wcomp.fem vf0.3_min30_wcomp.log vf0.3_min30_wcomp_003.out
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