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malcolmdinovitzer

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About malcolmdinovitzer

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  1. Hello, I am working on a model in hypermesh where the loads are applied at a single dependent node and transferred to multiple independent nodes. I would like the RBE3 weighting factor to change between groups of nodes. Can I assign different weighting factors to different independent nodes in a single RBE3 element? If not, how can I apply my loads? I have tried using multiple RBE3 elements (one for each weighting factor) except I get the following error (Node 189285 is the node where the loads are applied) *** ERROR # 173 *** A dependent d.o.f. defined more than once in rigid element entry. GRID ID = 189285 component = 1 Thanks, Malcolm
  2. Hello Prakash, I have tried Geom>Surfaces>From FE. I am not able to select any of the elements of the non design space. Have you tried this with the file I attached? I would select the elements by the face however I can't do this because I cannot select any of the elements. I have tried starting entirely from scratch and I run into the same issue. Why am I only left with elements and no geometry? Malcolm
  3. Hello, How do I convert FE to Geometry? I also do not see .stl in the export geometry menu Malcolm
  4. Hello Prakash, There are elements in the non design space however there are no solids. File>Export>Geometry [filetype:IGES] does not work for the .fem file. When I use the macro to convert the 1D elements to cylinders and then export to IGES, I end up with only the lattice structure.
  5. Hello, I am trying to perform a simple lattice optimization using optistruct in order to create a tensile specimen with lattice structure. When I run my optimization, a feasible design is found however the resulting .fem file no longer has a solid for the non design space. This becomes apparent when I try to export the results to .iges I've attached the relevant files as reference: ASTM_D638_02a_TypeIII_lattice.fem ASTM_D638_02a_TypeIII.hm Thanks Malcolm
  6. Hello @Prakash Pagadala, RBE2 elements results in the same error. Is it correct for me to have the RBE2/RBE3 elements defined in the nondesign component?
  7. Hello Prakash, I will try that later today but as far as I understand, POROSITY has no effect on the lattice shape or size. POROSITY only effects the penalization of the elements with intermediate densities. Setting POROSITY to LOW will simply mean that some of the elements with intermediate densities will be converted to solid instead of lattice.
  8. Hello @Prakash Pagadala, Here are some photos from my initial optimization. Since this was only a test run I did not include a minimum radius for the lattice. Hopefully these photos clarify my original question, you can now see the mesh as well as the resultant geometry.
  9. Hello @Prakash Pagadala, I was under the impression that the rbe3 elements constrained the model. If not, I'd like to constrain the model at the two holes shown in the airfoil. Can this be done by adding an SPC at the dependent node of the rbe3 elements? Thanks, Malcolm
  10. Hello, I am attempting to run an optimization using Optistruct but the solver keeps outputting the following error: *** ERROR # 312 *** In static load case 1 the compliance is negative or large 1.7638e+015. Optimization/buckling analysis cannot be performed. due to possible rigid body mode. INFEASIBLE DESIGN (AT LEAST ONE CONSTRAINT VIOLATED). From what I understand, this error could be from a model that is not fully constrained or from poorly defined materials properties. My model is constrained with 2 RBE3 elements so I believe my constraints are not the issue and I don't understand what could be wrong with my material inputs. I have attached my model for reference. Any help would be appreciated Thanks ComparisonStudyModel.hm
  11. Hello, I am working on a project where lattice optimization will be performed on a part that will eventually be printed using additive manufacturing. From what I understand, after performing a topology optimization using optistruct, the elements with a density between UB and LB will be converted into lattice structure. Based on some trial analysis, it appears that each element is converted into it's own lattice "unit cell". For a fine mesh this presents a problem as the lattice structure will be too small to print. Is there any way to continue using a fine mesh for accuracy but to have a larger lattice created? I can also use a larger mesh, but with the complex geometry I suspect the optimization will be significantly less accurate.
  12. Hello @George P Johnson, Thank you for the help. I have deleted the solid and can now also see the line that is causing the issue. Could you please also explain how I can remove this line and repair the geometry? I have been unsuccessful so far Where is the duplicate surface? I am trying to use Geometry > Defeature > Duplicates but no duplicate surfaces are found.
  13. Hello, I am working on setting up a model for a simple topology optimization and I am consistently running into the same error when trying to form a mesh. I have meshed the entire design space and part of the non-design space but the final solid always results in an error of "1 edges failed nodal setup. Meshing failed". I have not been able to find any information about this error online so far. I have attached a photo of the error message and a photo of my model prior to meshing. The attached model includes the failed mesh as a "tmp" component. Is there an error in my geometry? How would I be able to mesh this final solid? Thanks ComparisonStudyModel.hm
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