Tek-Tips is the largest IT community on the Internet today!

Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!

Register Log in
  • Congratulations TugboatEng on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Search results for query: *

  1. jrw501

    Bridge Modeling

    We use LUSAS primarily and I find it quite capable and handy. I think it's somewhere between your RISA/SAP2000s and something like ABAQUS. I also have some experience with MDX and while it has some positive aspects (I think it's relatively easy to learn to use), but I've had negative...
  2. jrw501

    Help selecting element- hyperelastic, adaptive meshing

    Not sure if this helps, but I've used hyperelastic material models (Neo-Hookean and Mooney-Rivlin) with C3D8, C3D8H, C3D8I, elements before without issue.
  3. jrw501

    Stability/Energy Question from ABAQUS output

    For a structure that I believe to have passed its stability point (based on load-deflection behavior that has passed a point with zero tangential stiffness/went through a maximum) can anyone confirm that at that I should be able to verify the stability point has been reached using energy output...
  4. jrw501

    Mesh Convergence Issue

    That's a good point, I'll try fixing the elevation aspect ratio. I actually think I may be starting to observe convergence similar to what is seen in the displacement-mesh density graph shown here: http://machinedesign.com/article/converging-on-an-accurate-solution-0413. I'm going to give a...
  5. jrw501

    Mesh Convergence Issue

    The shear load is being applied as a prescribed displacement as you guessed. The real bearing is circular (annular), but only half of the bearing has been modeled (which is probably most easily seen in the 3rd image when looking at the top) to reduce the number of elements. The plane of...
  6. jrw501

    Mesh Convergence Issue

    I would guess part of the reason it takes so long to run is that the problem becomes numerically difficult to solve as the horizontal stiffness starts approaching 0. I'm not using any really high performance computers either. I was tending away from 2nd order elements because some of the...
  7. jrw501

    Mesh Convergence Issue

    I meant to add that it is these locations of critical displacements that are varying for each mesh size. So under axial load X, I get critical displacements a, b, and c for the various mesh sizes where a~1.1c and c~1.1b.
  8. jrw501

    Mesh Convergence Issue

    I suppose relative to some meshes these are somewhat coarse, but the "fine" mesh takes about 24-36 hours to run locally and the operation needs to be performed multiple times for each mesh size. As far as what's being done, the bearing is being shear under constant axial load -- at some point...
  9. jrw501

    Mesh Convergence Issue

    http://files.engineering.com/getfile.aspx?folder=2acc2d83-290f-41cf-ace2-3895617f41f9&file=b2.JPG http://files.engineering.com/getfile.aspx?folder=af3092f0-8a03-4179-aff3-3849fcda3f46&file=b3.JPGhttp://files.engineering.com/getfile.aspx?folder=af3092f0-8a03-4179-aff3-3849fcda3f46&file=b3.JPG
  10. jrw501

    Mesh Convergence Issue

    b1: medium mesh elevation b2: medium mesh results b3: fine mesh perspective The main difference between the meshes is the number of elements radially and the bias of each element outward to maintain an aspect ratio of approximately...
  11. jrw501

    Mesh Convergence Issue

    I'm using C3D8H and C3D8I elements (3D solid elements) -- the bearings are composite elements of steel and rubber, the steel is using the incompatible modes, the rubber is using the hybrid formulation since it's nearly incompressible. The criteria being used to determine instability is when the...
  12. jrw501

    Mesh Convergence Issue

    In case this is helpful, I probably should've added that the results from the medium mesh are about 10% smaller than the fine mesh, and the results of the coarse are about 10-15% larger than the fine mesh. I guess another question I had was should I just invest time in creating a 4th mesh...
  13. jrw501

    Mesh Convergence Issue

    Hello, I'm new to FEA/FEM and was wondering if anyone has encountered the following problem with mesh density sensitivity before: For some background, I'm using ABAQUS to model seismic isolation bearings to determine stability/critical behavior at various displacement levels. Anyway, I've...

Part and Inventory Search

Back
Top