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    • Rahul Ponginan

      Please click here for a short but important announcement   03/26/17

      Dear Users Our Commercial and Academic users around the world can use these same forums here as before i.e. the Altair Support Forum , Commercial users from India with solver queries can go to the Solver Forum for India Commercial Users , Academic Users from India and AOC India Participants are requested to go to the Forum for India Academic Users and AOC India Participants , We will be tending to all queries in all the forums promptly as before, thank you for your understanding. 


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  1. [GNA] Post-Buckling of arch plate in Optistruct

    I think I solved it for my own, of course the N,DT combination just divides the given load profile in increments
  2. [GNA] Post-Buckling of arch plate in Optistruct

    Another question: While using "Nonlinear transient" I want to load 0.25*25 for 0,1 sec and after that linear progression to 1*25 MPa at 1 sec. Therefore I created a TABLED1 with 3 entries: 0.0 -- 0.25; 0.1 --0.25; 1 -- 1. This table I am using for a TLOAD1 table entry and my force with 25 as well. But now my question: will the TSTEP entry in any kind overwrite this? If I have N=100 and DT=0.01 will the solver still use the table entry?
  3. [GNA] Post-Buckling of arch plate in Optistruct

    This works (see attached)! PlateTest_run.fem Video.avi
  4. [GNA] Post-Buckling of arch plate in Optistruct

    Hi, are there any updates concerning our benchmark?
  5. [GNA] Post-Buckling of arch plate in Optistruct

    "TSTEPNL 7 500 0.0 1 UPW" *** ERROR # 1000 *** in the input data: Incorrect data in field # 4. This error I get, no Idea how to go on
  6. [GNA] Post-Buckling of arch plate in Optistruct

    Ok, I have no idea how to set it up, could you try it or shell I work into this topic
  7. [GNA] Post-Buckling of arch plate in Optistruct

    Hello, Know, using NLSTAT, I dont get the expected results. I attached the concerning files. I am not able to plot Load vs Displacement (I cant choose Nodes for either Load or Displacement using h3d, for .res I cant choose Loads as Y reference). Therefore I cant realy say, whether my results are right (as in the Benchmark). The solver doesnt converge at a specific increment, therefore I think he cant go through the whole deflection cuve). Could you look at the results and try to get a Load vs Displacement graph? PlateTest.out PlateTest.h3d PlateTest.res PlateTest.fem
  8. [GNA] Post-Buckling of arch plate in Optistruct

    Thank you for the tip. I would like to plot the load increments over the Displacement, but maybe with oload it works
  9. [GNA] Post-Buckling of arch plate in Optistruct

    Another thing, I was using the geometric nonlinear analysis load step, which indeed uses RADIOSS. I will try the Nonlinear quasi static loadstep with large Displacement and report back. The post process problem exists anyways, so it would be kind to get help with that.
  10. [GNA] Post-Buckling of arch plate in Optistruct

    I think I got an update, see files attached. I think it could be the solution, but the post processing isnt working as I imagine: 1) also I solved 1700+ time steps, I only get a view (they are actually ordered by deflection size) to e.g. animate the model behaviour (The time steps solved go ++, than --, than ++ again, as supposed, but the time steps in the drope down menu from HyperView are only from 0 to ++, so around 180). 2) again, how to plot time steps (the actual one solved, not the sorted, censored ones) against displacement? (For validation and comparison) PlateTest.h3d PlateTest.out PlateTest.stat PlateTest.res PlateTest_rad_s1_0001.out PlateTest.fem
  11. [GNA] Post-Buckling of arch plate in Optistruct

    I only quoted the post from the RADIOSS forum, because it was also a plate, so you can imagine the problem.
  12. [GNA] Post-Buckling of arch plate in Optistruct

    As I pointed out, it was just a similar problem. I am used to Optistruct and want to use it, as Optistruct should be capable of solving such a problem (it is a non dynamic behaviour I think, because of that no need for RADIOSS?). There are different sites presenting this, as it is a rather common benchmark: https://enterfea.com/problems-with-nonlinear-analysis-convergence-read-this/ https://www.comsol.com/blogs/buckling-structures-suddenly-collapse/ https://www.youtube.com/watch?v=JS7dgba2qLc Similar load path: https://www.researchgate.net/post/Arc_length_method_for_non_linear_buckling_Nonlin-FEM_in_ANSYS_Is_there_any_way_I_can_continue_the_Simulation_beyond_the_critical_point And here a different Video with snap-back also: https://www.youtube.com/watch?v=o5Nu5GF_zZk ---------------------- I want to go through the whole deflection path with the model I attached in the original post. Normaly, the RIKS ARC LENGHT method should be able to get all points .... as pointed out before, with 1mm shell thickness I only get up to point A....
  13. [GNA] Post-Buckling of arch plate in Optistruct

    Hi, I have several questions concerning the solver deck you send: 1) No buckling occures? I could increase the load, but anyways, I want to get the deflection of the arched plate from the benchmark (post buckling behaviour including area B-D). The model set up for a general GNA is known. 2) Why using NLOAD in this case? Its static anyways. 3) Why including EIGRL in GNA? It isnt used? ---------------------------------------------------------------------------------------- 4) How to plot Load time steps over Displacement (Y-X) in Hypergraph?