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sbalazs

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  1. I think that a possible solution could be if I could turn on and off the contacts on different loadsteps. Is this possible in Optistruct? If yes, how? Thanks in advance for your answers! Regards, Szilard
  2. Hi , I have to create an analysis for a large assembly where: 1 in the first step I have to pretension some screws 2 then I have to apply a press fit 3 then have to pretension some other screws 4 apply some loads My question would be, if I create a PCONT with CLEARENCE option for the press fit, how can I be sure that this will make his effect just in the second step by me and only there and not on every other steps too, since for this option there is no need for an explicit loadstep. Thanks and regards, Szilard
  3. Hi Rahul, thank's a lot for your help! Reagrds, Szilard Balazs
  4. Hi Rahoul, did you find out something about this Optistruct bug? Is there really no solution for this problem? How can I perform this analysis in an another way? Regards, Szilard Balazs
  5. Hi, I used the same fem file which I used for the Optistruct 14 run (see atached files from my first post), I only used the Optistruct 2017 solver (since I want to do the same analysis ) .... Is it wrong doing so ? Regards, Szilard
  6. Hi Rahoul, here are the results when I run the same input files under Optistruct 2017. My problem is that the same pretension lodcase (enforced displacements in a local csys) produces different results whether there is a follower loadcase or not..... Regards, Szilard
  7. Hi, thanks for your answer, I tried to solve with Optistruct 2017, unfortunately occours the same problem....We don't use Optistruct 2018 at the moment. Regards, Szilard
  8. Hi, I tried to model the pretension for a NLGEOM analysis with enforced displacements in a local csys. If the pretension is not followed by an another loadcase, the results are OK, if there is a follower loadcase the results are not the same as before and wrong. Attached you can find a test model (with pretension with and without an additional loadstep). Nodes id. 1 and 2 are the ones with enforced displacements in the local csys id 4. Please take a look at the displacements for the pretension in both cases. Is this problem known? Is there a workaround for this problem? Thank you. Best regards, Szilard Balazs example_NLGEOM_pretens_load.zip
  9. Hi Prakash, thanks a lot for your answer. You made that comment in this same topic, into I added my question too, a few posts higher. I hope my model works properly in the way I modelled it, with the springs that have 3 DOF's nelinear and 3 DOF's linear. I'm waiting your answer regarding the slope. Best regards, Szilard Balazs
  10. Hi Prakash, thanks for your answer. regarding my 2. question : if optistruct takes a slope, which slope does it take - each pair of values define a slope, which one is taken, how can I understand the 'at zero deflection' therm? What do you think about my first question, can it be modelled as I did? Because above at 15.June.2015 you wrote : ' A spring will be either linear or Non linear in all DoFs. So, if X, Y are non-linear then physically other DoFs should be non linear. ' Best regards, Szilard Balazs
  11. Hi Prakash Pagadala, 1. I have a same problem, 3 DOFs linear and 3 DOFs neliniar. How should I model my modell in this case? Is this correct: PBUSH 3 K0.0 0.0 0.0 28650.0 28650.0 28650.0 PBUSHT 3 KN 29 30 31 TABLED1 29 + -10.12-38799.0 -9.77-34584.0 -9.44-30866.0 -9.13-27587.0 + -8.84-24695.0 -8.57-22144.0 -7.98-17030.0 -7.46-13186.0 + -6.98-10296.0 -6.53 -8124.0 -6.11 -6490.0 -5.7 -5263.0 + -5.32 -4340.0 -4.95 -3646.0 -4.58 -3124.0 -4.22 -2732.0 + -3.87 -2438.0 0.0 0.0 3.87 2438.0 4.22 2732.0 + 4.58 3124.0 4.95 3646.0 5.32 4340.0 5.7 5263.0 + 6.11 6490.0 6.53 8124.0 6.98 10296.0 7.46 13186.0 + 7.98 17030.0 8.57 22144.0 8.84 24695.0 9.13 27587.0 + 9.44 30866.0 9.77 34584.0 10.12 38799.0ENDT $$ TABLED1 30 + -20.15-96415.0 -19.7-93975.0 -19.26-91574.0 -18.81-89212.0 + -18.38-86887.0 -17.94-84601.0 -16.97-79487.0 -16.02-74558.0 + -15.1-69808.0 -14.19-65230.0 -13.31-60817.0 -12.43-56564.0 + -11.59-52465.0 -10.75-48515.0 -9.95-44707.0 -9.16-41037.0 + -8.38-37500.0 0.0 0.0 8.38 37500.0 9.16 41037.0 + 9.95 44707.0 10.75 48515.0 11.59 52465.0 12.43 56564.0 + 13.31 60817.0 14.19 65230.0 15.1 69808.0 16.02 74558.0 + 16.97 79487.0 17.94 84601.0 18.38 86887.0 18.81 89212.0 + 19.26 91574.0 19.7 93975.0 20.15 96415.0ENDT $$ TABLED1 31 + -4.52-13173.0 -4.28-11825.0 -4.06-10626.0 -3.87 -9560.0 + -3.68 -8612.0 -3.52 -7769.0 -3.28 -6637.0 -3.08 -5689.0 + -2.89 -4894.0 -2.72 -4228.0 -2.57 -3671.0 -2.43 -3203.0 + -2.3 -2812.0 -2.18 -2484.0 -2.06 -2209.0 -1.96 -1979.0 + -1.86 -1786.0 0.0 -450.0 1.86 886.0 1.96 1079.0 + 2.06 1309.0 2.18 1584.0 2.3 1912.0 2.43 2303.0 + 2.57 2771.0 2.72 3328.0 2.89 3994.0 3.08 4789.0 + 3.28 5737.0 3.52 6869.0 3.68 7712.0 3.87 8660.0 + 4.06 9726.0 4.28 10925.0 4.52 12273.0ENDT 2. What does this text mean?: *** WARNING # 3065 PBUSH/PBUSHT 3: Ki (i=1) is zero and the corresponding KN-TIDi is given. In linear analysis, Ki is overwritten by the slope of KN-TIDi at zero deflection. I get this text when I'm running a linear analysis with PBUSHT. In my first example means this that Optistruct takes for : Tx = 0 N/mm, Ty = 0 N/mm and Tz = -450 N/mm ? Thanks in advance and best regards, Szilard Balazs
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