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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. 

Alberto B.

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Alberto B. last won the day on September 29 2016

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  1. Brake squeal analysis

    I've solved the problem, with optistruct 14.0.210 the results are uncorrect, but updating with 14.0.211 the results become correct! Thanks for the support
  2. Brake squeal analysis

    Hypermesh v14.0 full license and solvers patch 14.0.210
  3. Brake squeal analysis

    Hello Prakash, I imported the geometry from a STEP file, then I meshed all on HyperMesh. I did the equivalence for the nodes in common for each body and imposed SPC as the model that i saw on other software. How is it possible that there are free nodes?? Thanks Alberto
  4. Brake squeal analysis

    Hello Prakash, I sent the model. Thanks for the help Alberto
  5. Brake squeal analysis

    Hello Prakash, yes I set a non linear quasi static as first loadstep and then a complex eigenvalue analysis as second loadstep with the nonlinear loadstep in STATSUB (PRELOAD). I used a sample solver deck, that Rahul R sent me, as guidelines (the name of this file is brake_squeal_example.fem), but with the same settings my model gave uncorrect results. In the image attached, you can see the results without FRICESL (fixed slope KT approach from the online help) on the left and those with setting of FRICESL on the right. The results on the left are bad for the too high and too low values (for example frequencies are too low); those on the right are bad because there aren't unstable modes (real parts of eigenvalues are all negative). I tried to change ND values in EIGC and EIGRL ,but I always got uncorrect results. Let me know if there is something i could try for solving this problem. Thank you for the help! Alberto
  6. Brake squeal analysis

    Hello, I'm trying to make a complex eigenvalue analysis with a non linear quasi-static as preload for a brake model. The aim of this work is to determinate unstable modes and to study squeal phenomenon. Using the full version with solvers patch 14.0.210 I succeed to launch the analysis, but the modes extracted are all stable. I tried lots of contact configurations: with the HM contact manager, using gap elements and using superelements with DMIG matrix, but Optistruct always gave the same results. The only way to have unstable modes is to use frictional elastic slip distance , but in this way the calculated modes have too low frequencies and too high dampings that is not correct (I have correct results for this model from someone who used another software). All the used values are appropriate to simulate squeal phenomenon and congruent compared to the respective units of measure. Does Optistruct allow to perform this kind of work?? If yes, could anyone help me, please?? Thanks Alberto
  7. Hello Rahul, thanks for the help. I have an update that could be useful for you: I also succeeded to create CGAP elements with the spotweld function that allows to create 1d elements from nodes to nodes. Now I'm having another problem: the results of the modal complex eigenvalue analysis are bad. If I use fixed slope approach (fixed stiffness K_t) for the frictional contact I obtain complex modes with too high dampings and too low frequencies; instead if I use elastic slip distance approach I obtain good dampings and frequencies, but all the complex modes are stable (real parts of eigenvalues are negative) even if i'm in squeal classical conditions. I tried to change lots of parameters like friction coefficients, number of roots desired (Both on EIGRL and EIGC cards to see if could be an effect of the modal method's truncation),etc. but I didn't obtain any good results. Do you have any suggestions on this situation?? Thanks very much
  8. Hello Rahul, I tried to remake CGAP elements on the model that you sent to me, but I didn't succeed. I varied all the commands in linear 1d like alignment,element config and density, but HM always gives back the same error!! In the image attached you can see it; the problem is that the mesh's elements orders are the same!!! Do you have any suggestion for solving this??
  9. Hello, do there exist any way to create CGAP elements automatically for the entire surface? Or I have to do it one by one?
  10. I have the same mesh on the two surfaces, so i think is a node to node connectivity. When I try to create CGAP l Can choose only from one node to another, instead I have to connect all the nodes of a surface to the nodes of the other surface.
  11. Hello Rahul. I'm setting up my model with the same approach of the example you attached here (brake_squeal_example.fem). I'm having troubles to create CGAP elements, especially to extend these elements to the entire surface where contact is present. Do there exist any tutorials about this topic? Otherwise do you have any suggestions? Thank you!
  12. Hello Rahul. I can use the full version on the PC of my referent professor at University. Thank very much for the support!!
  13. Hello Raul. Do you have any updates?? Thank You very much!