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Where has all the friction gone? devOLVED

Discussion in '3rd Party Add-ons' started by RCH_Projects, Apr 18, 2017.

  1. RCH_Projects

    RCH_Projects Alibre Super User

    Trying to finalize analysis of a model I am creating a "clean" simulation from scratch and applying all I've learned about Dynamics.

    But try as I might my friction has faded to oblivion. I especially use high friction (with a variable) to determine available torque - the end goal so to speak.
    I have used the original sim for a hundred variants this way.

    On this rebuild I have to push the values "orbital" to have effect.
    Maybe I have overlooked or forgotten a setting. Please take a look and advise.

    I created a new assembly with just a flywheel and axle, using an inserted torque (-10 ft. lbs.) to analyze and found no clue.

    Typically I have a coefficient of .8 and a 1.07 foot radius to slow things to a crawl.
    Coefficient 20 at 111,000 ft. to do the same seems a bit much.

    The part properties are set to coefficient of friction of .8 as well.

    I can't keep on this glitch indefinitely, care giving - so Thank you!

    Attached Files:

  2. RCH_Projects

    RCH_Projects Alibre Super User

    Re: Where has all the friction gone?

    Using a second flywheel with sim applied torque (-10 lbs.) and a belt constraint to flywheel-1, produces normal friction and torque results!

    Removing the torque from the second flywheel and placing it on flywheel-1 (the flywheel with friction and measured torque to shaft) only produces about 1/3 torque (and friction, based on rotation acceleration) now. That is better but far from acceptable and without explanation.

    Sim applied torque on a metered object has issues I suppose.

    The implication is that I should be able to get what I need with an extra flywheel in the target sim (although it is presently belted to a rotor????).
    The prior sims actually have such a relationship by luck, as the "second flywheel" was construed as a wheel.

    Success by luck/accident/trial and error/dogged determination? Awesome! :?: YMMV

    http://design-simulation.com/ Anything else I should know about? :shock:

    Attached Files:

  3. RCH_Projects

    RCH_Projects Alibre Super User

    Forget it - random success on slopware.
  4. listastudio

    listastudio Member

    I tried to download Your file to investigate it but it contains error and cannot be opened with actual build 9.85 of SimWise.
    Please try to post it again, ciao

  5. RCH_Projects

    RCH_Projects Alibre Super User

    "file contains error" ... ... ... ... ... hmmmm

    Dynamics 8.7, build 1336 - money ran out for maintenance - and ... ... ... here I am.

    I doubt if you can get there from here.
    I work with what I have, which could get me to what I need, which is what I want, if I can push through what I have.

    Would love to see error details for insight.
  6. RCH_Projects

    RCH_Projects Alibre Super User


    I downloaded the posted WM3 file and reopened.

    In friction I now find:


    That is crazy of course. "I" didn't do that, but I can see why it gave anyone an error! OH - I see, I tried an extreme value for "any" effect.

    I'll inspect original and post findings.
    Last edited: Jan 11, 2018
  7. RCH_Projects

    RCH_Projects Alibre Super User

    I have to take focus away a lot for care giving, and a lot for sim efforts. So If I step back from sim efforts it is because there is no stepping back from care giving. At 87 mother is getting the respectful care that she always deserved and her 4 legged, other loving companion is near terminal as well. This has gone on for about 15 years and usually I work after it is her "lights out" and I am practically never at my sharpest. My posts here are as much to help me track what does or may or may not work. That said;

    The initial effort posted was a return to "simulation 101" level. Getting stumped there is like applying the emergency break at 100 MPH on slick roads. I complain.

    I started over with the original assembly (same as zipped above) and recreated the sim file from scratch. It is only an anchored pulley shaft with a flywheel. Inserting torque on the flywheel or a revolute constraint, with variations in sim settings return no friction.

    As noted in a later post, it appears the mere difference in constraint orientation can cause unpredictable failures. At 19 I was a programmer analyst at Rice University ("The Ivory Tower of Evil"). I could take pseudo code and a memory dump and ferret out issues like this. Without that I can only isolate "hard error" by trial and error. A very long process.

    With nothing else to go on, please try to open this sim. It is a clean export from the "GeoMagic" as-is from the "Export to Dynamics..." menu, with no modifications. Please let me know if it opens cleanly.


    New Assembly (1).2.zip

    Attached Files:

  8. RCH_Projects

    RCH_Projects Alibre Super User

    5 downloads, no replies, dog dead...

    Bad week!
  9. RCH_Projects

    RCH_Projects Alibre Super User

    I should note that I need to know if any other version of Dynamics / Simwise can open the New Assembly (1).2.zi.p file above.
  10. Plista

    Plista Member

    To start with, there will be no friction force without a normal force acting on the joint.
    If I take the model (yes, it opens with SimWise 9.85) and turn on translational friction for the constraint, there is no effect because there is no normal force on the joint.
    As soon as I add a force that acts on the outer face of the disc, I get friction without any problem.
    Moreover I suggest You to rebuild the model, because if the CAD model is not assembled since the beginning with a simplified physical route, then the resulting automatic constraint mapping will show the full story of the CAD construction more than the physical working design, such as, several constraints built up instead of only one joint, the final result beeing the same of course but so easy to get lost with so many additional coords and axes and unuseful calculations!
    Unfortunately I do not have the possibility to regularly visit this CAD forum.
    I suspect that maybe among all the designers here, there are not many CAE specialists reading Your post, maybe only my two downloads (one was corrupted), out of the five You are reporting, were made for effective investigation and not for simple curiosity.
    Therefore, if You would like a prompt reply, my suggestion is for You to write directly to Design Simulation Technology at support@design-simulation.comfor faster and appropriate answers, since they are the developers of the code (and not Alibre LLC).
    I made available an Alibre model in http://www.simwise4d.it/SimWiseAlibreEN.htm if You woul like to replicate Yourself a case with SimWise4D instead of simply watching a movie.
    Please be free to report to support@design-simulation.com if You have additional questions.
    Last edited: Jan 21, 2018
  11. RCH_Projects

    RCH_Projects Alibre Super User

    :D :D :D :D :D :D :D :D :D
    Thank you for your reply Plista,

    That was the point of the (1).2.zip version of the file.

    It was unmodified output of the CAD to Dynamics translation.

    You could open it. That implies that it becomes incompatible when I modify it.
    You could set friction and add force and obtain friction. I cannot any way I try.
    So the CAD is valid - (yet incompatible with Dynamics).

    There are only two constraints in the CAD model.
    I can suppress neither, either or both CAD constraints (creating the constraint directly in Dynamics).
    Try a range of settings and I still no friction.
    What I cannot find is solid conditions that I can avoid to prevent incompatibility.

    It should have been the simplest model to trouble shoot.
    With an anchored axle and flywheel it can't get much simpler and be a simulation.
    But I will try it from scratch in CAD once more.

    I am afraid though that the failures are undefinable and forward file version compatibility is uncertain.

    I will try support@design-simulation.com but I am way out of maintenance and mostly cash.
    Worst case - going to other CAD boards where Simwise is used more widely (Alibre forum sighs with relief).

    One more favor, If you could post you settings and model so I might examine the entirety.
    The .WM3 file might come into my version as well.

  12. Plista

    Plista Member

    I would recommend You to download a trial of SimWise 4D v.9.85 from www.design-simulation.com and get 14 days of full functionality (including saving files) free of charge.
    Then You can check Your own cases without all the issues of using a software (Dynamics for Geomagic) which is not developed for dealing with newer files made with SimWise by myself (compatibility of course is only backwards) and even more from Alibre 2017.
    This way You do not lose time for unpredictable errors due to such a mix of versions and You do not pay anything.
    If after Your tests You will be happy, then I am sure Your dealer can offer You an attractive & discounted upgrade from the old Dynamic for Geomagic to the new SimWise for Alibre.
    Additional sample files for You to test with SimWise are posted in https://www.alibreforum.com/forum/index.php?threads/vibration-modes.16639/#post-126407
    Take care, Paolo
    Last edited: Jan 24, 2018
    RCH_Projects likes this.
  13. RCH_Projects

    RCH_Projects Alibre Super User

    I downloaded and run the "Mechanical Clamp - Completed.WM3" file without issue as a matter of fact.

    Runs like a champ.

    Friction added to the only revolute joint works (although I don't know how true the results are in my version - which is why I rely on the Sim software to begin with).

    I applaud the increased availability of contextual and quality video (http://www.simwise4d.it/SimWiseAlibreEN.htm) and FAQ. A LOT of issues have been addressed and a clear explanation of Alibre options are finally available. Otherwise the software is almost as straightforward as Alibre.

    Other great topics;
    "Coordinates" - how, when, why to swap, rotate, flip, relocate, etc..

    "Constraints" - selection of the base coordinate, splitting, swapping, joining and even deleting. One thing I (think) that I know, about deleting a Constraint, is to use the Coordinate Id's to go into the "Object list" and delete the Coordinates (which deletes the constraint) without leaving dead Coordinates laying around (my version?).

    "Contact" - characteristic dimension, overlap tolerance and steps relationship. I have studied "wire frame" mode for overlap insight but probably not my best topic.


    I am into speculative engineering and typical users don't jump the software through hoop like mine. My initial design goal is obtained (even by prima fascia objectivity) but passes through a brute force moment. The difficult, current refinements could simplify applicability broadly if proven. More "what have I got myself into this time" stuff. Even recrimination territory if I may say so.

    Your FEA plans are going to be "kicking it" (I attended a tech conference in Houston in the 80's; I found one CAD booth, with depressing ability; This is what has taken about 40 years to get to what I would find useful).


    If SimWise 4D v.9.85 doesn't install next to Dynamics that gets a little problematic.
    The Simwise - Alibre version, just excludes some extended tools that are beyond current needs, ability or finance.
    The real problem is I am on an old version (Geomagic) version of Alibre.

    Simwise4D means updating to current Alibre version with Alibre maintenance. A one way exit from Dynamics.
    Reasonable, otherwise I am sticking myself at difficult and unreasonable.
    Thanks for all of the assists, I will check options.

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