Welcome to the Onshape forum! Ask questions and join in the discussions about everything Onshape, CAD, maker project and design.

First time visiting? Here are some places to start:

  1. Looking for a certain topic? Check out the categories filter or use Search (upper right).
  2. Need support? Ask a question to our Community Support category.
  3. Please submit support tickets for bugs but you can request improvements in the Product Feedback category.
  4. Be respectful, on topic and if you see a problem, Flag it.

If you would like to contact our Community Manager personally, feel free to send a private message or an email.

FEA simulation? for " O-RINGS" "not what I want"

stephen_normylestephen_normyle Member Posts: 3
edited July 14 in Community Support
Creating an O-Ring is a very simple task as well Creating O-Ring grooves I used an O-Ring Calculator to verify tolerances and fluid type this calculator is really easy to use http://www.applerubber.com/oring-gland-calculator 
anyway I just don't believe an o-ring with a material spec of  Silicon Rubber against 6061 aluminum can't be spec'd to 
compress instead of just passing right into the 6061. if the parameters of the material could be changed to dynamic within its self and against other objects that would be amazing..  
During the "Squish" of the O-Ring the sides expand equally in the groove based on the total amount of compression  applied.
The O-Ring i'm using is a 1 x 3 x 5 (t, id, od) or (dimensions) (thickness) (inside diameter) (outside diameter)  = .039  x .118 x .195, total Squish = .012 which translates to .003 on each side of the O-Ring in the groove,  forces from the id and the outside diameter are combined which is .006 each for a total of .012 / 4 = 3 the groove is .124 and the bore is .186  and groove width is .054 so imagine an ellipse if you will once compressed I realize anFEA Simulator would show potential flaws, I don't have that problem... I want those O-Ring to Squeeze into the bore and expand when released when animated.. I know I can make them elliptical.. That's not what I want to do, it's great for a picture just not great for a demonstration video..
Thanks in advance
Stephen Normyle (COWBOY) 


Answers

  • NeilCookeNeilCooke Moderator, Onshape Employees Posts: 968
    edited July 15
    You need a non-linear transient analysis. Take a look at some of our partner apps. 
    Neil Cooke, Director of Technical Marketing, Onshape Inc.
  • joe_dunnejoe_dunne Onshape Employees, Developers Posts: 103
    Typically to animate this behavior for illustrative purposes, you would use some kind of keyframe animation tool. Clara.io will allow you to keyframe this deformation from circular to squished. 

    While you could use FEA for a very accurate shape. That seems like overkill. It would require a high end tool. Something like multi physics product will do this.  

    You could also model the xsection of the oring with a ellipse in Onshape. Then using the H and W values of the ellipse you can then change the values from squished  to a circle... a before and after.


    Joe Dunne / Onshape, Inc.
  • philip_thomasphilip_thomas Member, Onshape Employees, Developers Posts: 645
    edited July 17


    While this isn't exactly what you asked for - many people read these threads and some may be interested to learn that there is a public custom feature that will create 'squashed' O rings - preventing them from showing up as 'interfering' parts.


    https://cad.onshape.com/documents/57896d4ee4b0f979c401da20/w/25dc73fef97a652c054ee6e1/e/8817b266f99342c53037c3a0





    Philip Thomas - Onshape
  • stephen_normylestephen_normyle Member Posts: 3
    I'm assuming the Public Feature is a script? I did look at the ?DRUM? and that's about all I could do with it

  • stephen_normylestephen_normyle Member Posts: 3
    Thank you Guy's, I did change the shape to and ellipse and now no crashing, I don't understand what Joe is saying about using H & W before and after? During animation or screen shots? Also I figured out how to make a TORX  T-8 & T-10 recess among many other things. Onshape has got me hooked, I love it, I came from Generic CADD 6.1 and never took to Auto-Cad and am totally self trained... a long time ago.. lol
    Thanks: Neil, Joe and Phillip
  • philip_thomasphilip_thomas Member, Onshape Employees, Developers Posts: 645
    @stephen_normyle - A custom feature is a feature written in the same language that our developers use to create the native features in Onshape. When you use a custom feature, it is a first class citizen (meaning that it behaves like any native feature) and will always work moving forwards. You are free to write your own (to help you we have open sourced our source code - see the link below) as well as use those written by others (many are public documents). There is a reference for you here with a collection to get you started and some learning and reference materials.  https://www.onshape.com/customfeatures.

    Have fun :)


    Philip Thomas - Onshape
Sign In or Register to comment.