Kinematics

ehsan_pazooki

Hello Guys,

How can I use sketch in onshape to simulate kinematic of some mechanisms like 4 bar linkage mechanism and it's movement?
I mean design and simulate the mechanism in such a way, that it will be possible to turn them and watch their movement just by using 2D sketch ?

Best regards

Ehsan

MichaelPascoe

Hi @ehsan_pazooki

It is possible to see the movement by dragging the sketch entities or changing the value of a variable that the sketch is using. However, it is not possible to animate sketches directly within a sketch, you would need an assembly. You can create configurations to see what the sketch will look like in position A or position B. For any of these processes, you will need to define your sketch with constraints and dimensions so that it works how you would expect it to. See the Introduction to Sketching course from the Onshape Learning Center.

eric_pesty

The best way to do this is probably to create your links in separate sketches (probably all referencing a "master" layout sketch), and insert and mate each of these sketches into an assembly. Like this:




Example assembly:
https://cad.onshape.com/documents/ddab4ba38e1d595bbe4f46db/w/a596e5381faff8863e0a14a0/e/526215e1aa4a0e81bfb7eab3

EvanReese

There's also a fairly old Four Bar Linkage feature that might help https://cad.onshape.com/documents/a2c6118153454c8ec8491c2b/v/c388b24d2381558687ee8fa9/e/59ab806000904029a1ec8dab?jumpToIndex=1018

ehsan_pazooki

MichaelPascoe
Hello Michael
Thank you soooooo much for your help and explenation
that was really helpful
is it also possible to draw automatically the motion path of the linkages? for example like in solidworks and GIM ?

Best Regards
Essi

ehsan_pazooki

eric_pesty

Hello Eric

Thank you soooooo much for your answer.
This is what I need.
But I'm a little bit confused.
How can I open such a 2D sketch that i draw in the tab "Part Studio" in a new "Assembly" tab ? to have the possibility to simulate the movement?
Could you please help me?
Maybe you can suggest me some pages with tutorials and explenation of what I need?

Thank you very much

Beste Regards
Essi

eric_pesty

@ehsan_pazooki
If you look at the link in my post, you should be able to see what I did (you can make a copy of the document to be able to edit it). All you need to do is insert the sketches in the assembly as if they were part).




You won't be able to automatically trace the continuous motion but you there are a few ways you can visualize the result directly in the part studio.



Edit to add: it takes a bit of work but you can manually "plot" the motion using configurations/in-context:

https://cad.onshape.com/documents/ddab4ba38e1d595bbe4f46db/w/a596e5381faff8863e0a14a0/e/5895ad9c9dd4c40a5b1c1609?configuration=Increment=0.7853981633974483+radian;StartAngle=0.0+radian;Z_spacing=0.050800000000000005+meter&renderMode=0&uiState=63d0854cb70aee25b9bdd7fc

ehsan_pazooki

@ Evan_Reese

Thank you so much
It's a cool feature
Are there some similar feature for other types of mechanisms ?
For example crank rocker, crank slide and so on?

Best Regards
Essi