Modeling motion while designing living hinges

derek_ward

I'm curious if anyone has any experience designing with living hinges and simulating motion in assemblies with them in Onshape.  Any tips and tricks? 

romeograham

Interesting problem!
I have done this work in SW, but I'm sure you don't need that workflow here... However, I used the "Join" Feature to get the two parts back into a part from the assembly where the motion was defined. That feature isn't available in Onshape, but some type of in-context workflow might work.

Configurations
I think you could use configrations in Onshape: have a configured dimension that drives the relative angle of your two parts.You could have "open", "first contact" (where your seal first starts to inferfere or something) and "closed" or something Then your motion can be shown easily, and you can use a sweep, loft, extrude or other feature (that is robust enough to work in all positions) to create the hinge geometry.

Onshapes approach to configuration tables would make this quite easy.


References
Since both parts are in the same Part Studio, another tip would be to make sure that you have enough reference geometry (planes / sketches etc) tied to the moving side so that you can fully-define ALL the geometry of the moving part with respect to itself (not the non-moving geometry)...



Hope these suggestions help....if anything's not clear, I can put together some helper images later - just let me know.

Romeo

TimRice

I have done something similar before when I modeled a plastic water bottle. Follow the link below:


https://cad.onshape.com/documents/c3e9a2d66ff7fde0548ef0d9/w/de88b2b1ac4f4dfb9568109b/e/3965ead54c916dec25a64292

If you move the cap around in the assembly and then right click on the context and select "Update context" then the plastic connector will update as well.

derek_ward

@romeo_graham392, thank you for the workflow example!  

@TimRice, Thank you for the document share, but won't that change the dimensions of the living hinge when you move the cap around?  

TimRice

@derek_ward

Yes, I suppose so. I originally created the model more for fun and to try out in-context modeling than for accuracy.

derek_ward

I just wanted to provide an update to anyone interested in my quest for modeling living hinges in Onshape.  What I did isn't 100% ideal as it doesn't show the deformation of the living hinges, but at least it gave me an indication to how the connected parts moved in relation to one another.  Once I modeled my living hinges I simply split them in the middle with a Split feature and created multiple parts and used a Revolute mate to connect them (and then booleaned the parts when I wanted to export the final part).  It's as simple as that.  See my document here.  Thanks again everyone for their help and ideas!