living hinge simulation?

greets all --
quick question .. just an 'exercise' as I don't really
need to do this (or have to-date).

say you've modeled a plastic box with lid attached in
the open position with a living hinge -- how could one
(if its possible) close the box (bending the hinge) to
check if it works geometrically (ie your hinge isn't too
short, for example).

I can imagine doing this as an assembly with the hinge
built in-place -- but the box here would always close
(since the in-context hinge would update accordingly).

not looking for an animation or 'simulation' -- just
something like a visual geometric failure .. for example
the outside surface of the hinge penetrates the inside
surface when it folds closed.

-Tony

 

Good question, and I've done it and designed a half dozen or more
hinges.

I have used assemblies with different configurations to represent the
hinge as a separate part and that works OK.

I have also designed a solid where the hinge has a slight radius &
angle, and I dimension the curvature and neutral axis, to allow the
hinge to have the bend angle changed. The problem comes with, say,
the lid. The lid has to be designed to be entirely constrained to the
end of the hinge. This means you can't use any references to
horizontal or vertical or another fixed plane, as then the lid won't
"move" when the angle of the hinge is modified.

I personally think it would be terrific if SolidWorks would implement
a feature allowing a flat or curved section to be bent and allow one
side of the model to move with it, but I know this would cause a lot
of exceptions to be made, so I don't know if it would work or be
worthwhile.

I'll probably stick to my existing methods.

 

Tony,

This article might help: http://designsmarter.typepad.com/gabijack/2008/05/flexes-hexes-an.html


Matt Lorono
http://sw.fcsuper.com
http://ww.fcsuper.com/swblog

 

Perfect. Cursory scan looks very interesting --
will work through it shortly.

Now I'm wondering exactly what the Flex command
does (geometrically) -- I'll try it perhaps measuring
a few cross sections to see where/how Flex does
its magic and if the mechanism is close enough
to "real world".

Thanks again.

-Tony

 

Matt, I've ignored Flex, because of my own limited time and lack of
classes. I'll definitely have to take a look and see if I can make
something work.

One of my designs is what I might refer to as a molded "fold up box".
To make an "assembly" shape, I will have to be able to have multiple
hinges "Flex" simultaneously without disrupting each other. I'll have
to try that first with a simple flat strip with three hinges to see if
I can make a basic square shape when 3 hinges are folded.

Thanks Much - Bo

 

Matt, I can see that Flex is simply impossible to use in the real
world of multi-hinged products.

Bo

 

Bo,

Well, I was just suggesting reading to Post to see if he could use
it. I don't claim it to be a final answer to anything.

Matt

 

Thanks much for the suggestion. I hadn't looked at the Flex command
for a long long time. I need to keep up with more of the tools than I
routinely use. The open up options I don't know about, if I don't
just try things for learning now and then.

Thanks - Bo