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CAD Springs

CAD Springs

CAD Springs

As a part of a project I was involved with, I was asked to do a suspension model in CAD package, and it had to 'look nice', and that it can be 'played with'. So I tasked myself with doing things properly and with little effort did better than was expected of me...

Using the wonders of parametric design in modern CAD software (CATIA v5r19, to be more precise), not only did I manage to make a decent shock absorber mock-up with adjustable spring perch, but even a coil spring that could be compressed and extended as one pleases (with no distortions and deformations)... So, basically I made a coil-over (sub)assembly which reads it's own length and compresses the spring accordingly. (OK, admiteddly it's nothing useful, but unlike 'solid' springs one can easily model it allows the suspension to move and looks purdy)

If anyone here likes to fiddle with CAD models, or even does that for a living*, I'm perfectly willing to dig out the files from where I've buried them and make them available to anyone who pleases.

* if it makes your bosses happy ad it did mine- you can even say you made it yourself, I won't mind

RE: CAD Springs

"but even a coil spring that could be compressed and extended as one pleases"

how did you make that, if you don't mind me asking? can you explain please, how did you make it deformable (compressable)? i suppose that it can be used for an animation?
would you mind posting it here or sending it to bainit1_yahoo.co.uk
replace the _ with @.

many thanks.

RE: CAD Springs

Loki, it's quite simple actually-  had more trrouble making the springs the way they should look than making them deformable. It's just parametrization of definiton of the helix that defines the spring. I'll attach the file (CATIA v5r19), but if You can't open it, here's a simple explanation.

Parameters that I've used to define the spring are free length, tavel, inner diameter, wire diameter, spring length, and (just for fun of it, stiffness). Number of coils is then calculated, and along with other parameters used to define the helix- starting point is 1/4 of wire dia behind ref. plane and height is current length + 1/2 wire dia, pitch is height / no. of coils. Once the spring is created as a rib of wire profile, ends are 'ground' by intersecting it with a box of correct length. (well, I might have done 'grounding' in a bit more elegant way, but it works) I was a bit lazy, because it's very simple to make a catalog part of the spring (with a design table, but I couldn't be bothered to type in the whole range of e.g. Eibach or KW racing springs).

The use is quite simple- once you insert it in assembly (presumably coil-over), make a formula in assembly to control the current length parameter (say, measure distance between spring seats). If you're interested, I could upload the whole coil-over assembly tomorrow (it seems I have moved it around too much and something got messed up).

If it's of any interest, here's a pic showing it working in suspension assembly: http://imageshack.us/photo/my-images/687/suspn.jpg/ .

RE: CAD Springs

are you able to move the asm as you see fit and the spring deforms with it? if yes, then i understand. you set the distance between the two fixtures of the spring as the total length of the spring in the eq.

RE: CAD Springs

Yes, exactly- you set damper constraints, and formula within damper assembly controls the length of the spring.

I'm off for the weekend, so I'll post the whole coil-over assembly, ready for installing in the suspension. One can adjust the angle of top eyes and distance between top eye and spring perch.

[telemarketing mode]And if you download now, you will not only get a damper and a spring, we'll throw in a spring perch, counter ring and bump rubber for free! But it's not all- we'll also include intermediate ring in case you wish to install a helper spring! And all this for amazing price you see on your screen![/telemarketing mode]


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