Wishbones

[Tommer 0]

*registers interest in 309 bones*

[Rippthrough 98]

Good man.

 

Isn't that a bit excessive though? Surely you could save more weight and a bit of machining time by having thin walled steel and machined threaded plugs?

 

Nah, they're gunndrilled down the centre, link weighs in less than 100 grams, you wouldn't get one much lighter...

 

Im planning on fitting standard mounts to my comp brake wishbones and iv was advised to used hollowed out bar as a apposed to seamed tube, however alot of the locost cars use the latter technique but being much lighter have less stress, and its cheaper...

 

Paul

 

We use CDS on the safari cars, they see 10x the stress even most rally cars do...

[M_R_205 5 1 Cars]

We use CDS on the safari cars, they see 10x the stress even most rally cars do...

 

Hmm, im not sure why i didnt think of that... what a pillock!

[wracing 19]

Rippthrough have you got some serious sponsorship or I very deep back pocket. you seam to have some very nice bits of kit!!

 

Ill have to look into the prices for cds and the wall size availability.

 

James

[Rippthrough 98]

Actually most of my stuff has been done on a shoestring.

 

I just daren't start adding my labour up...

[wracing 19]

I know the feeling!!

 

James

[Rippthrough 98]

I know the feeling!!

 

James

 

And add that and that, and just carry that over annndddd....

 

...Fook, I could have bought a Veyron...

[Capn. Pugwash 0]

I'm keen on a set of 205 wishbones if the build goes ahead Is the plan to use spherical joints to replace the inboard bushes as well as the balljoint or can I make up some poly bushes instead?

 

Sorry for the dumb question, but will I need to weld my hubs up if I'm not using the pinch bolt balljoint system? I bent the pinchbolt like a banana in the last rally and am fed up with chewing through balljoints and bushes!

[Liquid_106 97 1 Cars]

I'm keen on a set of 205 wishbones if the build goes ahead Is the plan to use spherical joints to replace the inboard bushes as well as the balljoint or can I make up some poly bushes instead?

 

Sorry for the dumb question, but will I need to weld my hubs up if I'm not using the pinch bolt balljoint system? I bent the pinchbolt like a banana in the last rally and am fed up with chewing through balljoints and bushes!

I think the plan is to use a 306 BBJ so it's easily replaced and original mounting method so that original pug or poly bushes can be used.

 

Hope this goes ahead

[Baz 421]

I hate to bring a dampener, and can't believe it's not been said already, and it's a shame it has to be, but in this day and age with our 'blame culture', you have to forward think everything.

 

So if these are made and in a worst case scenario, who's liable? Or do you make everyone sign thier life away in a waiver/agreement etc?

Edited May 10, 2010 by Baz

[wracing 19]

If I ever passed this on they would be sold as a Peugeot 205 wishbone wall bracket

[Cameron 16]

I'd just put a general waiver on them that the buyer accepts through ordering a set. Something like: although every attempt has been made to consider all potential failures, the buyer agrees that without the limitless research and development budget of OEM's it may be possible for some circumstances to arise that could cause damage or failure. The buyer accepts this risk at the time of purchase and with the exception of negligence on behalf of the designer, accepts responsibility for damage or failure of the part and any damage or injury caused as a result.

 

Basically, people buying these need to accept that James cannot realistically account for failures caused by excessive abuse or improper fitting of the parts. You can't really account for fatigue either without destructive testing but you can account for it in the design. Having to do either would drive the cost up as the time invested increases massively, so in order to keep the cost down the buyers must agree that with prototype parts (which these essentially are) there is a risk of failure. However the buyers are all agreeing to accept this risk because of the reduced price.

Edited May 10, 2010 by Cameron

[wracing 19]

Right a little bit of a follow up, most of the images a meaningless as of yet, but im just experimenting with different designs, looking at various loadings and weaknesses.

 

Ignore the massive amount of displacement i'm running massive loadings to begin with

 

I'm using cosmosexpress to start with to save a bit on cpu time. more pics to come throughout the day

 

 

 

 

 

 

I've run these simulations with a 5000N loading on the end of the bone. Im not quite happy with the design just yet still playing around

 

Open to suggestions

 

James

Edited May 16, 2010 by wracing

[Cameron 16]

Looks pretty good, can you display the results in 1:1 scale? People may get freaked out by those pics even though the scale is 90:1!

 

Edit:

A quick tip, put a small radius where the inboard mounts join the pain part, it looks like you have a sharp edge there at the moment that is acting as a stress raiser.

Edited May 16, 2010 by Cameron

[wracing 19]

Agreed the next stage that I'm working on has 25mm radii on the inboard joints, im just trying to work through the design optimising each weakness flaw.

 

Good point the displacement at full loading is like 0.32mm ad not the 100mm odd shown

 

 

James

[wildejon 7]

Let me know if you want any CFD done

Not sure it is really relevant considering where it is positioned mind you.

[wracing 19]

I think we are getting there, please ignore the twisted wishbones, I cant edit the deformation scales on the version I'm using at the moment.

 

We are talking under 0.25mm flex under the hardest braking (5000N loading) which is very good indeed. and a safety factors of around 2.2 operating nowhere near the yield strength of the mild steel these wishbones will be made from.

 

Im looking into some more exotic materials to make a lighter design, as at the moment we have a all in weight of 3.4Kg.

 

 

 

I need to sort the loading shown in the above picture.

 

James

[All Praise The GTI 3]

good work mate keep at it

[Cameron 16]

Have you got any other FEA programs?

[wracing 19]

Soildworks simulation professional, I'm just using the express as its nice and quick, only on a quad core ill post final pass FEA results once i'm done.

 

Do you think that stressed point will disappear when using another application?

 

James

[Cameron 16]

I don't know, it's not that clear how you've restrained it. Was the restraint applied to the inner surface of that hole, or to the edge?

 

I've never used either of those applications so I'm not sure how their restraints work, Solidworks could be similar to Catia though.

[wracing 19]

I've dabbled with catia and they seam very similar i read somewhere that they were based around the same engine, how true I'm not sure.

 

Its constrained on both inner holes (faces). i really need to add a bolt and draw the bush correctly before messing around to much.

 

I have had a quick look at your tubular wishbone project, you seam to have simulated with the same sort of forces, what safety factor where you aiming for? due to the nature of the component, you can never quite calculate every loading

 

Thanks

 

James

[Cameron 16]

Yeah Solidworks and Catia are both made by the same company, from using the SW CAD program it's almost identical to Catia except for the names of the functions and some functions which are slightly more basic.

 

You could try replacing the fixed support on those inner faces with some friction-less surface support, then adding similar supports to the outer faces. That would be a slightly better representation of the way they're restrained on the car.

 

I think the later designs were getting safety factors of around 2, but I was seeing some petty high stresses in the inboard rear rod end that threw the results out. I think a safety factor of 2 is pretty reasonable, you should be seeing less load than you've calculated because a fair bit of the braking and cornering forces are taken by the strut.

Edited May 17, 2010 by Cameron