Adjustable Blade Anti-Sway Arms ???

[Norm Peterson]

Are we talking about active or partially active suspension, with an actuator at each corner?

I would think that a linear actuator would have a relatively fixed stiffness but a wide range of possible positions. Assuming that you have some way of controlling the positions of the LA's, you'd attach them directly to the chassis and make them responsible for limiting roll. You wouldn't then need any part of a sta-bar at that end.


Norm

[Bryce]

Actually what i was thinking was to use a linear actuator for the sway bar arm (connection between the end link and the torsion bar) this would be able to vary the length of the arm and therefore vary the spring rate of the torsion bar.

k=P*M/deg

k is the spring constant of the bar

P is the force applied and this will be proportional to the body roll

deg is the rotaion and again proportional to the body roll

M is the length of the arm (moment arm) this is what would be driver adjusts from the cockpit. the linear actuator.

[Norm Peterson]

I guess that would be do-able, if somewhat heavier and bulkier. Keep in mind that every additional piece in the load path along the bar that isn't firmly attached to some other piece is a potential location for lost motion, more so if wear develops between separate arm pieces courtesy of shear and bending loads. I would hope that placing threads in bending isn't being considered.


Norm

[greencactus3]

didnt know about this thread, havent read the whole thing but im in the middle of designing one for our fsae car currently

leafs are going to be Ti (stuff we had laying around so dont know what kind) and 4130 for cups and tubes.

we made a test piece and used weights and dial indicators to test if simple tubes in torsion and beams in bending calculations will be applicable or not.... turns out not really..
especially the leaf is hard to model/design with pure static equations.
(lots of assumptions had to be made)

so if you really want to get a blade style arb setup to work the way you want it, i recommend making 1, testing, redesign, repeat.

btw, watch those stress calculations too.

[David Pozzi]

Ralt pioneered the use of blade adjusters with constrained ends to prevent side to side deflection of the end links. He built guides to restrict any side to side movement.

In your testing, have you seen this happen?
David

[911industries]

I tried to read most of your posts so I understood the conversation. You guys can really go off.

My situation is I need sway bars on my car and since I dont want to spend a grand on kits I need to make them. Can I use chromoly to make a predictable swaybar? I was thinking around 1" x .085. 4130 is common chromoly right? I know moly has spring to it but will it spring back to its original position when used as a sway bar?

My guess is the bar will be just over 30" and twist 1/8" with full articulation. I want to use tubing for weight and moly for availability.

Next topic. This is the first time I've heard of blades for the arms. In my case these would be nice considering my rear bar will most likely be inside the car with small holes for the connector links. Now what type of steel would the links be made of? Also as you rotate the blades wont they gain a certain amount of sideways deflection?

I just realized Im only on page one of the posts. I hope these questions werent already answered.

[Norm Peterson]

OE Tubular bars are typically made from tubing where the wall thickness is about 15% of the OD.


Norm

[911industries]

So, if I chose a 1" tube it would need to be .150 thick. The thing is I'm not talking about OE bars. I want to buy steel from my local dealer that will work. Do you know if moly will hold up?

In my mind 1"x0.125 seems like it would take the stress. I havent checked what is available or available for a reasonble price yet.

Basically what I want to know is my options on tube that I can buy to use for a sway bar.

[Norm Peterson]

I figure that the OE's have settled on 15% with the benefit of much more detailed analytical methods and a lot more actual experience. That said, 1/8" has a much better chance than 14-gauge.

Don't overlook bending loads, shear, combined stress, and buckling. The central portion is generally NOT loaded in pure torsion.


Have you checked out the circle track supply houses? I know you can get tubular torsion sections in a variety of stiffness and the arms separately.


Norm