Roll Cage material ?

[Richie]

that's the plan, i have a suzuki 50cc... somebody put regular 30 wieght oil in it, i have since drained and replaced with 2 stroke oil, but i can't seem to keep it running... i'm thinkin a carb rebuild is what's needed, once i get it runnin i can get back on track and begin some test's

[manta22]

Once I read a structures book that refered to bent tubing as "pre-buckeled" tubing--- a good point, I think. However, so as not to create a problem in tech, my roll cage is all bent round tubing.

Regards, Neil   (Ouray, CO)

[Peter Jack]

For equal cross sections and wall thicknesses round is lighter and stronger in torsion while square is heavier and stronger in bending. It would be very difficult to get a satisfactory wrinkle free bend in square tubing for roll cage construction.

Pete

[Richie]

 author=Anvil* link=topic=10147.msg166489#msg166489 date=1312834954]
I think it's best to consider this a mock-up.

That said, I would complete more of the build (but don't skin it) and maybe think of plunking a stock engine in it if you think the layout is going well.


I most likely will skin it with sum flat plate... atleast the area around the driver , also was thinking bout puttin a training wheel (sidecar)
on it cause, i will be starting of at a slow speed

[Richie]

Another reason i was thinkin aluminum was when i seen this pic i thought that was aluminum tubing... after lookin at pics on chevyasylum  i realized it was steel, just wonderin what size tubing?

 Awesome bikeliner

[Peter Jack]

Unfortunately that lying forward style liner has been made illegal, at least for now.

Pete

[Richie]

 author=Peter Jack link=topic=10147.msg166656#msg166656 date=1312944735]
Unfortunately that lying forward style liner has been made illegal, at least for now.

Pete


makes ya wonder why , seems it has proven to work

[old chevy truck]

The original question from richie asked if square tubing could be used to construct a roll cage.

I think DW implied that it could. I don't think it can.

In fact section 3.B.1, in the first sentence requires the use of ".... 1 5/8" O.D. round steel tubing..." for all roll cages class down to the F class. Starting with  the G class and below the requirement is "...round steel tubing not less than 1-1/2 in. O.D..."

Look pretty clear to me.

[jimmy six]

Many of the really fast big diesel truck roll cages have been constructed of square tubing. I'm sure they are thicker than .120"; perhaps as thick as 5/16". Many of the faster lakesters and liners also have square tubing under the driver which is considered part of the cage system. My advice would be to prove the strength of what you want to do to the technical committee prior to making the commitment to do it...............Good luck

[Interested Observer]

Ref:  Reply #32

However strong Pete’s conviction is that round tubulars of the same outside dimension and thickness as a square cross-section have better torsional capacity than the square, it would be remiss not to point out that that point of view is in conflict with established engineering practice.

For a closed, thin-wall tube of any shape, the torsional capacity, to a close approximation, is proportional to the area bounded by the centerline of the wall thickness.  So, in the case of the 1-5/8 x .125 wall round vs. square tube, the ratio of the square’s area to the round’s is 4/(pi) or 1.27.  Square wins again, but that is not to say it may be the best or allowable choice for a roll bar.
 
(See “shear flow” in any Strength of Materials textbook.)

[Richie]

 author=old chevy truck link=topic=10147.msg166662#msg166662 date=1312950480]
The original question from richie asked if square tubing could be used to construct a roll cage.

In fact section 3.B.1, in the first sentence requires the use of ".... 1 5/8" O.D. round steel tubing..." for all roll cages class down to the F class. Starting with  the G class and below the requirement is "...round steel tubing not less than 1-1/2 in. O.D..."


Bub rules state , 1 1/4" x .090 does not specify round or sqaure... highlights no aluminumn hardware as part of the belt system,but does state this Builders of any frame other than those constructed of steel shall submit frame structure information to the promoters that document the durability of the structure. When requested, provide test certifications on components and stress examination as required.?

[Peter Jack]

Thanks IO. I'll go digging a little deeper. That's one I've had locked in my mind for a long time. I can't remember the source but now I'll go looking further. Don't want to be dispensing inaccurate information.

Pete

[johnneilson]

IO, All,

yes, I goofed reading the results, I miss read the Deformation scale for the displacement.

I really need to wear my glasses more and pay attention.

I am not really sure if the picture attached would have survived better being round tubing or not.
My immediate thought would be to increase the wall thickness and stop sliding into k rails sideways........

FWIW, IO had the numbers pretty spot on for displacement, and correct, overloaded to the point of ridiculous.

J

[Richie]

 author=johnneilson link=topic=10147.msg166370#msg166370 date=1312753619]




could you perform the test this way?

[johnneilson]

here you go, same model with centered force@ #1000

these plots show the displacement of the center point.