trac bars

[nwpadmax]

Sch80 is overkill, and allows Young's Moulus to factor into a failure mode sooner in the design & operating envelopes.

What? Explain that out...Young's modulus is fixed, based on the material.

 

[RJM06590]

Yeah all the bars I make are sch 40 and te biggest thing I make sure of is how the bracket on the axle is. I make sure that it's a 90 degree angle from the bar to the axle bracket so that you are putting all the pressure straight down the bar and not up in a way that would bend te bar. If you get a perfect 90 degree angle from the bar to the bracket you could use 1 1/2 exhaust tube and not have a problem because you just have a linear force down the tubing

Yeah the mount bracket was done well.

Actually, heims negate the necessity for 90* lever angles to generate pure compression loads.

His use bushings.^

 

[bna5017]

Maybe consider looking up some Column Buckling theories.. Where Young's modulus (modulus of elasticity) is a constant which depends on the material you are using (as stated by nwpadmax).

Also, moment of inertia (which is dependent on the I.D. and O.D., if you are making your bars out of round pipe), and length of the bars are critical factors that should be considered.. IMHO

 

[XLR8R]

Generally fixed, yes - but compressive strength (similiar to tensile for steel in regard to Young's) also must factor in shear, or buckling loads - that's why diameter trumps wall thickness up to the point of environmentally-caused stress risers... i.e. radiant exhaust heat expands 1/3rd of the tube's circumference enough to bend along the axis, or a rock dimple interrupts linear compression - tube folds like a cheap suit.

Long, skinny bars visibly sag in the center... usually doesn't end well.
I could stand on a straw if it'd stay straight!

 

[nwpadmax]

Maybe consider looking up some Column Buckling theories.. Where Young's modulus (modulus of elasticity) is a constant which depends on the material you are using (as stated by nwpadmax).

Also, moment of inertia (which is dependent on the I.D. and O.D., if you are making your bars out of round pipe), and length of the bars are critical factors that should be considered.. IMHO

Well, OK, better stated this time:

While E (Young's modulus) is fixed, XLR8R isn't making that exact point.

Most of the buckling and deflection equations are linear with respect to E, so when he says it "allows E to enter a failure mode sooner", that's what makes no sense to me.

Usually L is a dominant factor since it is often squared or cubed depending on which equations you're working with.

 

[XLR8R]

I'm all for better explanations... some nights I just don't sleep at Holiday Inn Express! :doh:

I've always been better at doing than teaching - but it's never stopped me from trying.

 

[bna5017]

Well, I only considered the critical load that would cause the bars to buckle, since that seemed to be the issue that the OP wanted to address. Which can be found using an equation that relies on length, modulus of elasticity, and moment of inertia.

 

[kypowerstroke]

yeah ok thats sum fancey talk, but i ended up takin the the track bars off and ruuning a stock tune