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So I cannot figure out where my math is going wrong on chassis rigidity test. All I am trying to do is figure out the lbs/deg.

going off this
http://waset.org/publications/3660/the- ... nt-formula

A load of 316lbs was applied 53" from the fulcrum and the dial indicator moved .3" here is the setup (this isn't the chassis under test though).



Torque (L*w) would be = 53" (4.416ft) * 316lbs = 1395ftlbs
Angle archtan(w/L) = tan-1(.3/4.416) = .0678
Torsion = T/Θ = 1395/.067 = 20575ftlbs/deg

Am i missing another dial indicator?? Or am i really screwing up the units?

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My build: http://www.locostusa.com/forums/viewtop ... 18&t=13096


You can build the most awesome thing in the world but at some point, an 80yr old man in a crx is probably going kick your butt on the track... don't ask me how I know.

.3"/53" in angle calc if you measured deflection at point of load application

not following...

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My build: http://www.locostusa.com/forums/viewtop ... 18&t=13096


You can build the most awesome thing in the world but at some point, an 80yr old man in a crx is probably going kick your butt on the track... don't ask me how I know.

you used .3 inches/ 4.416 feet

right! but that makes the chassis even more rigid @ 279000ftlbs! It doesn't add up...

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My build: http://www.locostusa.com/forums/viewtop ... 18&t=13096


You can build the most awesome thing in the world but at some point, an 80yr old man in a crx is probably going kick your butt on the track... don't ask me how I know.

no, angle is factor of 12 greater thereby reducing stiffness to 4301 ft-lb/degree

bahhhh still not following.

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My build: http://www.locostusa.com/forums/viewtop ... 18&t=13096


You can build the most awesome thing in the world but at some point, an 80yr old man in a crx is probably going kick your butt on the track... don't ask me how I know.

wait my calculator is in radians!! damn it fancy calculator!

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My build: http://www.locostusa.com/forums/viewtop ... 18&t=13096


You can build the most awesome thing in the world but at some point, an 80yr old man in a crx is probably going kick your butt on the track... don't ask me how I know.

You can't divide inches by feet. If you're doing ft-lb/deg, you need to convert your .3" into feet, then try again.

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-Justin

"Orville Wright did not have a pilots license." - Gordon MacKenzie

so 4305 isnt right?

Angle archtan(w/L) = tan-1(.3/53) = .324
Torsion = T/Θ = 1395/.324 = 4305ftlbs/deg

_________________
My build: http://www.locostusa.com/forums/viewtop ... 18&t=13096


You can build the most awesome thing in the world but at some point, an 80yr old man in a crx is probably going kick your butt on the track... don't ask me how I know.

Yes, inches and inches works for the degree calculation too. It's just easiest to not make mistakes if your work is all in the units of measure used by your desired output.

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-Justin

"Orville Wright did not have a pilots license." - Gordon MacKenzie

Correct or have the calculator set up wrong. Now I just need the simulation to match what we just measured in the real world.

_________________
My build: http://www.locostusa.com/forums/viewtop ... 18&t=13096


You can build the most awesome thing in the world but at some point, an 80yr old man in a crx is probably going kick your butt on the track... don't ask me how I know.

...Or both.

_________________
-Justin

"Orville Wright did not have a pilots license." - Gordon MacKenzie

Cool the chassis we tested ended up having a torsional rigidity of 2480ftlbs/deg.

_________________
My build: http://www.locostusa.com/forums/viewtop ... 18&t=13096


You can build the most awesome thing in the world but at some point, an 80yr old man in a crx is probably going kick your butt on the track... don't ask me how I know.

Did you apply the loads and constraints through the coilover mounts?

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