[vex]

Originally Posted by sofaking

Vex...


Note how the application of laws AND MATHEMATICS are used to model and derive real world outcomes? You're refusing to do the math under the premise that you're right? Prove it. As for thinking you're so intelligent that I wouldn't understand the math because I'm somehow beneath you for not going to the same classes as you in college? Jumping to conclusions again. I can't write programming for shit either, but it doesn't mean when a program isn't working I can't look at the code and see flaws in it. That doesn't mean I can program from scratch though.

Holy shit. Do you know how uneducated you sound when you typed that? Here's some sample FEA, tell me if it's going to fail:





Look up spring mass damper systems if you're a little hard pressed to understand. From there pick this book up:
http://www.amazon.com/Deformable-Bod...662630&sr=1-10

Once you understand those we'll have something to discuss.

The part I don't get is how you still can't understand that without the math you're speculating based on your understanding of the materials. YES, IT IS WEAKER. NO, THAT DOESN'T MEAN IT WILL BREAK. The math is what ties your your information about the materials to the theory that it is unsafe or will break. Without the math, you're talking theory.

There is not a face palm big enough for what you just typed.

If you want to argue dick size or IQ I've got enough of both. I'm not trying to argue that, I'm trying to argue that you can't stamp something as a fact without testing it or doing anything to prove it. I can cut through your BS and see that you aren't willing to do the math because of one of 2 options, 1) you don't know how (which based on your line of work I'd imagine you probably have the formulas) or 2) you're afraid that the math might give me more to argue with.

Apparently not, but your foot size sure seems sufficient to keep putting in your mouth.

I understand the laziness factor; I wouldn't want to do 1-4 hours of math either to prove a point. But without it you're speculating. If you just admit that without the math you're speculating, then we can move on. As someone in the field of this type of mathematics I would venture to say that if you can't admit the math ties your premise to facts then I wouldn't imagine you're very good at your job. It's cool, some engineers get into the field because they heard there is money in it, not because they're naturally good at it.

Do you need to do math to understand a weaker material is present based on geometry? Nope. Do you need to do the math to tell you a material is an insulator or a conductor? Nope. Your argument is a logical fallacy.

Oh as for your question, I'm not sure what you're looking for here so I'll just list some stuff off the top of my head and let me know if I'm close to what you're looking for...

We'll work with what you posted.

Tire pressure, weight on the particular wheel/tire,

Yes

temperature of all materials and outside temperature,

Are not forces and are not needed for a preliminary analysis

what the tires are filled with (nitrogen, air, helium),

Again not really needed, but good to know.

The stretch of the tire (still an inch and 1/2 of difference between the recommended wheel widths for a given tire without being outside of spec),

This confuses me a little. Are you saying preload of the tires deflection?

the materials used for the wheel and tire,

Yes

and camber.

Yes, but only dictates the location of the force acting on the tire.

Once in motion I would guess...
friction,

Okay, how are you going to calculate that force? Static friction, dynamic friction, all are based of the weight of the wheel in question. Furthermore different compounds have different friction values.

shock/spring combination,

Only matters if you're doing an unsteady deformation analysis (which isn't even done for rocket engines)

lateral forces

Then it's not exactly 2D is it, but for 3D analysis is spot on.

and additional compression from the various loads during cornering,

Which are... what exactly?

braking,

Again, dynamic, but not really needed for preliminary analysis.

acceleration,

Is not a force.

bumps in the road,

Is not a force.

wheel/tire balance, toe, and caster.

Only needed for 3D analysis.

I'm sure you'll find something I missed, but that's a basic list of shit off the top of my head.

Which has basics of it, but are not everything we need. I'm keeping it simple for your benefit.

I really can't understand why it's so hard to admit that mathematics is required to prove your point. Without it the only thing that you can say for a fact is that the tire is weaker, weaker =/= failure or unsafe.

Nor have I intimated it as such. I have stated that deforming a tire outside of manufactures spec prior to normal driving forces will weaken the tire. The difference is do you know how much weaker the tire has become? The obvious answer through your posts is of course, no; you do not.

Now that we have a rough idea of forces I'm going to ask you to draw a picture. Draw a circle. This circle is representative of a tire. Draw the forces on that tire. (I'm thinking of the view you'd get if you looked at a tire from the side) Draw the forces for friction, weight, pressure, etc.

In determining the stress levels we have to use statics (unless you want to do dynamic analysis which is a whole bunch of worms worse than what you think is possible). That means, application of the forces must result in 0 displacement of the body--or the body must undergo stress to maintain unity. But that's getting ahead of ourselves. Lets keep it simple.

Draw a circle and place those forces you've described.


(Just for future reference:
In mathematics, a proof is a convincing demonstration (within the accepted standards of the field) that some mathematical statement is necessarily true. Proofs are obtained from deductive reasoning, rather than from inductive or empirical arguments. That is, a proof must demonstrate that a statement is true in all cases, without a single exception. An unproven proposition that is believed to be true is known as a conjecture.)