Wheel loading scenarios

[mgomezz116]

Hey my team is thinking about making custom wheels this year. Our plan was to start with modeling the current wheels, then preform FEA on the model to see what kind of strength the stock rim had. From there we would try to match the new design to the stiffness/strength of the old.

My question is this: what kind of loading scenarios should we be looking at? And by this I mostly mean what magnitudes and distributions should be considered.

Any thoughts on this topic would be helpful.

[mgomezz116]

Hey my team is thinking about making custom wheels this year. Our plan was to start with modeling the current wheels, then preform FEA on the model to see what kind of strength the stock rim had. From there we would try to match the new design to the stiffness/strength of the old.

My question is this: what kind of loading scenarios should we be looking at? And by this I mostly mean what magnitudes and distributions should be considered.

Any thoughts on this topic would be helpful.

[Dash]

There are some basic scenarios that most people use. Using the search feature probably would have found them a lot faster than me answering your question though.

3g bump
2g turn
2g stop

Although, depending on what team you are those might need to change ( you guys picking up wheels in those photos ).

[exFSAE]

I would consider aiming for a stiffness and strength spec that meets your requirements, rather than matching a previous product.

[Adambomb]

exFSAE is right, ultimately it is up to YOU to determine what you want or think is adequate, although IMO it would be interesting to benchmark against some commonly available wheels. Before investing a considerable amount of time into fabbing wheels I would be curious to see the gains vs. whatever you can get off the shelf for undoubtedly less time and perhaps less money than building your own.

As for loading that's easy, as a wise man once said, "FBD that $hit."

[swong46]

Its going to take a lot of work/time to design a wheel center that has a better strength to cost ratio. I don't know how many man hours or money you have, but I know we sure don't hah.

They sell so many configurations 3/4 bolt, 3/4/6/8 spoke, etc

[Maxlaval]

Just thought i'd share on the matter.
I Have gone down that path and i can clearly tell you that there arent any real gain to make unless maybe going to composite. The gain are really minimal and most likely you will need a lot of money and time to build your first set of wheel.( I am not telling you not to do it, you will gain a lot of knowledge from this experience). First of all just start by reading on how to apply the loads from your tire to the outer-shell and you will see that the tire is quite hard to understand... It's easy to make a wheel with a terrible weight. But making a wheel that is optimize and won't fail on you during the endurance is another thing.

The loading scenario was found fron our data acquisition and then we added a Safety factor. We had to make sure that the rim would survive an impact but not tons of them.

The loading will vary according your tire, aero and weight.

Now for the scenario.
Try full braking with a bump.
Full lateral with a bump
Part braking, part turning with a bump.

To figure out these load you need data. If not most likely your system will be overkill or will fail.

You could always look at the TTC tire data but then again those value are quite high compare to reality.

[Buckingham]

I would suggest having a fatigue target in mind. Remember that the wheel sees fully cycled loading every revolution. How many miles of "normal operating condition" cornering do you want your wheels to last?

It is a good idea to baseline against your current wheel, but does your current wheel meet or over/under exceed your target design life?

I've purchased wheels that have only lasted two years (testing and competition) before fatigue cracks showed up at every spoke on all four wheels.

For some teams two years would be an acceptable design life, for other it wouldn't.