[atomicfire]

I was researching and trying to put an end to the question - will the powdercoating procces damage or reduce the load capacity of the forged wheels?

I have access to FEA software and i'm going to attempt to create a model, and try it out to see exactly what happens. It just happens that this is almost exactly the thing i'm studying for a degree.

So, to do this I need to know what type of metal the wheels are made of. I need to know the specific alloy\content or alloy type, where then I can put in the values for its variables into the FEA software.

--AtomicFire

[bdi]

Not a bad idea man. I use FEA extensively myself. What software do you use? I use COSMOS from solidworks.
I say just use a standard type of Al Alloy to do your study. Im pretty sure no one knows for sure what the exact alloy contact is of the stock BBS wheels unless some one works in a Materials Lab.
I think the hardest part is going to be finding out how deep the powder coating process penetrates the material of if it does at all. Also trying to find out the heat treatment specs.

Have fun.

[wundej]

FEA is much more than just meshing a model and throwing a few boundary conditions onto the FEM and solving it.

Things you need to even remotely come close to obtaining accurate results:

1. The exact alloy of the wheel
2. The mechanical history of the wheel. This means any type of changes that the wheel went through while being made. We know that they are forged, but are they subjected to any sort of heat treatment or powder coating.
3. A mathematical way to represent a forged wheel as apposed to a generic sample of the alloy that you would get your material values from. Obviously the forged wheel is going to behave differently than a cast wheel, you need to take this into account in the analysis.
4. finally before you define your material properties for your elements you would need to know what your powder coating curing temps and durations.

So once you figure out the material properties of the finished forged wheel, and know if it has undergone any type of heat treatment in the past you can model the wheel and mesh it.

The next step would be to use a thermal analysis to fully understand the temperatures through the wheel as it is being cured during powder coating (what bdi said). You will need a software that has a thermal solver (I've used I-DEAS for this sort of analysis, which uses MAYA's TMG Thermal solver), most higher end FEA packages have this capability, your main issue will be making sure you have a license. This analysis will need to take into account the total time that the wheel will be cured and you also need to understand that not all PC ovens are controlled perfectly, their temps can vary a lot. Once you get your results you should be able to cross section the model and see the resulting temps of the wheel and spokes. It would be beneficial to be able to view this over a period of time, not only as a final condition. You can then determine the heat treat spec that is similar to the temps/duration the wheel was cured at.

The main issue w/ powder coating wheels is that some wheels have already been heat treated and the curing process for PC can overage the alloys which will end up making them weaker than they were before PC.

Then you can perform an impact analysis and static load analysis. Do some calcs by hand to figure out forces (make some assumptions here, like you are running over a curb that is 4" high at x mph, you can then calculate the resultant force of the curb on the wheel). Take the results of these and then compare them with results of a pre-powder coated wheel.

In most cases any powder coating process at a higher temp will cause a loss of some structural integrity of a wheel. It's not a very easy task to verify this unless you have access to all of the design data, which we don't.

The other main thing to remember is that this case is not something that you can run through a "Wizard" style analysis package. Something like cosmos works express (built into SW) won't cut it here, full blown cosmos can do all of this, I-deas can do all of this, NX Nastran / msc.nastran, etc can do this.

FEA is one of those things where the phrase "Garbage in = Garbage out, where Garbage Out =GarbageIn^2" really applies. If your mesh isn't very good, your results will be inacurrate, if you boundary conditions are off, your results will be off. There are a lot of factors in this problem so it's a tough one to get accurate results.

It might be better if you start off by trying a simple model where you know the alloy, run a base fea on that. Then change your material to the heat treated specs, then run a FEA on that. It will give you an idea of what your results might be.

This would have been a great senior design project for someone. I did a lot of FEA work for my senior design on the chassis of a FSAE car.

Sorry for the long post...just wanted to make sure you had all the info you'd need to get through this if you end up doing it. I'd love to see what you come up with (and if you spend the time modeling the wheels, post that up). Hopefull this might be useful to someone when they ask "is it OK to Powder coat my wheels?" It's much harder to answer than anyone might think.