thermal fatigue influences on the brake disc

[Vinnie]

does anyone have the material properties as a function of temperature for al-2024, al-7075 and st50 steel? And does anyone know the thermal fatigue influences on the above mentioned materials?

I need to do a FEA on our brake discs because they will be custom made. How do other teams, who make their own brake disc, implement the thermal fatigue on the brake disc??

[Vinnie]

does anyone have the material properties as a function of temperature for al-2024, al-7075 and st50 steel? And does anyone know the thermal fatigue influences on the above mentioned materials?

I need to do a FEA on our brake discs because they will be custom made. How do other teams, who make their own brake disc, implement the thermal fatigue on the brake disc??

[Jersey Tom]

We don't. We use plain ol waterjetted HRS discs. If there was ever heat cracking or excessive wear, we'd just replace em. But I've never seen either happen.

Remember, this is a FSAE car. The amount of service hours going into these things is very small. After a track day, inspect the rotors. If they're done, they're done.

I'd be much more concerned about a straight aluminum rotor smearing or shredding without some pretty special pads.

[NetKev92]

You can scour the internet for Mil handbook 5 or MMPDS, the military and FAA approved material data for typical metals. They have a lot of data on aluminum including fatigue properties and some temp behavior. If you can't find it there, the data will probaby cost you $.

Mil handbook 5 was a military document on metal properties. Given the significant commercial use of metals though in other products, the document was handed over to civil authorities to maintain and became the MMPDS. There are free copies on the internet but it may take some digging. Now everyone's trying to sell a printed-off copy, so the free download is buried somewhere on the net. It was easy to find two years ago, kinda painful now.

[Jersey Tom]

You can get a trial student account with the ASTM materials library as well, which has TONS!!! of data sheets on mechanical properties, fatigue, heat treating, etc of basically any metal you can think of.

I was downloading like a savage animal when I had my trial.

[Vinnie]

we have the mil handbook, but if I use that it would result in a max stress of less than 20% of the max yield strenght of the material, this is kinda low and the brake disc would become very chubby if I apply it.

I have followed your advice Tom and became a student member, hope this will clear things out, but any other suggestions are always welcome..

cheers and happy new year to you all

vinnie

[raska]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">I'd be much more concerned about a straight aluminum rotor smearing or shredding without some pretty special pads. </div></BLOCKQUOTE>

Wilwood sells them.

[Samo Simonian]

Hey Guys,

Careful using MIL Handbook, it's often high class stuff they use there (you can find reduction factors).
Also, the standard Sigma N curves for fatigue tell you, that at that stress, for that number of cycles
there would not have been any crack inititiation! Which means that the material could last way longer.
Overall it is quite complex, and fundamentally necessary to do a good approach towards these calculations.
We also had a struggle.
If you don't want to break your head (maybe literally) on optimizing, don't, be safe.

I plan on writing a little document on this, don't know about time resources though.

Greetz,

Samo Simonian
Chief Suspension
DUT Racing 2006/2007
www.dutracing.nl (http://www.dutracing.nl)