New Idea!

[02stu]

I'm pretty sure that decreaseing the wall thinkness will only significatly lower the chance of fracture in polymers. As far as extruding the mount for strength goes, I can't remember for sure but I don't think aluminum responds all that well to work hardening. Sounds like Brandon would definitly know. Can someone send me how long this thing needs to be, and any other dimensions you have? Thanks
-Stu

[BimmerToad]

This might be a bit dry (got my Deformation and Fracture Mechanics book out):

"when a sample is thin, and the degrees of plastic constraint acting at the crack-tip minimal, plane-stress conditions prevail and the material exhibits maximum toughness"

likewise,

"Alternatively, when the thickness is increased to bring about plastic constaint and plane-strain conditions at the crack tip, the toughness drops sharply to a level that maybe one-third (or less) that of the plane-stress value."

Look at most aluminum parts, they are relatively thin, so that the material fractures in plane-stress conditions, which allow for easily detected cracks, and a greater toughness. This part should be designed tougher than stronger. The brace doesn't support all that much. I don't think the brace needs to be made of solid billet.

The strain-hardening coefficient of aluminum is 1/3rd of stainless steel, so it will respond to work hardening, but not as well as steel. Work hardening makes the material stronger, but also more brittle, so I think it would be a waste of time.

Put the design up in Solidworks and run some FEA analysis. I'm sure what is designed will be overbuilt regardless

Never thought I'd post information from my materials class on r3v ;)

[X2theZ3]

What do you guys mean by filleting the edges or corners? Would this be adding "ribs" to the inside corners?

No,

filleting is just solidworks stuff. Just means rounding the edges or corners. Here, the purpose is less stress at the corners.

[Beej '86 325es]

I think basically what you guys are saying is that with thicker material the tensile and yield points are closer together. Simply put a sheet of aluminum is more likely to bend, where a block is going to break. I don't have any FEA analysis software unfortunately. I'm not a stress engineer (I didn't want to do homework for the rest of my life), so I went into design.

This bracket will be overkill, but 7075-T6511 would put a nice warm fuzzy feeling in my stomach. The bracket shouldn't need to be extruded more than about 2". I would like to see what we can do about the zig-zagyness of the bracket though.

[joshh]

No,

filleting is just solidworks stuff. Just means rounding the edges or corners. Here, the purpose is less stress at the corners.

Ah, thanks. The correct deffinition was not in the dictionary so I knew it was a bit over my head.

So the idea is the bracket to be somewhat "hollow"? More like very thick sheet metal? But obviously not.

[02stu]

[QUOTE Simply put a sheet of aluminum is more likely to bend, where a block is going to break.[/QUOTE]

Well said, its kinda odd all this just came up. I have a material science final exam in 4 days!

[X2theZ3]

Well said, its kinda odd all this just came up. I have a material science final exam in 4 days!

yeah, weird. mine's in a week and a half.

[erik325i]

Any update on the brackets? I would like one.

-Erik

[CarsSuck]

Did anything ever come of this?

[PiercedE30]

You guys went through all this research and planning just to drop it or are you all secretly consorting against us with your brackets?

[02stu]

I don't know what happened to it, I dropped it because I found out my 240 tranny didn't need one. I think people are just going with the e36 transmission. There is definitly money to be made if someone can produce them.

[bmws50b30]

i'm using my getrag 260 until the center bearing wears off then i'm switching to the ZF trans.

i got a 98 zf trans with 40K miles for 500 shipped and a 3.25 lsd for 175 shipped. i just need to get a remanufactured e30M driveshaft.

[Drew325is]

Count me in on this!...but will it be okay to ship to Australia (I'll pay the extra shipping cost of course).

[rede30]

I wish this brace was made.

[Drew325is]

Digging up an old thread here...but did this ever get anywhere?