NoahKatz wrote:
If there's enough margin on steel wishbones, why couldn't you use 6061-T6 at the same dia./wall thickness?
I did say "pedantic" engineering!
But your'e right, in many cases of road cars, steel is generally used at 1.3 to 1.5 safety margin so at a 1.0 safety margin your aluminium could directly replace the steel. However at a 0.8 - 0.9 safety margin with steel that a top line race car engineer may take a chance with, then the aluminium at 1.0 can not compete - go look at what top race cars still use and used before CF suspension parts came along, ie; steel alloys.
NoahKatz wrote:
Seems to me they'd have ample fatigue life if they're designed to handle the large load cases like hitting a curb, which would be a very infrequent occurrence in the scheme of things.
I totally agree, the "aluminum fatigue" line is done to death by the 'Flat Earth Society'. Millions of MX bikes give their aluminium swingarns absolute hell and extreme stresses every weekend for many years, well proven but they have to be bigger in section than steel alloys and larger use of gusseting at joints and rod ends thus not suitable for most race cars.
By the way, Triumph (old) and BSA motorcycles both who use aluminum con rods since the 50's and there's not much in the automotive world that gets stressed in every direction and in every way possible more than a con rod. Their pushrods are aluminum also, big stresses there too.