Hi there, you seem to know enough about the subject already, but i did a similar project and used the cambridge material selector (CMS) which sounds similar to the program you have. I assume they would have taught you how to derive certain material property parameters (not sure this is the correct term) that are not always obvious, but generally involve the superposition of linear selection lines of varying slope on 2D graphs of material properties such as those you have mentioned. I am surprised cost is not an important factor, because if its not you would just go ahead and use a nickel based alloy or titanium - hell why not CFRP or intermetallic? You could produce the only single crystal nickel superalloy brackets ever made, but why bother when there isn't really a difference between this and a decent Al alloy below temperatures of 500 degrees C!

In reality, you would choose a cheaper metal with good fatigue and toughness characteristics at room temperature - hence the aluminium alloy or plain carbon steel. Workability is also very important. The endurance limit applies to some metals (either ferrous or non-ferrous cant remember now!) that will not fail under even an infinite number of load cycles at a stress up to what is then referred to as the endurance limit.
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'87 MC16