Ti strength depends greatly on alloy just like steel. In general for the same diameter steel will be stronger. The thread on an axle causes a high stress concentration and strength alone is not the only spec that determines durability, Toughness and notch sensitivity are the important factors. Titanium is usually used in greater volume to make up for lower strength and stiffness the fact that it has only 55% of steels density makes it superior to steel in some applications. It is a poor subsitute for steel in the rear axle application where the steel design is marginal anyway as it is in any 5/6/7 speed design with a substantial axle overhang. The Shimano cassette design was in part a way to regain axle strength by moving the support bearings out board to reduce the bending stress on the rear axle. As far as Titanium in 747's it is mainly used in the fasteners(HILOKS) and this was one of the first widespread commercial use of TI. Otherwise very little of the structure is Ti. I could not imagine a Ti submarine hull, that would be $$$$$$$$$$
From: Bikerdaver@aol.com Date: Wed, 21 Mar 2001 00:04:40 EST Subject: Re: [CR]Re: Campy Ti axles --- don't call it Titanium for nothing To: sachs@erols.com, chuckschmidt@earthlink.net, monkey37@bluemarble.net Cc: classicrendezvous@bikelist.org
In a message dated 3/19/01 7:39:19 PM PST, sachs@erols.com writes:
>Just a note of caution re this particular excursion with "unobtanium:"
> At an equivalent diameter, Ti will not be as resistant to bending as
>steel
> (as I recall it).
>
They don't call it Titanium for nothing. Ti at ANY diameter will be stronger
than steel. The fact that they make submarine hulls out of the stuff is a
dead give away. Or better yet, the wing skeleton of a 747 is made from Ti
tubing. You can pick up a 50 ft section with a 8 inch diameter and wall
thickness 1.5mm, drop it from over your head: It won't even ding. Try do
that
with any steel alloy of the same configurations any day of the week. Cheers,
Dave Anderson