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#3312352 - 03/14/14 11:23 PM Crankshaft Design
MolaKule Offline


Registered: 06/05/02
Posts: 17465
Loc: Iowegia - USA
_________________________
I dropped a helium balloon and a brick and they did not hit the ground at the same time. So much for that theory. smile


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#3312367 - 03/14/14 11:59 PM Re: Crankshaft Design [Re: MolaKule]
Shannow Offline


Registered: 12/12/02
Posts: 33924
Loc: Oz
That's a lot of information in a small space, thanks.

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#3312379 - 03/15/14 12:22 AM Re: Crankshaft Design [Re: MolaKule]
expat Offline


Registered: 05/12/09
Posts: 5117
Loc: Canada
Thanks for posting.

But to put things in perspective:

Austin Seven two bearing crankshaft:

http://www.a7c.co.uk/parts/BB1photo.jpg

Amazingly they will run 6k rpm

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#3312388 - 03/15/14 12:37 AM Re: Crankshaft Design [Re: MolaKule]
edhackett Offline


Registered: 06/09/03
Posts: 1784
Loc: Sequim, WA
Here's Alfa Romeo's take on a 4 cylinder crank from the mid 50's through the end of production of the Alfa designed engines.



Ed
_________________________
Never attribute to engineers that into which politicians, lawyers, accountants, and marketeers have poked their fingers.

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#3312418 - 03/15/14 01:46 AM Re: Crankshaft Design [Re: MolaKule]
Shannow Offline


Registered: 12/12/02
Posts: 33924
Loc: Oz
Quote:
There were some initial problems with bolt-on counterweights, which resulted (as one Formula One designer told me) in "several deep holes being dug in the surface of a few racetracks". There are tensile and fatigue stress issues, as well as the inevitable fretting between contact surfaces and the requirement for highly developed fastener technology.


Having observed more than a couple of high cycle fatigue failures of turbine blades, with horizontal shaft rotating equipment, there is obviously a 2g difference in the centripetal acceleration at 12:00 versus 6:00.

Most of the genuine high cycle fatigue (calc'd at 170x10^6 cycles from crack to failure in most) ones that I've seen have ultimately failed at around 6:00, as evidenced by trajectories and consequential damage.

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