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Fatigue Life of Aluminum



 
 
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  #31  
Old July 25th 17, 10:36 PM posted to rec.bicycles.tech
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Default Fatigue Life of Aluminum

On Tuesday, July 25, 2017 at 7:57:18 AM UTC-7, Joerg wrote:
On 2017-07-25 07:31, wrote:
On Tuesday, July 25, 2017 at 7:20:30 AM UTC-7, Joerg wrote:
On 2017-07-24 18:18,
wrote:
On Monday, July 24, 2017 at 12:00:37 PM UTC-7, Joerg wrote:
On 2017-07-24 06:18, David Scheidt wrote:
John B. Slocomb wrote: :On Sun, 23 Jul
2017 18:45:08 -0700 (PDT), jbeattie
wrote:

:The fatigue life of aluminum is

:In 1965 or 6 I worked on DC-3's built in the 1930's. My
mother had

Some of those DC-3s are still working. There's someone who
put turbo props on them, even. They're not pressurized, so
they dont' suffer from pressure cycles, and they structure is
such that every part can be replaced, without too much other
changes.


The Goon still flies passengers:

https://www.youtube.com/watch?v=OJBpwXSz_io

You can absolutely guarantee that every piece of aluminum on that
aircraft has been replaced.


I doubt it. I have also seen some south of here that looked really
old and flew regular routes. On this one they didn't even invest
much in modern avionics:

https://www.youtube.com/watch?v=3QSv3Gs4FHU


In the hanger I've watched them replacing sections of aluminum
paneling on the wings because of cracking around the rivets. They
didn't treat it as anything unusual and were quite professional in
drilling out the old rivets, walking off with the panel and then
showing up again later with a new panel and riveting it back in
place.


Sure, wing paneling in high stress area will have to be replaced once in
a while just like we need new rims on our bicycles at times. But not
every piece of aluminum on the aircraft. Look at the cockpit in the
video where it seems nothing of the aluminum there ever got replaced.
They probably have to don rain coats when the weather is bad.


DC-3's and 4's were real work horses. You didn't see anyone using the
larger prop planes.


Up north they still fly the others commercially, too:

https://www.youtube.com/watch?v=3RUIjlfdy4s
https://www.youtube.com/watch?v=yE2eQJGBcjU
https://www.youtube.com/watch?v=kvWpAVYdEeI

Getting back to bicycles I am amazed what the aluminum on my MTB takes.
It is my first aluminum bike and I was initially skeptical. This bike
often has to go through nasty turf while loaded to the gills (it's
modded in back for that). Then there are the rock hits at higher speeds.
When they hit my shins it hurts a lot and often blood flows. When they
hit the down tube there is a loud *KANG* and sometimes I think "Well,
that one must have made a dent". And when I stop and look it didn't,
just scratches.


Remember that because of the fatigue characteristics of AL they usually overbuild them. They can do this without adding much weight so it's the smart thing to do.
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  #32  
Old July 25th 17, 11:21 PM posted to rec.bicycles.tech
Nick[_4_]
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Default Fatigue Life of Aluminum

On 24/07/2017 02:52, jbeattie wrote:
On Sunday, July 23, 2017 at 6:45:12 PM UTC-7, jbeattie wrote:
The fatigue life of aluminum is


Damn, posted prematurely. But the answer is 12 years.


My previous one, a Trek, only lasted about five years before the right
chainstay snapped going over a pothole in the City. As total bike
failures go it was quite anticlimactic, just a severely rubbing back wheel.

  #33  
Old July 25th 17, 11:43 PM posted to rec.bicycles.tech
JBeattie
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Default Fatigue Life of Aluminum

On Tuesday, July 25, 2017 at 3:22:16 PM UTC-7, Nick wrote:
On 24/07/2017 02:52, jbeattie wrote:
On Sunday, July 23, 2017 at 6:45:12 PM UTC-7, jbeattie wrote:
The fatigue life of aluminum is


Damn, posted prematurely. But the answer is 12 years.


My previous one, a Trek, only lasted about five years before the right
chainstay snapped going over a pothole in the City. As total bike
failures go it was quite anticlimactic, just a severely rubbing back wheel.


Mine just made clicking noises which basically blended in with all the other creaks, groans and clicking noises. If the chainstay failed, the seatstays would have held, and like your bike, the upshot probably would have been more noise and some braking. No epic disaster.

Cannondale is pretty good with warranty replacement. We'll see how generous they are this time. My last replacement attempt was a pre-CAAD straight gauge 6061 frame that died after 20+ years. I took it in for warranty replacement, and the local rep. told me I just wore it out. I had two early CAADs that cracked at the 5 year mark or thereabouts. They had those ridiculous cantilever stays/dropouts that were prone to failure, and they were replaced. The last replacement was a CAAD 9.That is a great bike -- now residing with my son Utah.

-- Jay Beattie.





-- Jay Beattie.
  #34  
Old July 26th 17, 04:01 PM posted to rec.bicycles.tech
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Default Fatigue Life of Aluminum

On Tuesday, July 25, 2017 at 3:22:16 PM UTC-7, Nick wrote:
On 24/07/2017 02:52, jbeattie wrote:
On Sunday, July 23, 2017 at 6:45:12 PM UTC-7, jbeattie wrote:
The fatigue life of aluminum is


Damn, posted prematurely. But the answer is 12 years.


My previous one, a Trek, only lasted about five years before the right
chainstay snapped going over a pothole in the City. As total bike
failures go it was quite anticlimactic, just a severely rubbing back wheel.


This is the beauty of metal over carbon fiber. Metal generally fails at the weakest points which are things like the bottom of the fork legs and the the stays. Steel doesn't suffer fatigue limits for anything under 75% of maximum strength though AL has a linear fatigue line.

Carbon fiber is much stronger than AL per lb. but they are building them lighter and lighter and they too have the same linear fatigue line and can fail much sooner since their maximum strength is less with reduced material. Plus you cannot tell manufacturing errors as easily though I understand that a lot of the inspections now use 100% ultrasound inspection. That still relies upon the inspector paying 100% attention to his work.

I do believe that they can build a fairly light CF frame and fork that has an almost unlimited lifetime but I also know that they do not.
  #35  
Old July 27th 17, 03:07 AM posted to rec.bicycles.tech
SMS
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Default Fatigue Life of Aluminum

On 7/23/2017 6:52 PM, jbeattie wrote:
On Sunday, July 23, 2017 at 6:45:12 PM UTC-7, jbeattie wrote:
The fatigue life of aluminum is


Damn, posted prematurely. But the answer is 12 years. My Cannondale CX qua commuter bike bit the dust. I was doing my occasional maintenance -- which was extensive because the BB, RD and FD had gone to sh**. The pulleys had shark's teeth, and the FD cage had practically worn through. The BB was shot, and the bike was creaking like crazy, including a snapping sound that made be a bit nervous -- and for good reason. The left side chain stay had practically cracked all the way around. Waaah. Bike two down (Supersix in roof rack incident). I'm down to one bike -- the Roobay. Time to go on a buying spree for a fast commuter.

-- Jay Beattie.


12 years is pretty good for a heavily used aluminum bicycle. They last a
lot longer when they are rarely used! The chainstay cracking is the
usual failure, the main tubes don't often crack.
  #36  
Old July 27th 17, 11:34 AM posted to rec.bicycles.tech
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Default Fatigue Life of Aluminum

commuter ? Sports bike ?

We lost our energy expert. I doahn have time fir that.

What's the 12 year energy expenditure fir steel vs AL ? Is there an immediate negative post commute physical effect for steel vs AL riding by a lawyer ? Prob not. The AL feels faster.

I'm steel over 10 years. The bike will be here when the sun sets.

12 years on a bone rattling beer can is impressive. Junk. The thought of it is repellant.

What now ?

  #37  
Old July 27th 17, 02:35 PM posted to rec.bicycles.tech
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Default Fatigue Life of Aluminum

On Wednesday, July 26, 2017 at 7:07:15 PM UTC-7, sms wrote:

12 years is pretty good for a heavily used aluminum bicycle. They last a
lot longer when they are rarely used! The chainstay cracking is the
usual failure, the main tubes don't often crack.


I had every model in the Colnago Dream series and they all had been heavily used when I got them. They were in perfect mechanical shape. And I put thousands of miles on them myself. So as I said before - most AL bikes are overbuilt since the metal is so light that there is little penalty for doing so.

  #38  
Old July 27th 17, 04:01 PM posted to rec.bicycles.tech
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Default Fatigue Life of Aluminum

On Thursday, July 27, 2017 at 9:35:34 AM UTC-4, wrote:
On Wednesday, July 26, 2017 at 7:07:15 PM UTC-7, sms wrote:

12 years is pretty good for a heavily used aluminum bicycle. They last a
lot longer when they are rarely used! The chainstay cracking is the
usual failure, the main tubes don't often crack.


I had every model in the Colnago Dream series and they all had been heavily used when I got them. They were in perfect mechanical shape. And I put thousands of miles on them myself. So as I said before - most AL bikes are overbuilt since the metal is so light that there is little penalty for doing so.


all the Cols C buys are in perfect mechanical shape
  #39  
Old July 27th 17, 05:50 PM posted to rec.bicycles.tech
Doug Landau
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Default Fatigue Life of Aluminum

On Monday, July 24, 2017 at 8:12:51 PM UTC-7, John B. Slocomb wrote:
On Mon, 24 Jul 2017 09:25:38 -0700 (PDT), Doug Landau
On Monday, July 24, 2017 at 6:09:28 AM UTC-7, AMuzi wrote:
On 7/24/2017 4:49 AM, wrote:
Al cookware is highly suspect for causing Alzheimers


Like the 'phillpis curve' and other fantasies of the 1970s,
that was roundly debunked years ago.


what are some others?


Try googling it.


What about the guy who live in the main woods for 30 yrs w/o seeing anyone?
 




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