Fatigue Life of Aluminum

[jbeattie]

The fatigue life of aluminum is

[jbeattie]

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.

[avag...@gmail.com]

SUE

claim emotional distress

Loss of a beloved artform

Endangerment

[avag...@gmail.com]

BTW. the A post is trashable

Gotta OD number ? time on roaD ?

now the ride is plastic

Howbouthat !

I npw have a plastic (vinyl) BD batt power circular saw werks AAA

Cuts tuba...amazing

[John B. Slocomb]

On Sun, 23 Jul 2017 18:45:08 -0700 (PDT), jbeattie
<jbeat...@msn.com> 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
aluminum cooking pots that she bought in ~1930 and lasted until her
death in 1992.
--
Cheers,

John B.

[avag...@gmail.com]

Al cookware is highly suspect for causing Alzheimers

[AMuzi]

On 7/24/2017 4:49 AM, avag...@gmail.com 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.

--
Andrew Muzi
<www.yellowjersey.org/>
Open every day since 1 April, 1971

[David Scheidt]

John B. Slocomb <sloc...@gmail.com> wrote:
:On Sun, 23 Jul 2017 18:45:08 -0700 (PDT), jbeattie

:<jbeat...@msn.com> 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.


--
sig 22

[cycl...@gmail.com]

On Monday, July 24, 2017 at 2:49:44 AM UTC-7, avag...@gmail.com wrote:
> Al cookware is highly suspect for causing Alzheimers

Yeah and the fact that Froome is a good rider proves that he is doping.

[Frank Krygowski]

On 7/23/2017 9:52 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.

Back in 1978 or so, I designed and made my own handlebar bag. The bags
I had at the time had a 1/4" steel hanger frame that looped under the
stem and over the handlebar.

I decided to try an aluminum hanger frame on mine. I used a 3/8" rod of
2024, annealed it, bent it into the pretty contorted shape, then heat
treated it again. I'm sure it saved me as much as an ounce.

I wondered how soon the aluminum would fatigue. But it's been fine for
40 years now.

> Time to go on a buying spree for a fast commuter.

Isn't that an oxymoron?


--
- Frank Krygowski

[Doug Landau]

On Monday, July 24, 2017 at 6:09:28 AM UTC-7, AMuzi wrote:
> On 7/24/2017 4:49 AM, avag...@gmail.com 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?

[jbeattie]

[jbeattie]

I'm having a real problem with messages being sent involuntarily! I like quick commuters that I can take home through the hills without feeling like I'm dragging a boat anchor. I don't use panniers.

The Cannondale CX was pretty robust, but after 12 years of daily commuting with a lot of out of the saddle climbing and general thrashing, the chain stay gave up. I'll see what the warranty guys will do for me today. The problem with getting a replacement Cannondale is that none of their bikes have threaded BBs, which are making a comeback with some other manufacturers. I'd probably be fine with a BB30 or PF30, but I like the idea of cheap and easy BBs.

-- Jay Beattie.

[avag...@gmail.com]

I doahn know what IT proves but serial wins needs descriptive analysis for our entertainment ...anyone know of cycle journalism in this area ?

[avag...@gmail.com]

Al leaches

http://scholar.google.com/scholar?hl=en&q=alzheimers+aluminum+cookware&btnG=&as_sdt=1%2C10&as_sdtp=

need BPA bottles ?

or Teflon particles lodged in your intestines ?

drink heavy cream with morning coffee ?

[Joerg]

The man-made ice age, for example. I still remember that us kids got
quite scared about that. No it's become man-made global warming. Oh
wait, no, the last iteration is global change. Wot nonsense.

--
Regards, Joerg

http://www.analogconsultants.com/

[Joerg]

The Goon still flies passengers:

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

[avag...@gmail.com]

another cycle journalism op

12 years in Al....outstanding performance.

12 years ago what were your final choices ?

and today what models do you start with ?

as a Portlander there's a considerable head start on ground knowledge we other landers doahn have.

are you headed for a full custom or another off the rack robust road runner ?

at this pt, I'd be measured fersure

[cycl...@gmail.com]

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

[Doug Landau]

> >The fatigue life of aluminum is
>
> In 1965 or 6 I worked on DC-3's built in the 1930's. My mother had
> aluminum cooking pots that she bought in ~1930 and lasted until her
> death in 1992.

Is this scene accurate?
https://www.youtube.com/watch?v=SQRGuX_a5Fg

[John B. Slocomb]

Try googling it. I get 40,400 replies in mere seconds.
--
Cheers,

John B.

[John B. Slocomb]

On Mon, 24 Jul 2017 11:52:43 -0700, Joerg <ne...@analogconsultants.com>
wrote:

I don't think there is any doubt that the earth is getting warmer. The
arguments seem to be whether it is a normal temperature swing and
what, if anything, is causing it.
--
Cheers,

John B.

[John B. Slocomb]

Yes, there are a surprising number in "daily" use and yes they are
pretty easy to fix. But then so are most aluminum airplanes.

--
Cheers,

John B.

[John B. Slocomb]

No it isn't. although the results are pretty much what will happen if
a "gun ship" were to fire on a crowd.

The mini guns on a C-47 gun ship, which the video does picture, were
initially fixed a fairly shallow angle and in about 1966, or so the
angle was increased so they the aircraft didn't need to bank so
steeply, but in any case the aircraft would be banked and circling the
target when they fired.

In an actual attack all three of the guns would probably have been
fired. Accuracy was sufficient that when we tested the new higher
angled mounting we dropped an empty 5 gal drum in the bay, from about
500 ft, and circled around and made a 1 second firing pass. There was
a sort of explosion of spray and when the spray settled there was
nothing there.

Seems to be a composite film made of actual gun ship flights
https://www.youtube.com/watch?v=uKOrpyO0z48
--
Cheers,

John B.

[John B. Slocomb]

On Tue, 25 Jul 2017 11:13:24 +0700, John B. Slocomb
<sloc...@gmail.com> wrote:

>On Mon, 24 Jul 2017 18:46:21 -0700 (PDT), Doug Landau
><doug....@gmail.com> 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
>>> aluminum cooking pots that she bought in ~1930 and lasted until her
>>> death in 1992.
>>
>>
>>Is this scene accurate?
>>https://www.youtube.com/watch?v=SQRGuX_a5Fg
>
>No it isn't. although the results are pretty much what will happen if
>a "gun ship" were to fire on a crowd.
>
>The mini guns on a C-47 gun ship, which the video does picture, were
>initially fixed a fairly shallow angle and in about 1966, or so the
>angle was increased so they the aircraft didn't need to bank so
>steeply, but in any case the aircraft would be banked and circling the
>target when they fired.
>
>In an actual attack all three of the guns would probably have been
>fired. Accuracy was sufficient that when we tested the new higher
>angled mounting we dropped an empty 5 gal drum in the bay, from about
>500 ft, and circled around and made a 1 second firing pass. There was
>a sort of explosion of spray and when the spray settled there was
>nothing there.

correction, that should have read 55 gallon barrel

[AMuzi]

'peak oil', laetrile

[Frank Krygowski]

On 7/25/2017 9:00 AM, AMuzi wrote:
> On 7/24/2017 10:12 PM, John B. Slocomb wrote:
>> On Mon, 24 Jul 2017 09:25:38 -0700 (PDT), Doug Landau
>> <doug....@gmail.com> wrote:
>>
>>> On Monday, July 24, 2017 at 6:09:28 AM UTC-7, AMuzi wrote:
>>>> On 7/24/2017 4:49 AM, avag...@gmail.com 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. I get 40,400 replies in mere seconds.
>> --
>> Cheers,
>>
>> John B.
>>
>
> 'peak oil', laetrile

Trickle down economics. "We will be greeted as liberators."

Oops. Not ancient enough, sorry.


--
- Frank Krygowski

[Joerg]

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

[cycl...@gmail.com]

As a matter of fact there is a LOT of questions about whether it is "getting warmer" and if so how long this cycle will last. Warm periods occur every millennia or so and generally last about a century or two.

Man has no effect on it. What's more - NASA and NOAA falsely generated a report for Obama to present to the IPCC proving man-made climate change when the majority of their scientists totally disagreed with it.

If you want to see just how far they went:

https://en.wikipedia.org/wiki/File:Global_Temperature_Anomaly.svg

That is the chart from NASA. If you look at the steepest part of the chart it is from 1979 to present.

But the satellite data has this to say:

http://www.drroyspencer.com/wp-content/uploads/UAH_LT_1979_thru_March_2017_v6.jpg

Dr. Spencer worked for NASA and had access to the real data. While that looks like there is a small increase across that 38 year period that is nothing more than the chaotic weather patterns.

In short - people who want power will do ANYTHING to get it.

[cycl...@gmail.com]

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.

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

[Joerg]

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.

[cycl...@gmail.com]

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.

[Nick]

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.

[jbeattie]

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.

[cycl...@gmail.com]

On Tuesday, July 25, 2017 at 3:22:16 PM UTC-7, Nick wrote:

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.

[sms]

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.

[avag...@gmail.com]

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 ?

[cycl...@gmail.com]

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.

[avag...@gmail.com]

all the Cols C buys are in perfect mechanical shape

[Doug Landau]

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, avag...@gmail.com 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?

[sms]

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.

Well if you bought it new, you have a lifetime frame warranty, though
due to the bankruptcy and acquisition not sure how that works, and
getting them to honor the warranty is also dependent on the shop where
you bought it backing you up.

You really need to move to titanium or steel if you're expecting
longevity. I have steel bicycles that are >35 years old.

[Axel Reichert]

sms <scharf...@geemail.com> writes:

> On 7/23/2017 6:52 PM, jbeattie wrote:

[...]

>> the answer is 12 years

[...]

> You really need to move to titanium or steel if you're expecting
> longevity.

Neither frames made from aluminium, nor titanium nor steel have
"infinite life" (engineering term, typically used for 10 million
cycles). For the latter two metals this might be contrary to folk
wisdom, but no frame is designed for infinite life. It would be way too
heavy to find any buyer, so the engineers strive for finite life.

That said, for quite some years even the theory of infinite life of
steel (for loads low enough) seems to crumble, since micro-damage takes
place that accumulates and finally leads to failure.

Of course, it all depends on the loads, not only the size, but also on
the sequence (high first then low or vice versa, e.g.) and the
directions. With multi-axial and transient stress states (no clean,
constant sine load) it becomes marvelously complicated.

Best regards

Axel

[Tom Kunich]

On Monday, July 24, 2017 at 10:18:56 AM UTC-7, jbeattie wrote:
> On Monday, July 24, 2017 at 10:01:22 AM UTC-7, jbeattie wrote:
> > On Monday, July 24, 2017 at 7:27:28 AM UTC-7, Frank Krygowski wrote:

> > > On 7/23/2017 9:52 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.
> > >

> > > Back in 1978 or so, I designed and made my own handlebar bag. The bags
> > > I had at the time had a 1/4" steel hanger frame that looped under the
> > > stem and over the handlebar.
> > >
> > > I decided to try an aluminum hanger frame on mine. I used a 3/8" rod of
> > > 2024, annealed it, bent it into the pretty contorted shape, then heat
> > > treated it again. I'm sure it saved me as much as an ounce.
> > >
> > > I wondered how soon the aluminum would fatigue. But it's been fine for
> > > 40 years now.
> > >

> > > > Time to go on a buying spree for a fast commuter.
> > >

> > > Isn't that an oxymoron?
> I'm having a real problem with messages being sent involuntarily! I like quick commuters that I can take home through the hills without feeling like I'm dragging a boat anchor. I don't use panniers.
>
> The Cannondale CX was pretty robust, but after 12 years of daily commuting with a lot of out of the saddle climbing and general thrashing, the chain stay gave up. I'll see what the warranty guys will do for me today. The problem with getting a replacement Cannondale is that none of their bikes have threaded BBs, which are making a comeback with some other manufacturers. I'd probably be fine with a BB30 or PF30, but I like the idea of cheap and easy BBs.

I've been having problems with preposting and had to delete blank postings. As far as the fatigue life of aluminum goes - it depends on the alloy, the treatment of it and the number of cycles up to the near limits. That makes it impossible to solve for a fatigue life.

I've spent the last three weeks riding my Eddy Merckx aluminum Elite. It is a very good bike and rides well and steers good. Today I decided to take out that Douglas Ti again and the comparison was pretty shocking. Despite how good the Eddy is, there is no comparison with the Ti bike. I'll be interested in getting the Airborne together since it seems more lightly constructed (but not much).

[Tom Kunich]

That looks like a surplus C47. Since they were built by the thousands there were all over the place after the war. Douglas carried on building them as the DC-3 I think (maybe DC-2) Then then walked up the DC ladder to the four engine DC-7 The DC-8 was a jet passenger liner that wasn't a bad commercial aircraft at all.

[Tom Kunich]

Axel, while I completely agree that there is no such thing as an infinite fatigue life, steel and titanium frames are so seldom stressed up to the 75% level that is necessary to generate sufficient fatigue to cause such wear, that they might as well be infinite fatigue life. There are PX-10's around today that have been ridden HARD since 1960 when they were first released.

[Roger Merriman]

I’m not convinced that the material matters (to a point) but how the frame
was made and for what purpose, my first “Gravel” bike was a fairly cheap CX
bike that was clearly never intended to be raced! It was noticeably more
jarring than the Gravel bike proper that I replaced it with, same tires etc
both Aluminium.

Higher end race bikes seem to have little compliance as far as I can tell,
as folks who buy such bikes are interesting in stiffness and well looking
pro!

Roger Merriman

[James]

On 25/6/21 5:42 am, Axel Reichert wrote:
> sms <scharf...@geemail.com> writes:
>
>> On 7/23/2017 6:52 PM, jbeattie wrote:
>
> [...]
>
>>> the answer is 12 years
>
> [...]
>
>> You really need to move to titanium or steel if you're expecting
>> longevity.
>
> Neither frames made from aluminium, nor titanium nor steel have
> "infinite life" (engineering term, typically used for 10 million
> cycles). For the latter two metals this might be contrary to folk
> wisdom, but no frame is designed for infinite life. It would be way too
> heavy to find any buyer, so the engineers strive for finite life.
>

10 million cycles, eh?

At 80 revs per minute (does one rev constitute a cycle, or each pedal
stroke which would be 160 pedals per minute?), it would take me 125,000
minutes of cycling to reach 10 million cycles. That's about 2083 hours
of riding, and as my average speed is around 30km/h, requires 62,500km
of riding.

My current steel frame road bike has carried me over 100,000km so far,
in about 10 years of riding. Columbus Spirit in double oversize tubes.

--
JS

[pH]

My Cannondale frame is from the mid 1980's....am I on borrowed time?
The forks are steel and I keep an ear out for any 'creaking' noises besides
my joints.

Maybe it's time for that dream Rivendell/Atlantis/Homer Herkson(?) frame,
eh?

pH in Aptos

[Tom Kunich]

Although Frank would have a better idea, my understanding of a "cycle" is to stress a frame to within 75% of it's maximum mechanical strength limits. This turns out to be extremely difficult to do and my experience is that the frames that failed were not from fatigue failures but from manufacturing defects.

[Tom Kunich]

Older Cannondales tended to be pretty strongly built but I NEVER liked the way they rode. This was underscored yesterday. Since I have been riding that Eddy Merckx Elite and had come to think of it as a good easy riding bike, when I took the Douglas Ti out it was so much better ride that I can hardly believe it.

[Axel Reichert]

Tom Kunich <cycl...@gmail.com> writes:

> steel and titanium frames are so seldom stressed up to the 75% level
> that is necessary to generate sufficient fatigue to cause such wear

Next week I will be teaching a seminar that touches briefly on fatigue
analysis, see

https://abaqus-docs.mit.edu/2017/English/FesafePdf/FesafeFatigueTheory.pdf

I am still far from expert level, but I am very sure fatigue cannot be
reduced a simple number such as you seem to suggest.

Axel

[Axel Reichert]

James <james.e...@gmail.com> writes:

> 10 million cycles, eh?
>
> At 80 revs per minute (does one rev constitute a cycle, or each pedal
> stroke which would be 160 pedals per minute?), it would take me
> 125,000 minutes of cycling to reach 10 million cycles. That's about
> 2083 hours of riding, and as my average speed is around 30km/h,
> requires 62,500km of riding.
>
> My current steel frame road bike has carried me over 100,000km so far,
> in about 10 years of riding. Columbus Spirit in double oversize
> tubes.

Which means that your more than 10 million cycles did not result in
enough accumulated damage to cause failure of your frame. The loads were
most likely small.

See

https://en.wikipedia.org/wiki/Fatigue_(material)
https://en.wikipedia.org/wiki/Fatigue_limit

for a nice introduction and

https://en.wikipedia.org/wiki/Critical_plane_analysis
https://en.wikipedia.org/wiki/Rainflow-counting_algorithm

for some more details on how to deal with multi-axial stress states and
complex loading cycles.

Axel

[Tom Kunich]

Perhaps a question might be - do we agree that a load can be too small to EVER cause fatigue failure? And if that is the case, can that same small load lead to fatigue failure if some number of large loads occur?

These things have been carefully studied in supersonic aircraft and jet engines and they have carefully calculated the times to expected failures and replace effected items long before that. The loadings on ultrasonic aircraft are such that unless fatigue failures are accounted for they simply could not even exist.

Consider the loads on a SpaceX rocket that carries astronauts to the Space Station. Do you suppose that they only use that rocket once for fear of a fatal accident?

[Axel Reichert]

Tom Kunich <cycl...@gmail.com> writes:

> do we agree that a load can be too small to EVER cause fatigue
> failure?

That would imply that there is some infinite life (which is what many
cyclists believe for steel and titanium, but not for aluminium). A
colleague (material expert) said to me that this has been debunked in
recent years by researchers. Thus the answer to your question should be
"no" in my opinion.

> can that same small load lead to fatigue failure if some number of
> large loads occur?

That is almost certainly the case. Which is why aircraft manufacturers
analyze "barely visible damage", why car manufacturers analyze misuse
cases such as curb strikes or pothole events etc. The loading history is
crucial:

In our seminar we have a nice example of an automotive part that fails
in location A when exposed to a cyclic load x. It also fails in location
A when exposed to a cyclic load y (with a different mean stress and
amplitude). However, when exposed to load y ONCE and after that the
cyclic load x, it fails in location B. Surprising? Yes, but verified by
experiment and predicted by proper fatigue simulation.

> The loadings on ultrasonic aircraft are such that unless fatigue
> failures are accounted for they simply could not even exist.

Yes, I know the saying: Without crack, it won't fly.

However, from a structural analysis point of view, aircraft are not that
exiting because things are usually linear (small deformations, little or
no plasticity etc.), which makes things much easier to predict.

Best regards

Axel

[John B.]

On Thu, 24 Jun 2021 11:16:20 -0700, sms <scharf...@geemail.com>
wrote:

On the other hand, I worked on a DC-3, in Vietnam that was made in
1936 so about 32 years old at the time and I believe that they are
still in use... some 80+ years after first being introduced.

All aluminum too :-)
--
Cheers,

John B.

[John B.]

Quite obviously not :-) think of a bow (with arrows) or a golf club
shaft, or even the tip section of a fishing rod :-)
--
Cheers,

John B.

[James]

So your earlier statement that frames are not designed for "infinite
life" of 10 million cycles wasn't the whole story.

It's dangerous making such sweeping statements.

FWIW I would say the loads I apply are representative. I weigh about
75kg and I sustain over 200W on many long rides. I was racing this bike
at A grade club level too, and won a number of races. Now I ride on
roads that are in poor repair. I dodge potholes but there are patches
galore. In parts it is like riding cobbles. I often have to bunny hop
over obstacles as well. Though this bike is not used for hauling
camping gear, it has survived well over 10 million pedal cycles during
its intended use. What more can you ask?

--
JS

[Axel Reichert]

James <james.e...@gmail.com> writes:

> So your earlier statement that frames are not designed for "infinite
> life" of 10 million cycles wasn't the whole story.
>
> It's dangerous making such sweeping statements.

I stand to the following "sweeping statements":

1. Frames are not designed for infinite life (this holds true for many,
if not most products).

2. Newer research indicates that neither steel nor titanium have
infinite life.

3. Point 2 is more of academic interest for frames, because of point 1.

4. Both points 1 and 2 invalidate the "folk wisdom" that "steel frames
last forever": Neither does the material, nor does the design.

I hope this clarifies things.

Of course from this does not follow that frames cannot last long. Some
brands design them to survive 100000 cycles of 1200 N into the bottom
bracket. I wrote more about this in

Message-ID: <m2r1kmh...@axel-reichert.de>

here in this group.

> I sustain over 200W on many long rides

Together with your mentioned cadence of 80/min and a crank length of 170
mm that averages to 140 N on the crank arm. This is far less than the
1200 N mentioned above, and consequently you should expect your frame to
last much longer than 100000 crank revolutions with your typical ride
loads. The caveats on misuse cases and multi-axial complications still
hold, but I do not see any contradiction here.

Best regards

Axel

[Tom Kunich]

The SKIN of a B52 has been changed several times on the B52H but the airframes which are aluminum, are the same as manufactured almost 80 years ago. The airframe is not particularly strongly built from my perspective of crawling back and forth on the platform to and from the tail gunner's position on bomb runs.

[James]

On 26/6/21 6:52 pm, Axel Reichert wrote:
> James <james.e...@gmail.com> writes:
>
>> So your earlier statement that frames are not designed for "infinite
>> life" of 10 million cycles wasn't the whole story.
>>
>> It's dangerous making such sweeping statements.
>
> I stand to the following "sweeping statements":
>
> 1. Frames are not designed for infinite life (this holds true for many,
> if not most products).

If "infinite life" is defined as "10 million cycles", and those cycles
are well within the endurance limit of 30ksi for steel (something you
don't mention), according to the link you previously posted, then the
frame I am riding has already lasted an "infinite life".

https://en.wikipedia.org/wiki/Fatigue_limit#/media/File:S-N_curves.PNG

>
> 2. Newer research indicates that neither steel nor titanium have
> infinite life.
>

Where?

> 3. Point 2 is more of academic interest for frames, because of point 1.
>
> 4. Both points 1 and 2 invalidate the "folk wisdom" that "steel frames
> last forever": Neither does the material, nor does the design.
>
> I hope this clarifies things.

Not really. Are you now adding oxidation to the reasons that a frame
wont "last forever", which I am taking as 10 million cycles per the
definition you mentioned for "infinite life"?

Clearly my steel frame has not rusted sufficiently to break yet, but
sure that might be the cause of failure one day.

What material or design does "last forever"? What if I throw it into an
acid bath? Or salt? Or a furnace? I mean, the list of caveats might
be infinite!

>
> Of course from this does not follow that frames cannot last long. Some
> brands design them to survive 100000 cycles of 1200 N into the bottom
> bracket. I wrote more about this in
>
> Message-ID: <m2r1kmh...@axel-reichert.de>
>
> here in this group.

That email address doesn't help me find what you wrote.

Is 1200N peak or RMS?

>
>> I sustain over 200W on many long rides
>
> Together with your mentioned cadence of 80/min and a crank length of 170
> mm that averages to 140 N on the crank arm. This is far less than the
> 1200 N mentioned above, and consequently you should expect your frame to
> last much longer than 100000 crank revolutions with your typical ride
> loads. The caveats on misuse cases and multi-axial complications still
> hold, but I do not see any contradiction here.

So again average is not peak. I would expect the stress limits to be
the peak cyclic stress applied.

The peak is likely to be about 1.4 times the average, so more like 200N.

In any case, you didn't define a load for the "infinite life". I said
the loads I apply are probably "representative" of normal use, so by
taking that as the designed cyclic load limit, my frame has survived an
"infinite life" already - by your definition of "infinite life".


Of course most frame building materials can be used in a design that
lasts this long. Even aluminium will be fine to 10 million cycles if
the stress is kept well below 20ksi, according to that wikipedia graph,
and it is not thrown into a furnace or attacked by chemicals or dented
or scratched....


--
JS

[John B.]

Really Tom? The skin on a B-52 is changed? Of course a B-52 or any
other modern airplane is built as what is called a "Monocoque
structure" where the "skin" is the major structural member. So if you
"take the skin off" the whole damned thing will collapps.

As for crawlling back and forth? Oh, now you have become a tail
gunner? Goodness that was quick wasn't it. First you were a helper to
a more skilled airman, carrying his tools, and then Bingo! you become
a gunner. Never having been trained as a gunner.

But then, I guess it sounds very manly down the VFW with the other
drafftees, drinking and telling lies.
--
Cheers,

John B.

[Tom Kunich]

I sort of agree with you. I would like to see ANY research that would say that 30% max strength loadings on steel or titanium would EVER cause fatigue failures.

[Tom Kunich]

Please continue to pretend that you have any knowledge at all about the B52H's which have always had skin plates replaced on a normal schedule and now have those plates changed from aluminum to carbon fiber. You make such an ass of yourself expounding on your ignorance.

They are presently about to replace the engines with the more powerful commercial aircraft engines, build more hardpoints on the wings so that hey can carry ultrasonic missiles for standoff bombing and re-designate the models B52J. You should be so knowledgeable about B52's that you can tell us the engine numbers and what the expected additional lifespan of the B52J will be. I would like to watch the drool coming out of your mouth as you google like crazy to find anything to prove your worthless point. You know nothing at all that isn't on Google and you want to present that as somehow being the truth when more than 50% of the Google reports are outright lies designed entirely to promote a political point of view. Guess what John, you don't live here, you don't vote here, no one cares what you think.

[jbeattie]

Ti frames can fail, even good ones. https://www.ticycles.com/services#services-main I'd be more interested in the failure rate of Douglass or Airborne frames rather than the fatigue limit of Ti or 3/2.5 tubing.

-- Jay Beattie.

[Tom Kunich]

I have seen failures like that but I do not believe those are fatigue failures but design flaws. That fork of mine was NOT well designed but it would have never failed if it had the right leg actually glued on rather than simply riveted. The other side - constructed properly broke halfway down the leg from overload.

[Jeff Liebermann]

On Sun, 27 Jun 2021 10:05:33 -0700 (PDT), Tom Kunich
<cycl...@gmail.com> wrote:

>I sort of agree with you. I would like to see ANY research that would say that 30% max strength loadings on steel or titanium would EVER cause fatigue failures.

It's more like 30 to 60% of ultimate tensile strength:
<https://bike.bikegremlin.com/11144/bicycle-frame-materials-explained/#2.5>
"To make things more interesting, steel and titanium
have a threshold, such that any force lower than the
threshold can exert an unlimited number of cyclic loads,
without the material breaking ever! This threshold is
called fatigue limit (it’s usually between 0.35 and
0.6 times tensile strength)."

It's also not that simple. This video explains it quite nicely, along
with how the S-N (stress_range and number_of_cycles_to_failure) works,
low and high cycle fatigue, infinite fatigue life, Goodman-Haigh
diagrams, and other fatigue related topics.

Note that you cannot simply pull numbers from a published S-N curve
for a given material. That would yield the stresses and number of
cycles for a 50% chance of failure. What you want is something like a
1% chance of failure, which is two standard deviations of plotted data
less (shifting the S-N graph downward).

Understanding Fatigue Failure and S-N Curves (8:22)
<https://www.youtube.com/watch?v=o-6V_JoRX1g>

"Bicycle frame materials - explained"
<https://bike.bikegremlin.com/11144/bicycle-frame-materials-explained/#2.5>

I couldn't find a single S-N curve graph comparing titanium, steel,
aluminum, and carbon fiber. The best I could do are steel, aluminum:
<https://bike.bikegremlin.com/wp-content/uploads/2021/01/s-n-curves-material-fatigue-steel-aluminium.png>
carbon fiber:
<https://www.researchgate.net/figure/Comparison-of-the-fatigue-life-diagram-for-unidirectional-carbon-epoxy-and-carbon-PEEK_fig15_312849090>
and titanium alloy:
<https://www.researchgate.net/figure/SN-curve-of-Ti6Al4V-alloy_fig2_285384606>

This curve is rather interesting:
<https://www.researchgate.net/figure/Comparison-of-steel-and-aluminum-fatigue-behavior_fig1_322220529>
Note that the curve for steel goes horizontal after a certain number
of cycles. That's the fatigue limit for steel. As long as the stress
range is below the horizontal part of the curve, the steel will last
forever. That's the infinite fatigue or endurance limit. However,
also note that the aluminum curve does not go horizontal but continues
downward as the number of cycles increase. Eventually, aluminum will
break, even if there is very little applied stress. That's why
aluminum frame airplanes fall apart after a predictable number of
flights, even if did nothing more than touch and go takeoffs and
landings. Notice that carbon fiber and titanium alloy curves have the
same problem.


--
Jeff Liebermann je...@cruzio.com
PO Box 272 http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann AE6KS 831-336-2558

[Tom Kunich]

Who is surprised that your reference says, "Fatigue strength – endurance
Steel has a fatigue limit. This means: if you design the frame so that its peak loads are below a certain magnitude (relative to its tensile strength) – it will last forever!"

"With this kind of a “safety margin”, aluminium frame will still have a finite endurance, but that limit could go to about 500 years of avid cycling – not bad?"

"Like steel, titanium has a fatigue limit. If you design the frame so that its peak loads are below a certain point (relative to its tensile strength) – it will never break."

It is no surprise that people that use Google never bother to even read what they are citing. This is a demonstration of the foolishness of trying to look experts at things they actually know nothing about. Jeff and John both work very hard to appear to be experts at things that they know nothing about.

[John B.]

On Sun, 27 Jun 2021 10:22:32 -0700 (PDT), Tom Kunich

Nope Tommy, just like your 20 BPM pulse rate You just don't know what
you are talking about.

Please feel free to provide anything other then your delusions to
prove your point.

>They are presently about to replace the engines with the more powerful commercial aircraft engines, build more hardpoints on the wings so that hey can carry ultrasonic missiles for standoff bombing and re-designate the models B52J. You should be so knowledgeable about B52's that you can tell us the engine numbers and what the expected additional lifespan of the B52J will be. I would like to watch the drool coming out of your mouth as you google like crazy to find anything to prove your worthless point. You know nothing at all that isn't on Google and you want to present that as somehow being the truth when more than 50% of the Google reports are outright lies designed entirely to promote a political point of view. Guess what John, you don't live here, you don't vote here, no one cares what you think.

Lets see now... You have been out of the Air Force (if you ever were
in the Air Force) since about 1966 but you know all about the current
modifications the B-52's are undergoing?

Perhaps the Air Force calls you up every morning to tell you what is
going on?
--
Cheers,

John B.

[Axel Reichert]

Tom Kunich <cycl...@gmail.com> writes:

> On Sunday, June 27, 2021 at 10:43:25 AM UTC-7, jbeattie wrote:

[...]

>> Ti frames can fail, even good
>> ones. https://www.ticycles.com/services#services-main

[...]

> I have seen failures like that but I do not believe those are fatigue
> failures but design flaws. That fork of mine was NOT well designed but
> it would have never failed if it had the right leg actually glued on
> rather than simply riveted. The other side - constructed properly
> broke halfway down the leg from overload.

This reminds me on

https://en.wikipedia.org/wiki/No_true_Scotsman

Simplified summary: "Ti will not fail under fatigue." "It does, see
here." "That was a bad design."

My (trivial) point is that a fatigue life depends on both the material
and the design. Which is why people analyze/simulate these things. If
you can reliably predict in advance where and when fatigue failure will
occur, you can change the design.

Like the Principia frame story: 6 prototypes with the same tubing, only
different welding details/designs. 5 failed after (roughly) 30000 cycles
under 1200 N into the bottom bracket, one survived 170000 (numbers from
memory, the original article of efbe.de is gone). That design went into
production.

Best regards

Axel

[Ade]

On 26/06/2021 01:35, John B. wrote:

> On the other hand, I worked on a DC-3, in Vietnam that was made in
> 1936 so about 32 years old at the time and I believe that they are
> still in use... some 80+ years after first being introduced.
>
> All aluminum too :-)
>

Yes, aluminium can be designed to withstand stress cycles in the
billions, or any suitable big number, as long as the stress is low enough.

The problem with bike frames is that the thinner the tubes the higher
the stress. So the lightweight aluminium bike will not withstand
billions of stress cycles.

This is fine as long as the bike is replaced or not used much. But both
my recent lightweight road bikes failed after about 4 years, 10,000 miles.

With my last frame failure I claimed on the guarantee and was given a
carbon frame as a replacement. My suspicion being that the few people
who do ride their bikes enough to fatigue them are deliberately given a
new frame material which does not have the same fatigue limit problem.

i.e. cheaper for manufacturers to replace a few frames than to design a
durable frame.

[Tom Kunich]

I'm not saying that Ti, aluminum or even steel do not fail from fatigue. I am saying that the lives of these metals are extremely long - much longer than the pretense that they fail all the time.

You cannot show obvious construction flaw failures and use that as proof that we have fatigue failures in those metals, and we have to also submit that these fatigue failures are hardly ever catastrophic.

Carbon fiber failures are almost NEVER from fatigue since it doesn't fatigue. But the RESIN does. More importantly you cannot discover construction flaws without ultrasonic testing and this is only done on Look and Time as far as I know. (Maybe Giant but I have seen massive Giant failures that are obvious large air gaps in the layup. But this might have been a bike missed by their QC.) These days it appears that frame construction depends largely on manufacturing care more than testing. Is this a good idea? I don't know, I don't have access to company records.

[Axel Reichert]

James <james.e...@gmail.com> writes:

>> 2. Newer research indicates that neither steel nor titanium have
>> infinite life.
>>
>
> Where?

There are big scientific conferences about this topic, see here

https://dspace.ub.uni-siegen.de/bitstream/ubsi/1170/1/VHCF7.pdf

Page 4 onwards, diagram on page 7 for a titanium example.

Chapter 1 of

Metal Fatigue: Effects of Small Defects and Nonmetallic Inclusions

by Yukitaka Murakami might also be interesting. A more comprehensive
literature survey is here:

https://trace.tennessee.edu/cgi/viewcontent.cgi?referer=http://trace.tennessee.edu/&httpsredir=1&article=1563&context=utk_chanhonoproj

An overview:

https://www.sciencedirect.com/science/article/pii/S2095034915301434

> Are you now adding oxidation to the reasons that a frame wont "last
> forever", which I am taking as 10 million cycles per the definition
> you mentioned for "infinite life"?

No, this is not necessary, see the linked research. You might want to
google for VHCF or "gigacycle fatigue".

> the list of caveats might be infinite!

In contrast to the life. (-;

But again, not needed. These are carefully controlled experiments.

>> Message-ID: <m2r1kmh...@axel-reichert.de>
>>
>> here in this group.
>
> That email address doesn't help me find what you wrote.

It is a "Message-ID", not an e-mail address. A good newsreader allows
accessing stuff by this.

> Is 1200N peak or RMS?

I think it was peak.

> In any case, you didn't define a load for the "infinite life".

No need for the quotes here. 10 million cycles is a pretty standard
definition. It does not come from the top of my head. Some decades back
people thought (because the Woehler curves flatten at about this cycle
number for steel) that they are safe past 10 million cycles (if they
stay below the stress corresponding to this number of cycles). They
could not do more cycles easily. This is now possible, and, bingo, they
found that the Woehler curves are not yet horizontal. There are even
materials, such as Nitinol (used for stents) that have multiple
plateaus.

Best regards

Axel

[Tom Kunich]

That appears to be very special cases Axel, ultrasonic vibrations, while present in a bicycle are extremely low levels and occur at frequencies lower than their test frequencies of that article. I think that article is more applicable to rocket or jet engines. It is speaking about growth of microscopic imperfections and that requires frequencies with wavelengths of 1/2 the diameter of the imperfection.