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Pesqueeb

Pesqueeb

bicycle in airplane hangar
Feb 2, 2007
42,579
20,171
Riding past the morgue.
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4xBoy

4xBoy

Turbo Monkey
Jun 20, 2006
7,478
3,628
Minneapolis
Pesqueeb said:
Boeing's civil aviation division kills people for profit with documentable regularity and has never had a problem with it. So for them be saying even they thought this boat was sketchy is pretty damning. :rofl:
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Boeing hasn't killed billionaires before, just little people.
 
Jm_

Jm_

sled dog's bollocks
Jan 14, 2002
20,591
11,083
AK
Pesqueeb said:
Boeing's civil aviation division kills people for profit with documentable regularity and has never had a problem with it. So for them be saying even they thought this boat was sketchy is pretty damning. :rofl:
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One could say the Titan had un-commanded pitch down...
 
Toshi

Toshi

butthole powerwashing evangelist
Oct 23, 2001
40,375
9,205
Pesqueeb said:
Are you a wizard?

futurism.com

OceanGate CEO Bragged About Using Expired Carbon Fiber

OceanGate CEO Stockton Rush reportedly used expired carbon fiber that was "past its shelf life" to build the doomed Titan submersible.
futurism.com futurism.com
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it was on the twitters

where I also found out that this was probably prepregnated carbon weaves as those adhesives have a Boeing-determined shelf life, and that use of such expired prepreg is super common in the Formula SAE world... where the stakes for failure are much, much lower, of course.
 
jonKranked

jonKranked

Detective Dookie
Nov 10, 2005
89,604
27,802
media blackout
Toshi said:
it was on the twitters

where I also found out that this was probably prepregnated carbon weaves as those adhesives have a Boeing-determined shelf life, and that use of such expired prepreg is super common in the Formula SAE world... where the stakes for failure are much, much lower, of course.
Click to expand...
Note re: shelf life - expired doesn't inherently mean something is bad, typically it just means there's no data to support saying something is still good.
 
Toshi

Toshi

butthole powerwashing evangelist
Oct 23, 2001
40,375
9,205
4xBoy said:
Well, now we know what it isn't good for after expiration date.
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to be fair, the fundamental design flaws probably were much greater factors in the failure than the slightly less sticky than spec glue
 
kidwoo

kidwoo

Artisanal Tweet Curator
Aug 25, 2003
42,149
13,358
Squirtin ketchup n' mustard on charred flesh
Toshi said:
it was on the twitters

where I also found out that this was probably prepregnated carbon weaves as those adhesives have a Boeing-determined shelf life, and that use of such expired prepreg is super common in the Formula SAE world... where the stakes for failure are much, much lower, of course.
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how dare you call loss of advertising space low stakes!
 
Westy

Westy

the teste
Nov 22, 2002
56,562
22,659
Sleazattle
jonKranked said:
Note re: shelf life - expired doesn't inherently mean something is bad, typically it just means there's no data to support saying something is still good.
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This ain't no can of beans sitting on a shelf. It is the epoxy in the pre-preg that expires and it's properties over time is studied to absurd levels. As soon as the pre-preg is made that epoxy starts to cure. You can slow that down by putting it in a freezer but the cure rate for specific temperatures is very well known. Add to that the epoxy has to do a lot more than just get hard. It is heated slightly when applied so it sticks, preventing voids and the fibers from wrinkling or moving out of position. When it is cured in an autoclave the temperature is brought up slowly as the epoxy needs to transition to a viscous state and flow into voids before getting hard (hee hee). Not of that happens as expected if it has passed a certain age/cure leading to fiber wrinkles, voids and possible delaminated layers.

When you see a composite bike that breaks from JRA, more likely to be from a manufacturing defect as described above than bad design or material choice.

Also composites are great for pressure vessels in tension, but not in compression. Dumb material for the application. Making something designed to sink out of light weight materials then strapping tons of ballast to it doesn't make much sense.
 
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rideit

rideit

Bob the Builder
Aug 24, 2004
25,242
12,874
In the cleavage of the Tetons
Serious question here, but should I apply heat to the surfaces of what I want to epoxy together with a heat gun before putting them together? What would the ideal temperature be?
I have a project coming up where I want to epoxy a thin steel plate to some glass.
 
Westy

Westy

the teste
Nov 22, 2002
56,562
22,659
Sleazattle
rideit said:
Serious question here, but should I apply heat to the surfaces of what I want to epoxy together with a heat gun before putting them together? What would the ideal temperature be?
I have a project coming up where I want to epoxy a thin steel plate to some glass.
Click to expand...
Probably not necessary but especially if you can clamp the two pieces together while it cures. You may want to find a way to scratch the glass to give it some texture for the epoxy to get a grip on. Lapping compounds or even some very course buffing compounds for auto paint can do this.
 
Adventurous

Adventurous

Starshine Bro
Mar 19, 2014
11,031
10,278
Crawlorado
rideit said:
Serious question here, but should I apply heat to the surfaces of what I want to epoxy together with a heat gun before putting them together? What would the ideal temperature be?
I have a project coming up where I want to epoxy a thin steel plate to some glass.
Click to expand...
Why would you do that? So long as the bonding surfaces are clean and adequately scuffed that should be sufficient.
 
jonKranked

jonKranked

Detective Dookie
Nov 10, 2005
89,604
27,802
media blackout
Westy said:
This ain't no can of beans sitting on a shelf. It is the epoxy in the pre-preg that expires and it's properties over time is studied to absurd levels. As soon as the pre-preg is made that epoxy starts to cure. You can slow that down by putting it in a freezer but the cure rate for specific temperatures is very well known. Add to that the epoxy has to do a lot more than just get hard. It is heated slightly when applied so it sticks, preventing voids and the fibers from wrinkling or moving out of position. When it is cured in an autoclave the temperature is brought up slowly as the epoxy needs to transition to a viscous state and flow into voids before getting hard (hee hee). Not of that happens as expected if it has passed a certain age/cure leading to fiber wrinkles, voids and possible delaminated layers.

When you see a composite bike that breaks from JRA, more likely to be from a manufacturing defect as described above than bad design or material choice.

Also composites are great for pressure vessels in tension, but not in compression. Dumb material for the application. Making something designed to sink out of light weight materials then strapping tons of ballast to it doesn't make much sense.
Click to expand...
yea i didn't presume this was one of those scenarios, there's lots of things that degrade over time in a manner that would prevent them from functioning as intended but in general the notion that expired = instant death is silly.
 
Jm_

Jm_

sled dog's bollocks
Jan 14, 2002
20,591
11,083
AK
Westy said:
Making something designed to sink out of light weight materials then strapping tons of ballast to it doesn't make much sense.
Click to expand...
Well, for fail-safe I'd think the opposite would be true. If possible, you'd want it lighter (like a bathyscaphe ), so it's natural inclination is to go up, not down. Ultimately that's what you want it to do. Sinking is the easy part.
 
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Westy

Westy

the teste
Nov 22, 2002
56,562
22,659
Sleazattle
Jm_ said:
Well, for fail-safe I'd think the opposite would be true. If possible, you'd want it lighter (like a bathyscaphe ), so it's natural inclination is to go up, not down. Ultimately that's what you want it to do. Sinking is the easy part.
Click to expand...
Yeah you want buoyancy to return to the surface but that isn't difficult to add cheaply by other means. But perhaps they didn't get cheap discarded materials for that.
 
Jm_

Jm_

sled dog's bollocks
Jan 14, 2002
20,591
11,083
AK
I think the right thing to do now is build a new pressure vessel to Oceangate specs, repeatedly dunk the thing on a cable to the same depths, do NDT between each dive, test till failure to find the failure mode.
 
canadmos

canadmos

Cake Tease
May 29, 2011
22,497
22,315
Canaderp
Jm_ said:
I think the right thing to do now is build a new pressure vessel to Oceangate specs, repeatedly dunk the thing on a cable to the same depths, do NDT between each dive, test till failure to find the failure mode.
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Or just move on and stop wasting tax dollars figuring out what we already know happened to a privately funded vessel.
 
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