Titanic tourist sub goes missing sparking search

[Dan]

This is already posted up-thread.

Sorry about that. Please delete it.

 

[Still Kicking]

I saw an interview with another submersible "pioneer" who said he went on a deep test dive in the Bahamas after Rush's first solo deep dive. Rush warned him that he should expect to hear "fireworks" going off as the hull absorbed the pressure. The interviewee described them as small caliber pistol shots.

If all the warnings from experts in the submergence field didn't give Rush pause, those noises should have. He was beyond reckless.

 

[chillyinCanada]

I saw an interview with another submersible "pioneer" who said he went on a deep test dive in the Bahamas after Rush's first solo deep dive. Rush warned him that he should expect to hear "fireworks" going off as the hull absorbed the pressure. The interviewee described them as small caliber pistol shots.

If all the warnings from experts in the submergence field didn't give Rush pause, those noises should have. He was beyond reckless.

He seems to have believed those were the weak fibers and unnecessary, or some weird statement to that effect. Smh

 

[Gone for diving]

I saw an interview with another submersible "pioneer" who said he went on a deep test dive in the Bahamas after Rush's first solo deep dive. Rush warned him that he should expect to hear "fireworks" going off as the hull absorbed the pressure. The interviewee described them as small caliber pistol shots.

If all the warnings from experts in the submergence field didn't give Rush pause, those noises should have. He was beyond reckless.

So the lesson here is,
when there are no more fibers letting go... the end is near,

Boy do I like steel!!!!

 

[Dan]

I saw an interview with another submersible "pioneer" who said he went on a deep test dive in the Bahamas after Rush's first solo deep dive. Rush warned him that he should expect to hear "fireworks" going off as the hull absorbed the pressure. The interviewee described them as small caliber pistol shots.

If all the warnings from experts in the submergence field didn't give Rush pause, those noises should have. He was beyond reckless.

Indeed, it’s beyond reckless. Those “fireworks” are the sound of the carbon fiber delaminating (breaking up), which is way beyond the yield strength of the material. What I learned in my sophomore year of Materials Science & Engineering in University of California at Berkeley, a safe operation of the material under pressure cycles should be done within the modulus of resilience of the material, the linear zone of stress-strain curve of the material, O to A zone, in the Chicago Cuve figure, below.

Courtesy of Exploring the Stress / Strain Curve for Mild Steel - The Chicago Curve

The maximum allowable working pressure (MAWP) should be at 2/3 of the test pressure. That means if the test is done at 4000 m depth, the MAWP is at 2,667 m depth. If MAWP is at 4000 m depth, you need to test it to 6000 m depth. The test pressure should be under the yield strength (point A in the figure, above), within the modulus of resilience. Those “fireworks” occur at point E in the figure, above. Nuts!

Increasing the MAWP can be done by material thickness and structure (sphere is stronger than cylinder, flat plate being the weakest).

 

[Akimbo]

In the old days (mid 1960 & 70s), most saturation and deep-bounce diving bells were rated for internal and external pressure. I was always MUCH more nervous on one atmosphere/external pressure dives.

The idea was that divers could inspect the worksite at one atmosphere, get geared up, and do a rapid blow down (pressurize) to working depth. ROVs have eliminated that need and saturation has displaced deep mixed gas bounce dives.

 

[Gone for diving]

Indeed, it’s beyond reckless. Those “fireworks” are the sound of the carbon fiber delaminating (breaking up), which is way beyond the yield strength of the material. A safe operation of the material under pressure cycles should be done within the modulus of resilience of the material, the linear zone of stress-strain curve of the material, O to A zone, in the Chicago Cuve figure, below.

View attachment 790484
Courtesy of Exploring the Stress / Strain Curve for Mild Steel - The Chicago Curve

The maximum allowable working pressure (MAWP) should be at 2/3 of the test pressure. That means if the test is done at 4000 m depth, the MAWP is at 2,667 m depth. If MAWP is at 4000 m depth, you need to test it to 6000 m depth. The test pressure should be under the yield strength (point A in the figure, above), within the modulus of resilience. Those “fireworks” occur at point E in the figure, above. Nuts!

Increasing the MAWP can be done by material thickness and structure (sphere is stronger than cylinder, flat plate being the weakest).

I am starting to wonder if it broke longitudinally.
The center of the cyl was bucking inward compared to the ends and breaking the strand side by side,

I still think if he had a bulkhead, in the middle it would have been alot better, or build a reverse tank, carbon fiber and epoxy a 1/4ish ring of titanium over top of it,

But the whole thing seems flawed from the beginning.

 

[Dan]

I am starting to wonder if it broke longitudinally.
The center of the cyl was bucking inward compared to the ends and breaking the strand side by side,

I still think if he had a bulkhead, in the middle it would have been alot better, or build a reverse tank, carbon fiber and epoxy a 1/4ish ring of titanium over top of it,

But the whole thing seems flawed from the beginning.

Longitudinally meaning the straight part of the cylinder? I would think that would be the weakest part of the cylindrical structure. It would be better to make it into oval (like an egg) if spherical is not desirable in terms of maximizing internal cavity for passenger room.

 

[Dan]

I still think if he had a bulkhead, in the middle it would have been alot better, or build a reverse tank, carbon fiber and epoxy a 1/4ish ring of titanium over top of it,

Not sure if I understand what you mean. May be you can draw it up & post the drawing here?

When mixing the materials such as carbon fibers, epoxy and metal (titanium) we need to know the effect of pressure on the material contraction and how much difference their values relative to each other as that would affect the sealing tolerance and we are dealing with high pressure environment (6000 psig) and pessure cycling the materials from 0 to 6000 psig.

 

[tursiops]

Indeed, it’s beyond reckless. Those “fireworks” are the sound of the carbon fiber delaminating (breaking up), which is way beyond the yield strength of the material. What I learned in my sophomore year of Materials Science & Engineering in University of California at Berkeley, a safe operation of the material under pressure cycles should be done within the modulus of resilience of the material, the linear zone of stress-strain curve of the material, O to A zone, in the Chicago Cuve figure, below.

View attachment 790484
Courtesy of Exploring the Stress / Strain Curve for Mild Steel - The Chicago Curve

The maximum allowable working pressure (MAWP) should be at 2/3 of the test pressure. That means if the test is done at 4000 m depth, the MAWP is at 2,667 m depth. If MAWP is at 4000 m depth, you need to test it to 6000 m depth. The test pressure should be under the yield strength (point A in the figure, above), within the modulus of resilience. Those “fireworks” occur at point E in the figure, above. Nuts!

Increasing the MAWP can be done by material thickness and structure (sphere is stronger than cylinder, flat plate being the weakest).

That is the curve and numbers for steel. Other materials are different, perhaps quite different.