Comments by "Ken Smith" (@kensmith5694) on "Solar Eclipse Timer" channel.

  1. Early on, I suspected the failure would turn out to be at the titanium ring. This is where there is a transition of materials and temp-co etc. In pressure hulls I have seen that were taken to failure, the failure seemed to always have started at some area of transition.
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  2. For this sort of duty at the least, the fiber should have been "wet" when it is put on. The idea is that you have a situation where everything is swimming in resin. You don't want even small air bubbles in the material. You also didn't cover the fiber directions. They put no angled fibers on. It was all 0 and 90 degree fibers.
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  3. At some point the fibers broke. By then the situation was already bad. The way this sort of thing fails is that the tube goes a little out of round. Think of the pressure pushing in on all sides of a circle. If it remains a circle all will be well. Now imagine the circle is a little out of round. The part where the curve is decreased from the normal curve of a circle is easier to push inwards
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  4. I have some experience with composite pressure hulls. I think (without testing it) that they would have been far better off to have ground the entire surface to make it very smooth (other than the roughness needed for the glue) and the wall thickness very constant before the next layer was applied. Giving a very uniform surface to the next layer to be formed over is important. Defects tend to grow so you don't want even the slightest defect before the next layer. The 0, 90 degree winding as described sounds wrong to me and so does the "45 degree" added layers. You are working on a surface that is not flat and other considerations come into it. I won't do the math but I think that the 53 degree winding method would be better in this case.
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  5. I do disagree with how the joint was made and also from tests I have seen, failures to tend to happen at points of transition.
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  6.  @Everett-xe3eg  You do know that NASA backed away from this thing. This is not their design.
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  7. That would have cost more but it might have worked better. I saw a thing where someone made engine parts out of JB Weld and they worked
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  8. A strong type of steel would have been good too and at a lower cost.
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  9. I think "wet winding" would have been the only way to go. If you do the winding with all air excluded and resin basically dripping off, the "voids" would not be full of air but rather have just a little less fiber in the resin.
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  10. Those layers were mostly under compressive loading. What wonder about is how the sealed the "end grain" where it met the titanium. That is a place where the glue between layers and water coming in from the end can meet. Any void in that area can let water get into between layers and this would be a bad thing.
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  11. The fiber makes the composite stiffer. Remember that the failure was not likely to be simple compression. Some part of the system went out of round It didn't crush to nothing. It was more like flattening a tube. Going out of round tends to be a process that feeds on its self. You want the material to be very stuff to fight this.
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  12. Yes a strong grade of steel or aluminum would likely have worked better. You need it to be stiff so 60 or 70 series aluminum would be needed
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  13. The company that made it likely didn't want the bad press.
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  14. I don't think that would have helped much. A support would need to be a disk of material with perhaps a good sized hole in the middle. A thin ring won't be stiff enough. Remember that a small motion is all it takes to get the full failure.
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  15.  @pocpic  I have built systems with composite pressure hulls. Metal was no allowed for technical reasons but expensive equipment was at risk. They did go deep and cycled many times.Composites can be very stiff for their weight.
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  16. I disagree slightly with your reasoning but not your conclusion. What is happening before we get to failure is going to matter more than the point of actual failure. The direction of the fibers is the direction in which the hull is stiffest. Where the grinding happened, this direction is not following the circle around the tube. Under pressure this area will compress more along that direction taking the tube out of round. This increases the stress. Even if the failure strength of the material was constant and the same in all directions, you have more stress in one area and this is likely to make that area fail first.
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  17. Actually no. Composite pressure hulls are a bit of strange science. As you add layers, each new layer adds less and less additional strength even if the layers are perfect. With defects, it is worse.
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  18.  @klardfarkus3891  The pressure hulls I put electronics in have taken a great many cycles to quite deep in the ocean. Composites do work for the job.
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  19. The units don't matter in this case. Wrong is wrong in any system of measures
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