Comments by "Ken Smith" (@kensmith5694) on "OceanGate Titan Hull - Hundreds of Ill-advised Carbon Fiber Grind Spots" video.

  1. 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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  2.  @Everett-xe3eg  You do know that NASA backed away from this thing. This is not their design.
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  3. 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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