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In this design, the wall thickness is only large where the bolt tension is acting, saving quite a lot of mass. This also gives the bolts lots of thread length to engage with.
The FEA was set up with the face that contacts the forward closure fixed. The 4330 lb force is acting upward on the top surface of the bolt holes and 960 lb shear force acts radial outward on eaach hole to simulate the bolt tenion. The safety factor is 2.27.
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