Just ramblin.
Tearing or cracking starts at little spots that don't show up in normal FEA models. A sharp edge, a minor gap in a weld, a small notch, etc. The narrower and deeper it is, the worst. Cracks start failures.
Square plates without large corner radii should fail at the pointy corners. Oval plates should be harder to tear with the same surface area. Modern epoxy should perhaps be stronger than welding when having to attach to thin wall material. Small areas of welding errors create stress risers. But doing a good job of gluing isn't easy. For those who don't know, modern aircraft are often glued together, and IIRC, so are newer Ferrari's.
When we did our our cage we had to to the body for 2 bars. So we made the bars redundant. We Y-tubed the main hoops so it attaches in 2 planes, and then put in kick bars to attach the bottoms, then extra 45° bars to do the job of the two bars attached to the body. The back bars (attached to body), are not adding any strength at that point. The NHRA allows you to remove those bars IF YOU do extra bracing as of 2008(?).
However, our truck is "heavy" compared to a car. So the extra tubing made sense, even if it hurts our drag race ET's, it will be much stronger than the minimums, perhaps twice as strong.
