john force accident and frames
Back to the topic,
I find it negligent on the NHRA's part to even consider heat treated tubing over normalized tubing in these chassis.
I am under the impression that the flex characteristics of the chassis would be the major concern on a longevity point of view not the rigidity angle.
Any one who knows basic metallurgy would know that the more ''stiff'' or ''rigid'' a metal is, the more prone to breakage under cyclic vibrations and as well as side impact loading. I assume their angle would be that the chassis that was built from tubing normalized vs hardened given the same wall thickness would be more prone to unwanted ''flex'' during the course of a run and be more unstable at high speeds, again, i am not a mechanical engineer.
Again, the tested tubing was shown to have an elongation variation of a whopping 18% by the chassis builder, why didn't that raise a big red flag to the NHRA tech people?
It would be impossible to predict the amount of pre and post heat to use in the fabrication and welding process, and that has reared it's ugly head when McClenethan's chassis failed near the weld due to a heat affected zone failure.
It also can be traced back to all of the repairs that were necessary to be done to chassis that were failing due to cracking.
I would bet my bottom dollar that the majority of the problems would disappear with these breakage issues if they eliminated the use of ''hardened'' tubing and went with ''normalized'' tubing exclusively. Too much flex? Increase the wall thickness, and if people complain about the weight, tell them that's too bad when safety is involved.
They are trying to slow the cars down anyway, so what's 30 or so extra pounds?