I'm re-quoting Sandro's photo, because this is a good illustrative example of Richie's/Chris' build. Note the driver's side full-up "NASCAR" on the left side; right side is a single-tube bar bisecting another bar to create an "X". Richie did not have a horizontal bar at the bottom.
I think something here is being overlooked. We should be looking at the car as a sacrificial anode in that the structure successfully absorbed the force of impact which allowed the driver to survive.
By your description of the force of impact, it sounds like the cage did a good job of absorbing the energy. Is there really a design that's practical in weight and material cost that can withstand any possible impact ? And how should it look after an incredible impact ? I wouldn't expect it to look like it did before the accident.
I suspect you don't understand the full scope of what happened to Richie's car. If Richie had been 180 spun around with the x-bar on the driver's side,
he would be dead today.
Period.
There was absolutely ZERO space between the passenger side door and the exhaust tunnel. Zero. The passenger side door was halfway into the car, and only inches from hitting the driver, thankfully on the other side of the car.
A lot of people like to get into a discussion of "crush zones" and "energy absorption" and the like, but we don't have the tools to be able to quantify that. As such, it becomes more an "art" than a science. And without a survival cell, absorbing energy kinda doesn't matter. Granted, dying of a detached brain is just as dead as being crushed, but given the choice I think I'd rather take my chances with g-forces.
Finally, while this discussion centers around a crushed passenger side, my focus is how we should design a proper driver's side crash structure.
The design you show does appear to be a stronger way to make an X. I'm sure that at an 80 mph direct impact there would be some failure somewhere in that construction too.
Of course. But this particular door structure failed in tension, and failed in a way we cannot accept.
Let me make this clear: I am not hammering Chris' work.
In point of fact, my Nissan NX2000 has a (highly more structural) x-bar design
on the driver's side. But, my point is that the design as illustrated above in Sandro's photo can withstand exactly half the tensile forces of a true double bar.
Think of it this way: let's say you cut that "X" out of there and hang a car from it; how much force can it withstand? Only as much force as one tube. Why only one tube, you ask? Because its weakest place is in the middle, where there's only the cross-sectional area of one bar. If, however, you were to weld a plate across the face of that "X" it could withstand twice the load, because it's now being distributed among two tubes.
A "taco" gusset would not do the same thing, unless it were also welded across the face. The purpose of gussets is not to increase tensile strength but to support the tubes in a bending moment. For the purposes of the discussion at hand, two plates welded across the back and face of the "X" would be just as effective.
It is somewhat bothersome that this incident took the force in the door alone rather than using the crush structure of the rocker and floor. Given IT cage rules I do not know how to change that.
Well, as you know, the best thing would to be allowed to weld to the rocker panel. But trying to get that IT rule changed would be Sisyphian. As a compromise, I'm envisioning using the plate are rule to extend the plates as far towards the center of the door as possible, then welding tubes to that. Kessler always added a longitudinal bar at the bottom on my cars (similar to Sandro's photo, above) but I think we might expand upon that a bit more.
Does anybody know anything about the driver that hit him?
I saw Richie talking to him in impound, looked fine. Front-end damage on the 'Ta didn't seem significantly worse than other bad SM wrecks...that car seems to handle hits pretty well.
I am the one who built the cage in Richies car. I wish Rich had let poeple photo the damage as that is the only way we all learn.
I chatted with Richie about it, but he wanted to discuss it with you first. If you can talk him into letting one of his guys take some photos to post here (or you take some when you see it), I think we can all really learn from it.
Honestly, Chris, there was really nothing you could have done differently to the passenger side to affect a significantly different result; it was that hard a hit. All I'm offering here is a detailed discussion of the failure mode and how we might apply that to our driver's side going forward.
This is timely, as we've got a new car build going to happen this winter. I'm personally no longer a fan of the pure "X" bar on the driver's side, though I'm not clear exactly how far towards the "NASCAR" I'm wanting to go...
