Cybertruck Crash Test Predictions

[Jhodgesatmb]

You'd be surprised by how many people argue with this point.

Even in this thread, people are talking about the Cybertruck demolishing anything it hits which would, of course, do significant injury to the occupants. People on this board haven't thought through the neck-snapping consequences of an unattenuated crash.

Back to the people who think heavier == safer. Many of them feel that a heavier car itself is more likely to survive the collision undamaged. That's the engineering-ethics discussion I mentioned: it is obvious that an expensive (and insured) piece of machinery should be sacrificial-by-design (via crumple zones) in order to prevent injury to the occupants. However, the "I wish they'd build 'em like they used to" crowd typically hasn't considered the ethics from the perspective of an automotive design engineer who has a say in how tens of thousands of car-crashes unfold.

There is a lot to unpack here, even if you personally accept that proper crash engineering is worthwhile. One could teach a whole university course on these kinds of engineering-ethics questions. Fortunately, this one is easy.

However, as someone who reads other car blogs/forums, this thread contained echoes of some widely-believed fallacies that were truly destructive when they were widely believed. One of those fallacies is that heavier/stronger cars are safer in a collision -- which was demonstrably false in the video I shared. (The Malibu is strong around the passengers, and deliberately weaker elsewhere.)

The idea that crumple zones, seatbelts, and air bags save lives shouldn't be controversial. The data has been in for decades.

And, yet, there is a lot of automotive misinformation out there and there are a surprising number of people who are ready to fight to keep it that way. ??‍

But before the crash got to the dummy the Bel Aire does pretty well. If it had had both the strong chassis/body and the modern features would it not have protected the occupant? Of course we want safety above all else but we want to protect the vehicle from incidental damage and vandalism. Can we have both?

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[Crissa]

Of course we want safety above all else but we want to protect the vehicle from incidental damage and vandalism. Can we have both?

That's irrelevant. Crumple zones have nothing to do with incidental damage and vandalism.

-Crissa

 

[Cyber_Starship]

I've been wondering how the Cybertruck's unique front end design will be engineered to crumple at high speeds.

In low speed collisions I imagine just the shorter hood area will crumple. The Cybertruck's front end is similar in length to ICE pickups, but the A-pillar encompasses where the back half of the hood would normally be. I'm curious if this area can be used to lengthen the deceleration time for high speed collisions and house additional structure for the small overlap. I believe the frunk runs under this area. The downside is this would result in intrusion into the frontal dashboard area, so the airbags or some restraint system would need to prevent limbs from reaching this area. Maybe they'll have a subframe, firewall, crossmember, a-pillar reinforcement, or thicker exoskeleton to separate the safety cell from this area and prevent intrusion into the passenger space.

Here's my simple depiction:

(low speed)

(high speed)

I'm not a structural or crash safety engineer so I could be completely wrong.

 

[Cyberman]

Hey all,

I'm new here and happy to be apart of the Cybertruck "future" owners club.

I've been thinking a lot about how the Cybertruck will do in crash tests. With Tesla having the safest vehicles on the road, I'm hopeful that the Cybertruck will be even safer. Just a few things come to mind with the Cybertruck specifically. With a thick steel exoskeleton, how will the car have any crumple zones?

Would love to hear anyones thoughts on this and their overall crash test prediction!

Best,
Craig

Welcome Craig. As we've discussed in previous threads, those clever engineers at Tesla designed the crumple zone into the other guys' vehicle. This way, the other vehicle is declared a total loss, carry on with your day. Despite the very valid evidence brought by Crissa, I don't see a lot of crumple happening on Cybertruck.
Don't take anything I say too seriously. We're all just trying to stave off insanity while we wait for our Cybertruck. ?

 

[FutureBoy]

We're all just trying to stave off insanity while we wait for our Cybertruck. ?

Some of us more successfully than others. LOL.

I’m one of the less successful ones.

 

[Jhodgesatmb]

That's irrelevant. Crumple zones have nothing to do with incidental damage and vandalism.

-Crissa

Not irrelevant, just not part of the OP’s crumple zone question. And did I say otherwise? I want all of the safety features I can get, but I also want the 3mm stainless steel exoskeleton. My question is, can we have both, and your reply went in another direction.

 

[Luke42]

But before the crash got to the dummy the Bel Aire does pretty well. If it had had both the strong chassis/body and the modern features would it not have protected the occupant?

That's one of the reasons they chose a 2009 Malibu as the modern vehicle.

The Malibu is as close to a Bel Air with modern features as you can get. It's from the same manufacturer (GM), same place in the product lineup, and it solves the same problem for the customer.

Of course we want safety above all else but we want to protect the vehicle from incidental damage and vandalism. Can we have both?

If you can come up with a reusable and cost-effective way to absorb the crash energy that the Malbu's front end handles, then yes. I'm not aware of any engineering solution to this problem, but I'm just a guy with an unrelated STEM-job who remembers a lot of what I read.

Another way to solve this problem would be to make it easy replace the entire car forward of the A-pillar. I wouldn't be too surprised to see this on the Cybertruck, since the structure forward of the A-pillar is simpler than it is on most ICE vehicles. Keep in mind, though, that the passenger-compartment may deform somewhat, even if it protects the occupants.

Lastly, the way we currently solve this problem is actually pretty good. When a car is sacrificed to protect the occupants, we (other insured drivers) collectively buy you a new a car (insurance claim), and recycle what's left of the old car (junkyard). When viewed through a systems-thinking lens, this seems like a pretty-good outcome. But maybe we can do better?

 

[Luke42]

Not irrelevant, just not part of the OP’s crumple zone question. And did I say otherwise? I want all of the safety features I can get, but I also want the 3mm stainless steel exoskeleton. My question is, can we have both, and your reply went in another direction.

It seems reasonable to assume that stainless steel can be sized and shaped so that it will provide crumple zones.

Maybe the stainless steel won't be 3mm forward of the A-pillar? Maybe the stainless steel will be thinner in some places, or pre-scored? But using stainless steel still makes sense, as far as making the CT withstand the test of time.

Sandy Munroe has said some things about "replaceable crash bars", and Tesla seems to take his advice seriously, so they'll probably have some replaceable crash parts.

Will you be able to saw off the structure forward of the A-pillar and replace it (while leaving some visible scars?) I don't know, but it kind-of feels like a Cyber-platform solution to the challenges presented by protecting the occupants, making the vehicle last, and remaining affordable. Replacing large parts of the vehicle (instead of recycling the entire vehicle), strikes me as the most likely improvement over the way we do things now.

(Body shops do currently replace large bolt-on parts on existing cars. Doors and fenders, for instance.)

 

[TheLastStarfighter]

You'd be surprised by how many people argue with this point.

Even in this thread, people are talking about the Cybertruck demolishing anything it hits which would, of course, do significant injury to the occupants. People on this board haven't thought through the neck-snapping consequences of an unattenuated crash.

Back to the people who think heavier == safer. Many of them feel that a heavier car itself is more likely to survive the collision undamaged. That's the engineering-ethics discussion I mentioned: it is obvious that an expensive (and insured) piece of machinery should be sacrificial-by-design (via crumple zones) in order to prevent injury to the occupants. However, the "I wish they'd build 'em like they used to" crowd typically hasn't considered the ethics from the perspective of an automotive design engineer who has a say in how tens of thousands of car-crashes unfold.

There is a lot to unpack here, even if you personally accept that proper crash engineering is worthwhile. One could teach a whole university course on these kinds of engineering-ethics questions. Fortunately, this one is easy.

However, as someone who reads other car blogs/forums, this thread contained echoes of some once-popular fallacies that were truly destructive when they were widely believed. One of those fallacies is that heavier/stronger cars are safer in a collision -- which was demonstrably false in the video I shared. (The Malibu is strong around the passengers, and deliberately weaker elsewhere.)

The idea that crumple zones, seatbelts, and air bags save lives shouldn't be controversial. The data has been in for decades.

And, yet, there is a lot of automotive misinformation out there and there are a surprising number of people who are ready to fight to keep it that way. ??‍

Heavier cars are, by far, safer than lighter cars. This is especially true in car-to-car collisions.

https://phys.org/news/2015-05-heavier-pricier-vehicles-safer.html

 

[Luke42]

Heavier cars are, by far, safer than lighter cars. This is especially true in car-to-car collisions.

https://phys.org/news/2015-05-heavier-pricier-vehicles-safer.html

You're overgeneralizing the results of that study.

It's trivial to make a vehicle heavier without improving crash-safety. This is why older cars (especially those designed before FEA was commonly used) have terrible crash-protection. This matters more than the mass of the vehicle.

If all other things are equal, a bigger vehicle can "win" the collision (which means you're legally liable for the damage done to other people and vehicles). However, it's rare that all other things are equal.

Also, remember that you are legally required pay for any death and destruction you cause in a collision.

 

[TheLastStarfighter]

You're overgeneralizing the results of that study.

It's trivial to make a vehicle heavier without improving crash-safety. This is why older cars (especially those designed before FEA was commonly used) have terrible crash-protection. This matters more than the mass of the vehicle.

If all other things are equal, a bigger vehicle can "win" the collision (which means you're legally liable for the damage done to other people and vehicles). However, it's rare that all other things are equal.

Also, remember that you are legally required pay for any death and destruction you cause in a collision.

I’m not over generalizing anything. Heavier = safer. It’s not a myth. Of course there are many other factors. You are not liable for damage to others, unless you are at fault. I’ve yet to hit someone. I have been hit. If I do get hit, I hope my vehicle is as safe as possible.

 

[VolklKatana]

I've been wondering how the Cybertruck's unique front end design will be engineered to crumple at high speeds.

In low speed collisions I imagine just the shorter hood area will crumple. The Cybertruck's front end is similar in length to ICE pickups, but the A-pillar encompasses where the back half of the hood would normally be. I'm curious if this area can be used to lengthen the deceleration time for high speed collisions and house additional structure for the small overlap. I believe the frunk runs under this area. The downside is this would result in intrusion into the frontal dashboard area, so the airbags or some restraint system would need to prevent limbs from reaching this area. Maybe they'll have a subframe, firewall, crossmember, a-pillar reinforcement, or thicker exoskeleton to separate the safety cell from this area and prevent intrusion into the passenger space.

Here's my simple depiction:

(low speed)

(high speed)

I'm not a structural or crash safety engineer so I could be completely wrong.

This will be interesting because I would assume there is going to be a front casting, much like the MY. The fewer the parts the better from Tesla's perspective, so i would think this would be a definite possibility. As you mentioned @Cyber_Starship im not sure what is left from a crumple zone perspective.

 

[Crissa]

Heavier cars are, by far, safer than lighter cars. This is especially true in car-to-car collisions.

I’m not over generalizing anything. Heavier = safer. It’s not a myth.

It is a myth.

...If you ignore single-car incidents and injuries to others, pedestrians for instance. Large vehicles get into more collisions, as well.

So as a system, they are not safer.

-Crissa

 

[CyberOwl]

I'm worried about shear force transfer during a crash. If it's made structural, the battery casing will be subject to massive forces, and will need to be designed to break away before breaking open.

 

[Crissa]

I'm worried about shear force transfer during a crash.

This will be thought about. The material between the cells is supposed to be rigid and fire/thermal runaway suppressing.
And if the section of the vehicle the batteries is in is subject to sheer forces at failure, you're talking about damage that enters the cabin itself.

-Crissa