With this rigid non denting exoskeleton, what does that mean for occupants in a collision? Did they test it like the glass windows?
No crumple zone?
- Thread starter odguy
- Start date
Interesting point and wished Elon would have addressed that. Maybe there is enough absorption inside to protect the occupants.
I was wondering about the glass too. People carry those break glass things that probably won't work here.
I mentioned this on Reddit as well. Someone mentioned it could very well still crumple beyond something like a sledgehammer hit, and whatever is behind the stainless panel might factor in.
Still, seems odd. Can't wait for crash safety ratings.
Still, seems odd. Can't wait for crash safety ratings.
Yeah normally during their reveals they mention the crash testing or on the product page they boast the crash safety of the vehicle. None of that today...
I think the stainless steel skin is dent resistant, but will still deform under crash forces. Saying it's cold rolled implies some kind of work hardening but think work hardened steel can still bend and break. I wonder how their ultrasonic sensors work through the stainless steel vs. the aluminum of the Model X.
Yea the force of a hand swung hammer is exponentially minuscule compared to the force of a collision. So there is little to no correlation in crash testing.
My guess is the crumple zones will be where the need to be. Length wise is where you need crumple zones, you don't necessarily need/want crumpling to happen width wise.
You still want some side impact energy absorption but there are structural steel elements that protect occupants on the doors.
Skotty
2014 S P85 | 2020 3 P19"
I think they are still working on this product. Expect changes.
Pros:
Specs look good. Hauling capability seems similar to a top end F-250. Range is good. Price is good.
Full length bed.
Built in outlets, bed ramp, and possibly air compressor. Nice additions.
Impact resistant.
Potential capability for lift to increase for offroad and decrease for highway travel.
Ability to lower for loading bed.
Likely to far exceed other pickups -- even electric ones -- on efficiency.
Cons:
Exoskeleton will clash with safety concerns (the crumple zones question). I think Tesla will work on this, but it will be difficult for them to balance. They can make it crumple on front, and I think that is what they will do. Back would be nice too, but pickups on the road today don't provide bed crumple (not as far as I've seen, anyway), so that is not required to meet current standards.
Looks are polarizing. Looks are partially due to material use; will require a more chiseled look like we saw. They are going Blade Runner on this, and that's a fair strategy, but I don't know if people will buy into it or not.
Paint options. They will either have to go DeLorean on this, or provide a special flexible paint with clear coat to help resist paint damage and preserve the impact resistance appeal, or allow impact resistance appeal to be compromised by knowledge that it won't help preserve the paint.
Tough glass, if they can perfect it, will butt up against concerns from some corners about ability to break glass intentionally. Safety orgs may want alternative for removing/breaking window.
Bed loading pictures will be heavily criticized by those who don't realize the air suspension is doing that intentionally; enough PR/education can overcome this and make it a potential pro though.
Expectation/Prediction:
This vehicle will not be a slam dunk like the S and 3. It will be a modest success more like the X.
Hm... lets see, will this follow the Star Trek success pattern?
Star Trek 1 / Roadster
Star Trek 2 / S
Star Trek 3 / X
Star Trek 4 / 3
Star Trek 5 / Y (maybe not fair, Y could be a big hit)
Star Trek 6 / Roadster V2
Star Trek Generations / Cybertruck
Star Trek First Contact / ? (need a big success here)
Pros:
Specs look good. Hauling capability seems similar to a top end F-250. Range is good. Price is good.
Full length bed.
Built in outlets, bed ramp, and possibly air compressor. Nice additions.
Impact resistant.
Potential capability for lift to increase for offroad and decrease for highway travel.
Ability to lower for loading bed.
Likely to far exceed other pickups -- even electric ones -- on efficiency.
Cons:
Exoskeleton will clash with safety concerns (the crumple zones question). I think Tesla will work on this, but it will be difficult for them to balance. They can make it crumple on front, and I think that is what they will do. Back would be nice too, but pickups on the road today don't provide bed crumple (not as far as I've seen, anyway), so that is not required to meet current standards.
Looks are polarizing. Looks are partially due to material use; will require a more chiseled look like we saw. They are going Blade Runner on this, and that's a fair strategy, but I don't know if people will buy into it or not.
Paint options. They will either have to go DeLorean on this, or provide a special flexible paint with clear coat to help resist paint damage and preserve the impact resistance appeal, or allow impact resistance appeal to be compromised by knowledge that it won't help preserve the paint.
Tough glass, if they can perfect it, will butt up against concerns from some corners about ability to break glass intentionally. Safety orgs may want alternative for removing/breaking window.
Bed loading pictures will be heavily criticized by those who don't realize the air suspension is doing that intentionally; enough PR/education can overcome this and make it a potential pro though.
Expectation/Prediction:
This vehicle will not be a slam dunk like the S and 3. It will be a modest success more like the X.
Hm... lets see, will this follow the Star Trek success pattern?
Star Trek 1 / Roadster
Star Trek 2 / S
Star Trek 3 / X
Star Trek 4 / 3
Star Trek 5 / Y (maybe not fair, Y could be a big hit)
Star Trek 6 / Roadster V2
Star Trek Generations / Cybertruck
Star Trek First Contact / ? (need a big success here)
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Crumple zones are mostly about front and rear impacts and a more rigid stainless steel skin doesn’t change this much, it still deforms under impact along with the structures under it. Impact has a lot more energy than a sledge hammer.
Side impact safety is very much helped by rigidity, that’s why the battery pack improves side impact safety so much, because it doesn’t cave in. There isn’t much room to let the other vehicle come into the passenger compartment if you’re t-boned without doing harm. You can see the videos of the difference where a Tesla doesn’t cave in on side impacts. The thick rigid skin connected to the heavy battery pack would likely make this better.
Side impact safety is very much helped by rigidity, that’s why the battery pack improves side impact safety so much, because it doesn’t cave in. There isn’t much room to let the other vehicle come into the passenger compartment if you’re t-boned without doing harm. You can see the videos of the difference where a Tesla doesn’t cave in on side impacts. The thick rigid skin connected to the heavy battery pack would likely make this better.
I think with safety being Tesla’s #1 priority and the fact that each vehicle released has proven the safest in class leads me to assume Tesla has the safety aspect covered. I would be surprised if the Cybertruck wasn’t safest in class as well.
I know the term "exoskeleton" implies no interior structure but has that been confirmed? I haven't been able to watch the unveiling yet. Did they say there's actually no interior structure the stainless steel attaches to? It will be an interesting engineering feat to route wiring harnesses, airbags, window mechanicals, and all the other stuff that gets attached to a frame if there's only a rigid skin.
I would assume there is a tubular structure internally. Furthermore, given that the steel is 3mm thick, I assume that there are ‘channels’ on the inside of the sheet steel that are thinner, thereby creating an opportunity for the sheet metal to crumple in a pre-ordained manner. Much like if you want a piece of corrugated board to fold in a certain way you weaken it on one side and leave the other unaffected.
mspohr
Well-Known Member
It's not a skin attached to a frame. It's a skeleton. The whole thing is a crumple structure. Think of a honeycomb.
Haven't done work with multiphysics solvers which is what they use to analyze crumple zones but if crumple zones are highly dependent on buckling/crippling then I can see it won't be too bad. Buckling is just dependent on stiffness (modulus of elasticity) and geometry which doesn't change when you harden a material.
Modulus of elasticity and even density doesn't change even if you say 30x stainless steel (are dependent on grain structure). I believe crap stainless steel goes down to 20ksi Ftu (Ultimate Tensile Strength) so maybe this steel is around 600ksi Ftu which would makes sense. There are a lot more variables of materials then just Ftu which is what they usually refer to when saying X material is 30x stronger than Y material.
Looking at videos it seems like side impact is mostly just bending which then you probably have to be more clever but I believe its more of an energy problem and not based on small deflections so probably looking more at strain energy.
Once the skeleton gets any damage even in a small crash I can easy see it being totaled. Can't see someone doing any welding or repairs without knowing how the load path or what type of loads are at each segment. SS can be welded but in general the weld strength won't come close to 600ksi Ftu plus surrounding structure would get weaker from the heat.
Modulus of elasticity and even density doesn't change even if you say 30x stainless steel (are dependent on grain structure). I believe crap stainless steel goes down to 20ksi Ftu (Ultimate Tensile Strength) so maybe this steel is around 600ksi Ftu which would makes sense. There are a lot more variables of materials then just Ftu which is what they usually refer to when saying X material is 30x stronger than Y material.
Looking at videos it seems like side impact is mostly just bending which then you probably have to be more clever but I believe its more of an energy problem and not based on small deflections so probably looking more at strain energy.
Once the skeleton gets any damage even in a small crash I can easy see it being totaled. Can't see someone doing any welding or repairs without knowing how the load path or what type of loads are at each segment. SS can be welded but in general the weld strength won't come close to 600ksi Ftu plus surrounding structure would get weaker from the heat.
To absorb energy, you need the material to bend and be permanently deformed, not spring back. When it springs back, the energy is still gong to find its way into accelerating the vehicle violently with you inside of it.
Super hard materials when you exceed their yield point are going to crack and shatter. I am not sure that is as good at absorbing the energy. They may need less-hard portions of the interior structure to make the crumple zones work well.
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