Cybertruck hitch analysis by Engineering Explained

[cybercricket]

Aircraft also have a limited lifetime. After a certain amount of hours, they are just, done.

Technically so do most road vehicles. For ICE it's based on the engine wear after certain number of miles, and for BEV it's dictated by the battery pack even if sometimes both can be repaired / replaced.

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[Gaximus]

Technically so do most road vehicles. For ICE it's based on the engine wear after certain number of miles, and for BEV it's dictated by the battery pack even if sometimes both can be repaired / replaced.

Right but you can replace both of those things, and keep using the frame. Aircraft fuselage can get to a certain number of pressurizations and it would be illegal to fly. I’ve seen trucks driving around from the 1940’s.

 

[cybercricket]

I think the intent was to say that other elements may not have been stressed to the point of damage yet may contribute to the load capacity of the hitch/ casting.
I tend to agree and think the C pillar/mast -> sail -> tower -> casting is an important load path.

Did it not ultimately fail at the protrusions on the aluminum casting ? Stress on the entire casting isn't the question here.

 

[cybercricket]

Right but you can replace both of those things, and keep using the frame. Aircraft fuselage can get to a certain number of pressurizations and it would be illegal to fly. I’ve seen trucks driving around from the 1940’s.

I don't know how that stuff works in practice, so I will defer to you if you do. How do they get super old planes restored and flying ?

 

[Gaximus]

I don't know how that stuff works in practice, so I will defer to you if you do. How do they get super old planes restored and flying ?

The very old planes usually don’t have pressurized cabins. And there are waivers you could get for historic planes. But I doubt the FAA would grant those for passenger carrying aircraft.

 

[mongo]

Did it not ultimately fail at the protrusions on the aluminum casting ? Stress on the entire casting isn't the question here.

It first failed at the welds between the casting and tailgate towers before snapping. Without the sail panels, those wouldn't have been stressed and the system would have failed earlier. (Unless there is some other tower load path I am missing)

 

[cybercricket]

The very old planes usually don’t have pressurized cabins. And there are waivers you could get for historic planes. But I doubt the FAA would grant those for passenger carrying aircraft.

Cool. I was thinking that procedures exist to restore/re-certify the airframes, but they would be impractical for serially-produced aircraft especially as there is wear on other components and them becoming simply outdated after that many hours. I've seen some restoration videos of helicopters where compromised airframe elements were identified and repaired, I don't know if there is a difference with the fixed wing machines.

 

[cybercricket]

It first failed at the welds between the casting and tailgate towers before snapping. Without the sail panels, those wouldn't have been stressed and the system would have failed earlier. (Unless there is some other tower load path I am missing)

I don't see how that contradicts anything. As the receiver is loaded, the force is transferred onto the casting and then distributed to the rest of the vehicle. Then as the force increases, the weakest link will be first to go and it didn't happen to be the aluminum protrusions. The point remains that since those protrusions aren't reinforced in any way through the rest of the vehicle, and the receiver itself isn't attached to anything else in addition, the force to break them will be more or less constant and independent of how the rest of the vehicle is built.

I would also add that spot welds are likely to have a significantly wider range of force tolerance to failure than the castings. So on this particular unit spot welds failed first, but on the next it could be the other way round.

 

[mongo]

I don't see how that contradicts anything. As the receiver is loaded, the force is transferred onto the casting and then distributed to the rest of the vehicle. Then as the force increases, the weakest link will be first to go and it didn't happen to be the aluminum protrusions. The point remains that since those protrusions aren't reinforced in any way through the rest of the vehicle, and the receiver itself isn't attached to anything else in addition, the force to break them will be more or less constant and independent of how the rest of the vehicle is built.

I would also add that spot welds are likely to have a significantly wider range of force tolerance to failure than the castings. So on this particular unit spot welds failed first, but on the next it could be the other way round.

I guess I don't understand what your point is.
The last things to fail were the protrusions because they were not under much stress until the tower connection failed.
If one removed the sails then reran the test, I think it would fail much sooner.
Are you saying that is irrelevant because the towers connect to the main casting?

 

[cybercricket]

I guess I don't understand what your point is.
The last things to fail were the protrusions because they were not under much stress until the tower connection failed.
If one removed the sails then reran the test, I think it would fail much sooner.
Are you saying that is irrelevant because the towers connect to the main casting?

Yes.

 

[mongo]

Yes.

If the system is weaker without the sails, how can they be irrelevant? The poster's point (I think) was that they added to the strength.

 

[cybercricket]

If the system is weaker without the sails, how can they be irrelevant? The poster's point (I think) was that they added to the strength.

Imagine hypothetically that it was the bolts that failed before anything else. Would he argue that the failure point of the bolts was dictated by the rest of the vehicle ? What if the welds failed in some (same) spot, and then these bolts failed second, same question.

 

[Bridgeboy69]

Others have already done an excellent job of explaining where you are wrong, (and why Grok, and other "AI" summaries are just aggregators and not the final word on anything), but I think the above bolded section says it all.

I disagree. ??‍
?

For my part I will admit that saying the side panels contribute "nothing" was an exaggeration. "Minimal" would have been more accurate, just like the body panels on any unibody vehicle contribute "something" to the structure. That doesn't make it an exoskeleton.

OK, your admittance is noted and appreciated.

I will also admit that I do not know, and did not know, the extent of the “exoskeleton’s” contribution to the structural integrity of the vehicle. It’s not something I want to even spend the time to understand, or speculate upon, because I really don’t care to that level to devote that much time to it.

LULWUT?

OK, having trouble comprehending? See layman’s analogy here:

when a single link breaks in a chain, the fact that all the other links did not fail proves they did not contribute in resisting the load.

Hope that helps you understand!

I think the intent was to say that other elements may not have been stressed to the point of damage yet may contribute to the load capacity of the hitch/ casting.

I tend to agree and think the C pillar/mast -> sail -> tower -> casting is an important load path.

Exactly, but sort of. I am not trying to be a Monday morning quarterback…errr…structural engineer, on this one, like @cybercricket seems to be and perhaps a few more of you. I know when I am both out of my lane, and out of time and patience to pursue something dreamed up by someone to test and abuse a component to the point of failure and post it online in a YouTube video. I don’t pretend to know, or have spent any appreciable time trying to educationally “guess” the load path or probable weak points in a system designed by Tesla engineers, likely, in a very advanced computer modeling system. I don’t choose to spend my time attempting to replicate that advanced computer program’s ability to design and calculate loading on all of the complex elements “just in my head” and then spout on an online forum like I know what I am talking about. Because I don’t, and I don’t believe for a second any of you do either, despite what level of education or life experience you have, besides applying basic engineering principles and knowledge of load paths, knowledge of certain welds integrity, etc.

If you all want to spend your weekends and other spare time debating back and forth the potential reasons why this hitch failed in a single abused-until-failure experiment performed by a YouTuber, then go for it, whatever floats your boat. But I consider this an exercise in futility, and I would rather spend my time enjoying my Cyberbeast. I will comment in generalities, because that is all that I am qualified to do, but I’m not going to analyze this failure in detail because I consider that a complete waste of time.

Imagine hypothetically that it was the bolts that failed before anything else. Would he argue that the failure point of the bolts was dictated by the rest of the vehicle ? What if the welds failed in some (same) spot, and then these bolts failed second, same question.

I wouldn’t argue anything because this is a waste of time.

You want to act like you know how this complicated set of composite metals (even single metal castings) behaves but you don’t know. You can guess all you want with your repertoire of engineering knowledge which basically means jack-shit in this analysis just as mine does.

What do you think suspensions do? Besides the obvious, which is to reduce and soften dynamic loads on passengers, they also reduce, and soften, dynamic loads on other structural components. Every structural component in a system acts like a spring, or suspension if you will, to some degree along any load path…as everything deflects when introduced with a load, but you already know that, right?

There will always be some weak link, some weakest point, that will fail, Always. But when that weak point fails, it does not exclude all the other components in the complex, synergistic, system which contributed to prolonging (or accelerating) that failure.

 

[cybercricket]

I wouldn’t argue anything because this is a waste of time.

You want to act like you know how this complicated set of composite metals (even single metal castings) behaves but you don’t know. You can guess all you want with your repertoire of engineering knowledge which basically means jack-shit in this analysis just as mine does.

What do you think suspensions do? Besides the obvious, which is to reduce and soften dynamic loads on passengers, they also reduce, and soften, dynamic loads on other structural components. Every structural component in a system acts like a spring, or suspension if you will, to some degree along any load path…as everything deflects when introduced with a load, but you already know that, right?

There will always be some weak link, some weakest point, that will fail, Always. But when that weak point fails, it does not exclude all the other components in the complex, synergistic, system which contributed to prolonging (or accelerating) that failure.

Your response is just a version of an "appeal to authority." Have a nice day.

 

[mongo]

Imagine hypothetically that it was the bolts that failed before anything else. Would he argue that the failure point of the bolts was dictated by the rest of the vehicle ? What if the welds failed in some (same) spot, and then these bolts failed second, same question.

Oh, are you saying the stength of the casting at the projection is independent of the rest of the system?
That's true, and the projections on their own have a failure point (possibly much) less than 10k.

The failure of the hitch as a whole was dependent on all the pieces. Had the spot welds not failed at 10k, then the casting projections would also not have failed at 10k. As long as the towers and sail were intact, the casting projections were primarily under compression, once the spot welds failed, it was subject to a bending moment beyond its ability to react.

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