Cybertruck design conversations

glhs837

Power with Control
No, brittle failure it isn't inherent to aluminum, it is inherent to castings. This is why I hate cast metal for anything that requires structural integrity. Even an alloy with a yield point and ultimate tensile point so close together as 7075 experiences ductile failure.

Hitting a curb isn't fast enough to be considered a shock load either.
If it doesn't fail that way in anything other than a crash scenario does it matter?
 

glhs837

Power with Control
Cast rims have been known to break from hitting a pothole, is that a crash scenario?

Nope, and I wouldn't expect the cybertruck ones to do so. So far we have one truck with a broken rim, and it was smashed into a jersey barrier pretty hard.
 

glhs837

Power with Control
This just popped up in my feed.


See, like Vrai, I always look for the rest of the story.

Since the insurance paid for it, I won't comment on how it was driven; it was just that a very large pothole in our washed-out road caused all the dominoes to fall.

This right raised my radar. Seems like "This is the story I sold the insurance company so I cant change it."

Follow it over Reddit.... Also has some pics



Well damn. Insurance fraud. The guy posted in August that he did this while jumping the truck! 22ft..

Which seems like a more likely way to cause the damage seen.
 

PeoplesElbow

Well-Known Member
See, like Vrai, I always look for the rest of the story.



This right raised my radar. Seems like "This is the story I sold the insurance company so I cant change it."

Follow it over Reddit.... Also has some pics





Which seems like a more likely way to cause the damage seen.

I can't find anything verifying this other than a reddit post. Not saying it isn't true.

One thing you can't deny is how castings fail compared to forged aluminum and that parts are cast for economic reasons, not strength or durability.
 

glhs837

Power with Control
I can't find anything verifying this other than a reddit post. Not saying it isn't true.

One thing you can't deny is how castings fail compared to forged aluminum and that parts are cast for economic reasons, not strength or durability.
Well, it contains more details than the article that seem to line up. And it seems reasonable that such damage is more likely to come from a large jump than a pothole.

You design the part for the task. If the only time it breaks is when its taken outside of design parameters, then you chose the right material. If a test equipment rack inside a test aircraft fails during a 20 crash landing, you cant say that the steel chosen was a poor choice, since the spec says the design must withstand a 16g crash load.

The thing to do look at it logically. Is it logical that a pothole caused that much damage to this one truck, with over 30,000 others running around none of them have failed in the same way? Possible the Meg of potholes did this? Sure? More likely a jump did it, IMO
 

PeoplesElbow

Well-Known Member
Well, it contains more details than the article that seem to line up. And it seems reasonable that such damage is more likely to come from a large jump than a pothole.

You design the part for the task. If the only time it breaks is when its taken outside of design parameters, then you chose the right material. If a test equipment rack inside a test aircraft fails during a 20 crash landing, you cant say that the steel chosen was a poor choice, since the spec says the design must withstand a 16g crash load.

The thing to do look at it logically. Is it logical that a pothole caused that much damage to this one truck, with over 30,000 others running around none of them have failed in the same way? Possible the Meg of potholes did this? Sure? More likely a jump did it, IMO
Usually with design of things like aircraft and automobiles when failures occur the wrong inputs were chosen to design to, very complex shapes etc cause the design to have no analytical solution, then approximate modeled solutions are sought and factors of safety are put on them. For stuff like airframes the factor of safety is very small because that means more weight and possibly cost. You have to plan for what can't be planned for, in the case of trucks I would say more so than econoshitboxes or sports cars and even more so for something that is supposed to be bullet proof and a "truck for the apocalypse".

I would hope the repair folks would be able to tell if the truck was jumped or hit a pothole, damage from jumping it would most likely be more symmetrical and a pothole on one side of the vehicle.

I know I've hit potholes hard enough that I have no idea how i didn't get a flat from them because it hurt my back and teeth.
 

glhs837

Power with Control
Usually with design of things like aircraft and automobiles when failures occur the wrong inputs were chosen to design to, very complex shapes etc cause the design to have no analytical solution, then approximate modeled solutions are sought and factors of safety are put on them. For stuff like airframes the factor of safety is very small because that means more weight and possibly cost. You have to plan for what can't be planned for, in the case of trucks I would say more so than econoshitboxes or sports cars and even more so for something that is supposed to be bullet proof and a "truck for the apocalypse".

I would hope the repair folks would be able to tell if the truck was jumped or hit a pothole, damage from jumping it would most likely be more symmetrical and a pothole on one side of the vehicle.

I know I've hit potholes hard enough that I have no idea how i didn't get a flat from them because it hurt my back and teeth.

Yep. But we don't know for sure what he did. So we can't say if it was outside parameters. He convinced the insurance company it was a pothole in any case. Symmetry of landing depends on takeoff angle and loading. I suspect we'll know more at some point.
 

PeoplesElbow

Well-Known Member
Yep. But we don't know for sure what he did. So we can't say if it was outside parameters. He convinced the insurance company it was a pothole in any case. Symmetry of landing depends on takeoff angle and loading. I suspect we'll know more at some point.
I hope so, engineering failures are one of my interests especially material related stuff.

Another non-related example of a poor choice of material I will pick on Toyota here. Ever notice older Toyotas usually have yellowed/cloudy headlights, whoever picked what material to use for their headlights should be kicked in the ass. Every Toyota I've owned had this problem, every Ford I ever owned the headlights remained crystal clear. Toyota's choice of material most likely met the requirements set forth, in my opinion they defined the problem incorrectly and ended up with an incorrect solution.
 

glhs837

Power with Control
I hope so, engineering failures are one of my interests especially material related stuff.

Another non-related example of a poor choice of material I will pick on Toyota here. Ever notice older Toyotas usually have yellowed/cloudy headlights, whoever picked what material to use for their headlights should be kicked in the ass. Every Toyota I've owned had this problem, every Ford I ever owned the headlights remained crystal clear. Toyota's choice of material most likely met the requirements set forth, in my opinion they defined the problem incorrectly and ended up with an incorrect solution.
Sometimes it's literally just a "Will it be a problem before they get out of warranty" math based choice.

Ford made a section of the Explorers tailgate out of plastic for a while. You will often see them with vertical cracks.

I'm also interested in "generational failure" items when the whole industry jumped on a bandwagon and they all had issues. The knock on effects can be interesting. My 87 GLHS had a bad steering rack in the early 2000s. There were a few rebuilds around but no place to rebuild mine.

Seems there was a change in racks in the mid eighties. Caused enough problems that a whole aftermarket industry solely devoted to rebuilding racks sprang up. But once the problems were identified and fixed, and the initial bow wave of racks were fixed, not enough business to keep them all going so the bottom dropped out.

Late 90s, a lot of maker switched to a mild steel for brake and fuel lines. 10 years later they were all rusting. Caught the bow wave of that wit my 99 Blazer. Long brake line ruptured right ahead of the rear axle splitter block. No pre-bent lines then, but now you can get them for everything now.
 

PeoplesElbow

Well-Known Member
Sometimes it's literally just a "Will it be a problem before they get out of warranty" math based choice.

Ford made a section of the Explorers tailgate out of plastic for a while. You will often see them with vertical cracks.

I'm also interested in "generational failure" items when the whole industry jumped on a bandwagon and they all had issues. The knock on effects can be interesting. My 87 GLHS had a bad steering rack in the early 2000s. There were a few rebuilds around but no place to rebuild mine.

Seems there was a change in racks in the mid eighties. Caused enough problems that a whole aftermarket industry solely devoted to rebuilding racks sprang up. But once the problems were identified and fixed, and the initial bow wave of racks were fixed, not enough business to keep them all going so the bottom dropped out.

Late 90s, a lot of maker switched to a mild steel for brake and fuel lines. 10 years later they were all rusting. Caught the bow wave of that wit my 99 Blazer. Long brake line ruptured right ahead of the rear axle splitter block. No pre-bent lines then, but now you can get them for everything now.
When was the last time you seen an early 2000s Chevy pickup with the plastic part around the tailgate handle still in place?
 
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