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[CyberGus]

I am just stating what I see.

Clearly.

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[ED_SFO]

After seeing the prototype at the Peterson museum, i can agree that using the thicker SS would be the way to go regarding the warping. The prototype had zero warp anywhere except where they hit it with the sledgehammer, was definitely a mark left there but barely a dent.

 

[anionic1]

You seem defensive for some reason. I am just stating what I see.

I looked back through the thread and i think i meant to say i don't think you are wrong. I completely agree with their statement about the body panels. Sorry for ruffling feathers here. I think its very likely that they reduced the thickness of panels due to the substantial interior body components. i have been saying for a very long time that i think the exoskeleton will play much less a role in the strength than many of the origami believers would have suggested. Really, if we step back, aside from the dramatically innovative castings and structural pack, the rest of the frame is similar to their other vehicles except that the finish exterior body panels are stainless. I am sure they do play probably a larger part in the strength of the body that say the model Y, but the recent images do prove that there is a very substantial interior body, which was highly debated for years.

 

[SparkChaser]

I think you are wrong. Clearly now with the recent photos there is a very substantial inner steel body and the rear castings are clearly supporting much of the load near the sail pillars. Tesla is very obviously making decisions to try to reduce the weight of the truck. They reduced the dimensions by 5%, removed the metal bed and solid surface dash. I bet they are struggling to get to that holy grail of 500 mi range so they are also reducing the panel thickness everywhere except at the doors to maintain the bullet resistant claim

I do not think the production model will be a mix of panel thickness. It is not reasonable. The structural, load bearing skin will be a significant part of the overall integrity of the vehicle. Having a rigid and stable outer skin and a support structure under that will be how all of this is achieved.
The proto type does not need to be as strong and is more of a concept delvery. Having the fully developed engineering is not how the process works. Developing the final form takes lots of trial and error.

 

[Crissa]

I do not think the production model will be a mix of panel thickness. It is not reasonable. The structural, load bearing skin will be a significant part of the overall integrity of the vehicle. Having a rigid and stable outer skin and a support structure under that will be how all of this is achieved.
The proto type does not need to be as strong and is more of a concept delvery. Having the fully developed engineering is not how the process works. Developing the final form takes lots of trial and error.

Also, it would make the truck age weirdly if there was alot of panel thickness variation. There will be some... leading and trailing edges, for instance... that will have transverse strengthening so the skin folds inward instead of peels outwards in crashes.

Remember, the truck has to handle dynamic loads. That the internal layers of the body can stand on their own doesn't mean they handle the load without those layers.

You seem defensive for some reason. I am just stating what I see.

I do not like unsupported conjecture parading as 'clearly apparent' statements.

-Crissa

 

[Crissa]

You seem defensive for some reason. I am just stating what I see.

I do not like unsupported conjecture parading as 'clearly apparent' statements.

-Crissa

 

[anionic1]

I do not like unsupported conjecture parading as 'clearly apparent' statements.

-Crissa

Is it not clearly apparent that there is a substantial interior body inside the SS exoskeleton. The new images are really the first confirmation of that. I thought it made it clearly apparent.

 

[anionic1]

I do not think the production model will be a mix of panel thickness. It is not reasonable. The structural, load bearing skin will be a significant part of the overall integrity of the vehicle. Having a rigid and stable outer skin and a support structure under that will be how all of this is achieved.
The proto type does not need to be as strong and is more of a concept delvery. Having the fully developed engineering is not how the process works. Developing the final form takes lots of trial and error.

The sad part is that we will likely never know about the actual structural loading. Even Munro isn't going to do a structural finite analysis of the structure to determine how much of the load is actually transferred through the exoskeleton. We may get a better idea if they do greatly scale back the thickness of the SS it would give us a very good indication that its not holding much load. It could also be that as they progressed with the casting design they realized that its much more effective to use the casting to transfer the load with less weight than it is to use the skin. With the recent pictures its become very clear that there is substantial interior body/framing.

 

[Crissa]

Is it not clearly apparent that there is a substantial interior body inside the SS exoskeleton. The new images are really the first confirmation of that. I thought it made it clearly apparent.

A few pieces that can barely stand on their own is absolutely no evidence of an internal frame design, let alone that the skin will be no more than any other unibody car.

Hence, unfounded conjecture parading as certain statements. You don't even know what color the body in white will be coated in for the production models because we haven't seen any from production models.

Even Munro isn't going to do a structural finite analysis of the structure...

This is also untrue. What do you think is in the very expensive reports that Munro sells to automotive competitors?

-Crissa

 

[anionic1]

A few pieces that can barely stand on their own is absolutely no evidence of an internal frame design, let alone that the skin will be no more than any other unibody car.

Hence, unfounded conjecture parading as certain statements. You don't even know what color the body in white will be coated in for the production models because we haven't seen any from production models.


This is also untrue. What do you think is in the very expensive reports that Munro sells to automotive competitors?

-Crissa

Do you know what structural finite analysis is?

 

[Cyber_Dav]

Do you know what structural finite analysis is?

I do not, but it sounds really techy, huh?

 

[cvalue13]

Only way I ever understood “exoskeleton” proper would be if the suspension/ground contact attached to the body panels (allowing that those panels could wrap the entire envelope entirely, including underneath). Only then would the panels be carrying the innards, not the other way around.

Instead the innards are carrying the panels

fine by me

 

[JBee]

Exactly. For any structure to carry any load it needs to have something called a "load path". Think of a lever that needs a "fulcrum" to act against to create force at the end. There is no such thing as a lever action without a fulcrum, that resists the forces applied. Likewise also on a vehicle.

In particular @Crissa and @HaulingAss have seemingly no understanding of what this means, and just argue with navel fluff posts, citing "but EM said", or "do you know better than them" arguments.

They both absolutely FAIL at providing any description of how the load is transferred into the skin, and why that is better than through the cast, cabin and pack, that actually supports the vehicle "from the ground up" and also in the case of a crash impact.

There are two distinct main load paths in a vehicle, one is for impact passenger protection, which typically only works well once in it's lifetime, the other is for transferring "operational load" to the tyre contact patch with the road in normal operation, which is what has to work all of it's life.

The only place I know that the "SS skin" contributes to structural "safety" is intrusion protection for the doors, in that the door skin is compressed into the rigid cabin frame safety cell on a side impact. But because they are doors that open, they offer no rigidity to the vehicle whilst under operational loads as they are only hinged.

In general consider this load path sketch:

Note that impacts denote intensity and angle, all of which are transferred through the frame.
The only meaningful "resistance" in an impact is deceleration from mass inertia of the vehicle (the change in motion causes a force to act on the vehicle and deform it) and the vehicles traction to the ground via the tyre contact patches.

It is inherently clear, to some at least, that the most structurally and weight efficient way to achieve this is using very cost effective front and rear casts ($140 each apparently), that can be designed in intricate 3D detail to absorb or deflect any load vector, which a simple 2D skin simply cannot do.

Note: smooth peak free deceleration is the primary objective for passenger safety in an impact, so a uniquely homogeneous compressible structure (think aluminium sponge), that can be made with a cast is significantly more important than a "exoskin".

This same cast structure is also the primary operational pathway for loads to be carried to the wheels in a "non-impact" load path.

Look at the front cast assembly here that supports the front suspension riser and integrates to the rigid cabin frame for rigidity, all completely without interacting with the front fender "skin" that, from that photo at least does not show any structurally meaningful way to attach to a SS skin to transfer loads into the wheels at all. The same is true for the rear cast and bed.

Now if you look at the first diagram again, take note of the suspension riser in the load path, and consider how it coincides with the load path due to vehicle mass or acceleration compressing the suspension. These are both on the same structural member for a reason, and that is to reduce material (cost) and increase rigidity by incorporating two main load paths into one single structure. Now look at the ribbing and strengthening on the front CT cast and how that is transferred into the structural pack and cabin frame. You can literally see the designed load path lines with where the ribbing is.

So, regardless of the exoskin-proflicators on this forum, the skin does in no way constitute the primary structure of the vehicle. The primary structure is simply cabin frame with structural pack (also noteworthy btw for integrating the elements) and the front and rear casts.

In saying that, it is possible that some of the impact loads are transferred through the skin (like the doors etc) but very unlikely that the skin contributes to the operational mass load paths to the wheels, even when considering the torsional, centrifugal or longitudinal loads, even whilst towing, on the vehicle.

Now there is no need to worm one's way out of the factually incorrect statements here, by claiming that "I never said that it was only the exoskeleton", I have saved all the interactions on various threads here as evidence of what ridiculous claims were made. A simple "I was wrong" will suffice. ?

 

[anionic1]

I do not, but it sounds really techy, huh?

Here is an example video. For some reason it won’t let me put a link in from my phone. . If Munro did finite element analysts on the complex shapes of anything he pulls apart I would be extremely surprised. I have seen that they will do chemical analysis and measure thicknesses and determine metal properties etc.
Really only Tesla would have the finite element analysis modeling of the parts. It would take someone doing some extreme scanning and measuring and modeling to try to recreate it. So back to my point, it’s likely that we will never really know how much load the exoskeleton skin is actually bearing.

 

[anionic1]

but the prototype has some, like, 1mm or less panels?

not to suggest anything more than that the prototype construction is a probably a poor gauge of anything about the production model

in any event, I’ve long ago seen some structural engineers who specialize in metal suggest that two common effects were likely to be seen in the CT: oil canning was one

the other was (translating from nerd speak I don’t remember specifically) was basically the noises the flat sheets would make under vibration or jostling - similar to the noises one might hear if waiving around a handsaw. Suggestion was that to avoid this Tesla would need to fill the interior voids with a hardening sort of expanding foam adhesive.

BTW, what did you make of the “sail storage” seam on the original prototype?

I saw that Sean in person. I don’t think anyone has ever seen the sail pillar storage IRL. So it’s likely that it was only actually created in a rendering of the truck. Seeing how beefy that aluminum casting is and the fact that there are these nice clean circular glue ready attachment points on the castings for the SS panels, I would doubt that sail pillar storage is a thing anymore and they may just bend side and combine that sail pillar and quarter panel. My guess would be that will definitely be lighter than 3 mm

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