Replies to post #70391 on Tesla Inc (TSLA)

[boston745]

I believe Tesla has indirectly acknowledged that it's vehicles have low frequency quasi DC EMI issues when it announced the Cybertrucks exoskeleton was a low carbon stainless steel that will be cold worked. Then followed that by announcing it was assembling a team of materials specialist to essentially port the exoskeleton to its other vehicles.

Before we delve into the specifics of the Cybertrucks exoskeleton, and one of its hidden features, we should establish what geomagnetic induced currents are and that they are one of the potential sources of interference during enhanced geomagnetic activity.

GIC are often described as being quasi direct current (DC), although the variation frequency of GIC is governed by the time variation of the electric field. For GIC to be a hazard to technology, the current has to be of a magnitude and occurrence frequency that makes the equipment susceptible to either immediate or cumulative damage.

GIC modelling and simulation are typically below 50 mHz.

Essentially, when the earths geomagnetic field is disturbed sufficiently, it causes currents to run in the earths soil. As these current flow they emit magnetic fields. Those fields interact with conductive materials on and in the earth. That's when GICs arise. The magnetic fields from the earth's surface interact with surrounding magnetic fields and conductive surfaces (most commonly discussed are the electric grid and pipelines) sending electrons moving. In pipelines, these currents increase corrosion, reduce pipeline lifespan, and increase failure rates. In the electrical grid it generally causes transformers to overheat and fail. It's this interaction I believe is the primary source of interference in Teslas causing numerous glitches in multiple systems culminating in worst case scenarios of causing the Tesla to go out of control and/or spontaneous combust.

What then is the best material to shield these low frequency quasi DC electromagnetic fields? Lets examine 3 main properties best seem to aid this: Material, carbon content, & permeability.

1. Material

Using thick conductive metal material such as steel, which often works well, but the drawback is the weight. Aluminium or magnesium are much lighter than steel, but they have insufficient low-frequency shielding properties and, therefore, cannot be used in this application.

Generally, below 100 kHz, steel achieves much greater attenuation than copper.

2. Carbon Content

low carbon steel is typically specified for DC and low frequency magnetic shielding high permeability and saturation point than high-carbon steel

3. Permeability

Magnetic field lines prefer to travel in materials that have certain magnetic properties, namely materials with high permeability. By placing a material of high permeability (or at least a permeability higher than the region in question) around the region you wish to shield, you effectively offer the field lines a better path to travel.

Conclusion:low carbon ferromagnetic steel

Now lets determine what the Cybertrucks exoskeleton is made of to see if it's a low carbon ferromagnetic steel.

“We’re rapidly changing alloy constituents and forming methods, so traditional names like 304L will become more of an approximation.”

What is 304L?

Alloy 304L a T-300 series stainless steel austenitic, which has a minimum of 18% chromium and 8% nickel. Type 304L has a carbon maximum is 0.030

1. Steel - check
2. Low Carbon - check
3. Permeability - uncheck

Probably the most important feature for shielding against quasi low frequency DC EMI is not provided by austenite steels which are a paramagnetic steel more than ferromagnetic. Case closed right? What about the fact Tesla is cold working the steel, what does that do?

Impact of Cold Working Stainless Steel

Any process which can change the crystal structure of stainless steel can cause austenite to be converted to the ferromagnetic martensite or ferrite forms of iron. These processes include cold working and welding. It is also possible for austenite to spontaneously convert to martensite at low temperatures. To complicate matters further, the magnetic properties of these alloys depend on the alloy composition. Within the allowed ranges of variation of Ni and Cr, significant differences in magnetic properties may be observed for a given alloy.

There you have it folks. Cold working 304L (30X) steels causes them to convert to martensite which changes the stainless steel from a paramagnetic material to a ferromagnetic one with high permeability needed for attenuating low frequency EMI. Also of note, tweaking the chromium and nickel levels can enhance this further. Remember what Elon said, they're tweaking with the formulation so that 304L is an approximation. Check!


Conclusion

The fact that Tesla has chosen a very low carbon steel, is cold working, and tweaking the formula, means its creating close to the best low frequency EMI shielding material (which is why its being used on the starship as well).
Then shaping the steel in the fashion it is, like a shell, will allow the magnetic fields to flow along the exterior successfully shielding the interior. The flat planar panels should work to reflect some EM energy like the stealth fighters do.

The "Cybertruck Shell"

Thus, a shell of high permeability material built around an area will effectively keep most of the magnetic field lines in the actual shell itself and out of the area inside the shell.

What might that look like?
https://www.kjmagnetics.com/images/blog/article2010.01.pic3p.gif

If Tesla really believes the Cybertrucks exoskeleton will provide EMI shileding, shouldnt it want to use the material on its other vehicles as well?

The team has been focused on creating new alloys for its products, like new aluminum alloy for casting larger parts in Tesla vehicles or new stainless-steel alloys for SpaceX’s starship and Tesla Cybertruck’s exoskeleton.

Now, we learned that Tesla is creating a new Materials Applications Team to help integrate those new materials faster.

Discussion:
As you can see, the facts support that Tesla knows electromagnetic interference is causing problems in its vehicles and it has a plan to combat it starting with the Cybertruck.
Elon Musk has already stated that the cybertruck has hidden benefits and I believe the evidence supports the Cybertruck has an EMI shielding exoskeleton.
Unfortunately this does not help every current and future owner of the current iterations of any of the S3XY models. Thus, they and the general public, are put at risk. That is not acceptable!

Quote sources:

1.https://en.m.wikipedia.org/wiki/Geomagnetically_induced_current

2.https://incompliancemag.com/article/low-frequency-magnetic-fields-in-electric-vehicles/

3.https://mri-q.com/uploads/3/4/5/7/34572113/lindgren_metals_used_for_rf_shielding.pdf

4.https://www.uu.edu/dept/physics/scienceguys/2004Feb.cfm

5.

We’re rapidly changing alloy constituents & forming methods, so traditional names like 304L will become more of an approximation

— Elon Musk (@elonmusk) July 21, 2020

6.https://www.pennstainless.com/resources/product-information/stainless-grades/300-series/304l-stainless-steel/

7.https://www.greenwoodmagnetics.com/resource/what-is-the-difference-between-304-and-316-stainless-steel/

8.https://www.uu.edu/dept/physics/scienceguys/2004Feb.cfm

9.https://electrek.co/2021/04/22/tesla-creates-new-team-accelerate-use-materials-products/

[Marketing101]

Hard to prove neglegence in court, it hasn't been done yet. And, all auto makers have similar lawsuits against them, nothing here is of any greater risk to this company's ability to make tens of billions of dollars a year.