Franz von Holzhausen throwing a steel ball at the Tesla Cybertruck's side window and breaking it, despite the fact that it was supposed to deflect it, went viral for all the wrong reasons. However, even though the window failed the ball test, Tesla will still install laminated armored glass on its truck and thanks to newly released patents, we now know more about how this multi-layered glass works.
The patent states that it should be able to withstand a 2 Joule impact, with only a 10 percent chance of failure (that means it has an IK07 impact protection rating). This means it should be not fail when a 0.5 kg (1.1 pound) mass is dropped on it from 40 centimeters (15.8 inches) nine times out of ten.
It works thanks to the use of several different sheets of glass - the inner pane is chemically treated to improve its flexibility and strength and it is joint through an adhesive layer (that has energy absorption properties) to the outer pane, which is made from borosilicate (glass that has boric oxide in it) and this is supposed to make it better at resisting thermal shock.
According to Teslarati, the patent points out that Tesla's reasoning for using this advanced type of glass mostly has to do with day to day use. The manufacturer won't equip the Cybertruck with it because it wants occupants inside to pe protected from actual projectiles being fired at the vehicle. Instead, the idea is to prevent rock chips from happening and thus lengthening the lifespan of the glass. This is especially true of the windshield that is most vulnerable to chips and quite difficult and expensive to replace.