TeeEmCee, this issue is haunting me.
Today a manufacturing industry magazine I follow posted a technical article describing differences in thermal expansion for different materials. 30 minutes later and I'm sucked in after finding even more relevant material online - Thermo-Mechanical Coupled-Field Analysis of Car Front Bumper by Finite Element Approach.
Thermal Expansion | Dover Motion
https://www.ijert.org/research/ther...y-finite-element-approach-IJERTV3IS111223.pdf
What's interesting is many of these studies were performed with 30-50° temperature gradients. This is what lead me to believe strange things can happen due to a 70-90° temperature gradient - cold 20° battery plugging in to 120 kW supercharger until battery is hot enough that cooling turns on (115-120°). I won't bore you with calculations, but this results in significantly more displacement than an ICE car with steel panels and a much smaller temperature gradient.
It's evident a panel in the floor is flexing a few millimeters creating the popping noise. My Tesla service advisor claims they have a solution for the popping. What's ironic is the second link contains a study where the obvious was concluded - adding more clips to restrain mating parts will limit movement. I'm sure this is part of Tesla's solution.
I stand by my previous point that my car is accident (and scratch) free and any movement in the front fascia is a result of loosely toleranced parts of various materials.
With very different coefficients of thermal expansion it is very difficult for the following mating parts to REMAIN in alignment during extreme changes in temperature without additional supports/clips.
1. Aluminum hood
2. Polycarbonate head lights
3. Plastic bumper
4. STEEL quarter panel
Something to think about if you have to continue taking your car back for work...still undecided if I'll accept Tesla's offer to realign my front fascia in fear of creating another problem.