One of our customers makes vibration welding fixtures... We had a tour of their facility when we had our training and they were setting up a fixture to sonic/vibrate weld the 2020 Cadillac rear taillight assembly... They ran one for us when we were there... It's amazing that they can vibrate it and weld it in about 10 seconds...
They originally made speakers and one of theirs is shown in one of the old WWII movies with their logo on it... They found out once by accident that the vibrations from the noise could generate heat when someone leaned against something after one of their speakers was run... That began their start into sound/vibration heating and welding...