Why Can Ultrasonic Cleaner Penetrate Tin Foil?

To be precise, ultrasonic waves don't actually "penetrate" the tin foil. Instead, they damage the surface through the physical force generated by cavitation. This process can be understood on three levels:

1. Microjet Impact Mechanism: When bubbles burst near the tin foil surface, they generate microjet streams with speeds exceeding 100 meters per second. These high-speed liquid jets act like invisible "water jets," continuously impacting the tin foil surface, leading to metal fatigue and localized damage.

2. Shock Wave Propagation Effect: The collapse of each bubble is like a miniature bomb, emitting shock waves in all directions. When these shock waves propagate to the tin foil surface, they generate enormous instantaneous pressure, enough to cause perforation at weak points in the foil.

3. Stress Concentration Principle: Microscopic irregularities on the tin foil surface become stress concentration points. Under continuous cavitation, these stress concentration points first develop cracks, which then expand into visible holes.