Elastic convolution effect on the solid interface

The second-harmonic generation due to the interface nonlinear effect was studied theoretically and experimentally. Two ultrasonic shear wave beams of 7.7 MHz were incident from the glass side to the glass-iron interface in opposite directions with the same incident angle. The interface elastic nonlinear interaction produces a beam of a longitudinal wave of 15.4 MHz normal to the interface. The received longitudinal wave has a triangle shape as the input tone burst waves have a rectangular modulation.. The time delay is reasonable. The output amplitude relates to the input in a square law. The influence of the transducer positions shows that the phenomenon is due to the interface effect. The convolution efficiency is about -106.6 dBm when the apertures of the beams have not been compressed