Nonlinear acoustics for practical applications

Three different ultrasonic nonlinearity parameter measurement methods are available: the capacitive detection method to measure absolute values of nonlinearity parameters; the laser interferometry detection as a non-contact method; the contact piezoelectric transducer based relative measurement method. Among all these three methods, the contact piezoelectric transducer detection method has been used as the most practical approach due to its operational simplicity for materials damage assessments. One of the main drawbacks of this technique, however, has been the low sensitivity of the receiving transducers, especially for the second harmonic signals, causing a high uncertainty in measurements. In this work, it is demonstrated with a copper [100] single crystal that a couple of high Q-value band-pass filters and a low-noise preamplifier introduced in the system not only improve the measurement accuracy but also make it possible to determine absolute values of nonlinearity parameters without using the complex capacitive detection method.