An experimental technique for the determination of the relative acoustic nonlinearity parameter of materials with Rayleigh waves excited directly is presented.Rayleigh surface waves were directly generated in materials by the specific piezoelectric transducer fixed at the specimen's edge,and were measured with a laser interferometer system.After the Rayleigh wave signals were processed with FFT method,the relative acoustic nonlinearity parameter of materials was then determined from the absolute magnitudes of the fundamental and second harmonics of Rayleigh surface waves.This procedure was used to determine the acoustic nonlinearity parameters of aluminum alloys 2024 and 6061.It is shown that the results comply well with those available in the literature;this method can thus be used to evaluate the acoustic nonlinearity parameter of materials effectively.This technique can provide a practical way in the nondestructive characterization of degradation of materials and structures in the early fatigue life.
SHUI GuoshuangWANG YueshengJianmin QuJin-Yeon KimLaurence J. Jacobs
