LAUSR

The difficulty of applying ultrasonic techniques to bi-material structures lies in the fact that different phenomena coexist, such as the non-linear effects caused by the adhesion properties between matrix-fibers and the diffraction effect caused by the periodicity of those structures. This work deals with the study of the combined effect of non-linear effects on a 3D bi-materials structure “polymer-titanium.” For this purpose, a Snapscan system is used which generates high amplitude pulses and receives signals composed of the fundamental mode and the higher harmonics. The transducers used are chosen according to the thickness and the periodicity scale of the sample. First, measurements in transmission are made where the transmitted ultrasonic waves are measured by changing the angle between the receiver and the sample. For each angle, a spectrogram is realized. The experimental observations on the spectrograms show that for small incident amplitudes we measure only the fundamental frequency. When the amp...