The power of ultrasonic spectroscopy in the complete characterisation of materials

In this report a process is presented which allows the complete characteris ation of homogeneous structures using ultrasonic spectroscopy. This analysi s makes use of only two backwall time domain signals of the media being tes ted Since they present an attenuation almost linearly proportional to frequ ency, the use of the Fast Fourier Transform and an adequate processing of t he echoes in the frequency domain have permitted one to evaluate the amplit ude and phase responses characterising the media. The amplitude response in conjunction with the respective linear function has allowed the measuring of the acoustic impedance and attenuation, and the phase spectra have permi tted the evaluation of the thickness and phase velocity. Such parameters ca n give a great contribution to the total characterisation of structures, na mely in terms of grain size and percentage porosity.