ANALYSIS AND INTERPRETATION OF RF SIGNALS IN ULTRASONIC

Abstract

Numerical simulation of ultrasonic waves is a powerful method for detecting changes in the properties of a solid medium. Changes in material properties, such as the formation of voids, cracks and density variations cause changes in the reflection, attenuation and velocity of the ultrasonic waves. These changes in the properties of ultrasonic waves are used to predict the size and location of the flaws in the solids. In this work ultrasonic beam of desired central frequency is modeled using its wave equations and then effects of cylindrical defects on the propagation of the ultrasonic waves are measured. The relation between distance of the . reflector (flaw) from the transmitter, size of the flaw and the sound pressure received by the piezoelectric receiver are represented by DGS diagram. Attenuation and dispersion of ultrasonic waves in AL block and Carbon steel wedge are calculated using experimental A-scan data. The variation of attenuation and velocity of the ultrasonic waves with its frequency is calculated using Short time Fourier transform (STFT). Scattering of ultrasonic waves in solid medium is calculated for different incident angles and plotted verses product of wave number and radius of the cylindrical block. Experiments are done on A-scan echograph and digital oscilloscope with an ultrasonic transducer of 5 MHz central frequency.