A model for determining electromechanical response profile of ultrasonic transducers and ultrasonic transient echo

Models for calculating the radiation, scattering and reception of ultrasound are developed to provide a good understanding of the physical essence of ultrasonic testing. The process of ultrasonic wave generating by pulse, propagation in the medium and received by the transducer is analyzed, and the received ultrasonic signal can be found by convolving of the electromechanical response of transducer with the flaw impulse response. A model is proposed to predict the echo response from a defect of complex geometry based on the Huygens' principle of superposition. Spatial impulse response and Kirchhoff approximation are applied to model the interaction of the ultrasonic wave with flaws. The electromechanical response profile of transducer is calculated by deconvolution the echo of plane test block with impulse response of the test block. Characteristics of flaw impulse response of targets on and off-axis are analyzed in detail, the received ultrasonic echo is explained in terms of the plane and edge echoes, however, polarity is opposite. The amplitude of the direct echo is far greater than the edge echo. The theoretically predicted results are in good agreement with the experimentally results.