MODELING OF IMMERSION ULTRASONIC TESTING AND SIMULATION OF SCATTERED WAVES BY FLAWS

摘要

This paper proposes a mathematical model based on a linear time-shift invariant (LTI) system for nondestructive ultrasonic testing (UT). We consider here an entire model of the immersion UT including ultrasonic wave generation in water, transmission from water to solid and vice versa, and scattering by flaws in the solid. A multi-Gaussian beam model is introduced to express wave propagation in both transmission and reception processes. The scattering process is calculated by means of boundary element method. These processes are expressed by frequency dependent modules in the LTI system, and the total output signal is obtained as a product of the modules. The performance of this model is shown by numerical simulations of flaw-echoes from internal and surface-breaking cracks.