| Scattering happens as soon as the ultrasonic wave runs into holes or inclusions defects in solids. The scattering waves contain all characeristic information of the defects. The scattering of flaws is more complicated than that of a isolated flaw, which cause the complication in aural detection. It is of fundamental importance to investigate the ultraonic wave-flaws interaction. A two-dimensional plane strain finite elment models with absorbing boundary conditon have been developed to investigate the ultrasonic wave propagation in multi-flawed isotropic media, with pairs of parallel and tilt cracks of different distribution relative to surface; pairs of cylindrical holes of kinds of distribution with pulsed-ultrasonic-plain-longditudinal/transverse-wave is investigated, decompsing the longitudinal and tranverse parts and subtracting the first scattering, clearly observe the multiple scattering and compare with experimental observations obtained by dynamic photoelasticity method.Then the research move onto the inclusion conditons, with an isolate inclusion and pairs of inclusion and companied the pulsed-ultrasonic-plain-compression-wave. Theoretically deduce reflection and refraction coefficient when incidence ultrasonic wave is from solid to solid and compare numerical coefficient of inclusions as Cast-iron, copper and steel. Solid with cylinder flaws of hypodispersion, Gaussian distribution and exponential distribution is investigated. The results are informed of a-scan plots and velocity plots, compared and investigate the alteration of velocity.
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