Abstract
The theoretical study for quantitative evaluation of material quality by the backscatter of an ultrasonic Gaussian beams has been made. The density and location of flaws, such as microcracks and porosities, can be estimated by the change of electrical power due to the backscatter. The power change is theoretically formulated based on the dynamic reciprocal theorem. Some kinematical postulations are used for simplicity to neglect the multiple scattering effect among the flaws; the characteristic dimension of a contained flaw is very small in comparison to the incident wavelength, and the flaw distribution is sparse. Numerical calculations of the analytical backs-cattering power have been carried out. The power is approximately proportional to the flaw density. The obtained expression is of closed form, and it is easy to calculate the power. Thus, the expression is practical for the quantitative characterization from the backscattering wave data by ultrasonic measurement.
