Passege of a bending wave through an inhomogeneity within an absolutely hard rib backing an elastic plate

The wave properties of the system consisting of elastic plate and absolutely rigid infinite rib with a deffect on a segment is examined. The two kinds of studied deffects are an elastic inclusion and a gap.
The Green function method is applied to the diffraction problem and transformes it to singular integro-differencial equations on an interval. For the case of short deffects the nonresonance and resonance asymptotics of scattering pattern are obtained. Bibliography: 5 titles.
These results show that the coefficient of penetration for the gap is much larger than that for the elastic inclusion if the frequency is non resonant.