Chen D., Che C.

Though elastic interlayers may be effective for the attenuation of structure-borne sound in building structures, they are not practical for use in ship structures for the reason that such structures must be not only statically stable but also watertight. In the later case, rigid means such as blocking masses may be used to reduce the transmission of structure-borne sound. As the complexity of practical build-up structures will cause a lot of difficulty in theoretical analysis, a simple model of rigid corner at arbitrary angles, which consists of two infinitive plates, with blocking mass is considered here. Two local coordinate systems are introduced in this paper to analyze the transmission and reflection of vibration energy at such a corner. Firstly, general relations, which are written in matrix form, of the transmission and reflection coefficients taking account of the effects of nearfield at the corner with blocking mass are deduced by theoretical wave analysis. Then the transmission efficiencies and transmission loss for several kinds of corners, which consist of steel plates of different thickness ratio, angles etc., with blocking mass are computed. The results are compared with those of the same kind of corner without blocking mass to demonstrate the effect of blocking mass on structure-borne sound attenuation. Finally, computations for a certain corner with different kinds of blocking masses are performed so as to investigate the dependence of transmission efficiency on the parameters of blocking mass, which are of meaning to minimize structure-borne noise transmission in ship structures.