Prediction of structure-borne sound transmission in large welded ship structures using statistical energy analysis

An efficient method is presented for the prediction of structure-borne sound transmission in large welded ship structures.
SEA (Statistical Energy Analysis) is used, and the equations used for the SEA parameters are also presented. Traditionally, the SEA method requires a great deal of work when steel structures are modelled. It is almost impossible to prepare models manually for large structures such as ships. In the method developed, the preprocessing programs used in the context of the finite element method (FEM) are applied to reduce the modelling work.
To date, one-dimensional beam, two-dimensional triangular and quadrilateral plate, and three-dimensional volume elements have been implemented. The assemblage of the loss factor matrix is made in a manner analogous to the stiffness matrix in FEM. In the computer implementation of the SEA program, standard FEM techniques are used to reduce calculation time, including the skyline matrix technique andLDLT-matrix decomposition of the loss factor matrix.
The effectiveness of the present method is illustrated by the computer run of the model of the passenger cruise vessel, which contained over 5000 elements and 17 000 coupling branches. It took only 17 min in the Iris Indigo R4000 workstation.
Application calculations for an echo sweeping vessel, a timber-container carrier, and a passenger cruise vessel are discussed, and comparison is made with full scale measurements.