Structural vibration transmission in ships using statistical energy analysis
This thesis presents the results of an investigation into the application of statistical
energy analysis (SEA) to predict structure-borne noise transmission in ship structures.
The first three chapters introduce the problems of noise and vibration in ships; the
previous research on the application of SEA to ships; the basic theory of SEA and the
experimental measurement techniques and procedures used to gather data
The main body of this thesis presents a wave transmission model for the hull frame joint
which is commonly encountered on the hull, bulkheads and deck plates of ship
structures. The wave model allows the transmission coefficients to be calculated for hull
frame joints which can be used in the coupling loss factor equations of SEA models.
The joint model has been verified against measured data taken on a simple two
subsystem single joint laboratory structures and a large complex 38 plate test structure
with multiple joints intended to represent a 1/10' scale model of a hull section. In
addition to the laboratory structures, the SEA modelling of sections of a ship is
presented for a large ribbed deck plate, a section of the ship superstructure and a section
of the ships hull. The results from the SEA models are compared with measured
attenuation data taken on the respective ship sections. A large amount of damping data
has been gathered on the test and ship structures and an equation for the internal steel
based on data gathered by other researchers has been verified.
It has been shown in this thesis that SEA can be applied to ships. Better agreement is
found with real structures in contrast to the poor results presented for SEA when applied
to simple one dimensional structures. The level of detail of the model is important as a
coarse model yields better predictions of vibration level. As with all models the results
are sensitive to the damping level and it is necessary to include bending, longitudinal
and transverse wave types in any SEA model to obtain the best prediction. It was also
found that the flange plates can be neglected from the frame joint model without
compromising the accuracy.