Analysis And Calculations Of The Global Vibration Of A SWATH

Vibration phenomenon exists widely in the operation of marine vessels, the bad vibration may endanger the safety of the ship, and the prediction of the relative performance of the ship vibration is of great significance to a ship in the design stage.SWATH's rapid development has attracted more and more attentions. However, at the same time, its special ship type determines its vibration type complex, easy to produce coupling vibration. Vibration analysis about SWATH is much less compared to mono hull ship. Under this background, in this paper, the structure acoustic coupling method and the method based on the two-dimensional boundary element for the strip theory on a SWATH of research on the vibration characteristics of the ship, and the calculation results and the typical vibration of catamaran are summarized.First, this paper introduces the theory of the general vibration of ship, summarizes several main methods to calculate the natural frequency of the total vibration of the ship, and derives the boundary element method to calculate the velocity potential.Secondly, the paper introduces the main application of the coupled acoustic-structural method, introducing the principle of Lanczos calculation, the software analysis of the use of this article pre-post of processing.Furthermore, the vibration characteristics of a SWATH ship were analyzed with two kinds of calculation methods, including solving "dry" mode and "wet" mode of the inherent frequency and vibration type. According to the conclusion of the vibration mode, the SWATH can form a variety of special vibration modes due to the special structure and the water in the submerged body. The coupling of the submerged body and the main body increases the complexity of the vibration. By comparing the results of the two methods, it is proved that the singularity distribution method is accurate for the calculation of added mass.Finally, according to the actual demand of the project, the influence of welding quality on the ship vibration calculation is discussed. According to the size of the welding distance, the effect of spot welding is simulated by the way of releasing the node. The result shows that the welding quality (the position) of the welding quality has certain influence on the result of the vibration analysis of the ship.