Experimental Study On The Effect Of Added Mass Caused By Internal Water On Hull Vibration

Hull vibration is always the field attracting people's attentions. Vibration can affect not only the ship structure, facilities and crew onboard but also the target of special mission ships. As we know, engine is one of the main vibration sources with low-frequency in the vertical direction. Therefore, our job focuses on the study of low natural frequency of ship structure.The issue that the internal water will make a great effect on the first order of natural frequency of hull vibration is raised. Based on experiments and numerical simulation, we studied the effect of internal water on the hull vibration mode. First of all, it introduces the background and meaning of subject making and the general situation as well as development of study in China and abroad. Then, it introduces corresponding knowledge and theory of modal experiment and added mass. After that, it makes detail explanation about the experiments in this paper. In the experiment, a ship model is used. It includes both strain experiment and modal experiment two parts. The purpose of the strain study is to find the elastic modulus of the ship model. It's important for the numerical study. Modal experiment consists of two parts. In part1, the ship model is hung in the air. In the other part, the model is put in the water tank. In these two parts, different weight of water has been added into all cabins. Meanwhile, ANSYS is used to do the numerical simulation. Finally, some conclusions are drawn from the comparison between experimental data and numerical results. Inner liquid of hull structure produces added mass, while reduces the first order of natural frequency of hull vibration. Therefore, it can't be ignored when doing numerical analysis.