Numerical Simulation And Full-Scale Testing Of Local Vibration On A Small-Sized Scientific Investigation Ship

Scientific investigation ships p lay an important role in the research of the ocean. And many countries in the world have taken the developments of scientific investigation ship as one of the important measures for the development of marine science. According to the requirements of study, scientific investigation ships may take a long time to sail in the ocean and perform a variety of different types of experiments in the marine laboratory. And also various types of measuring instruments and equipment are needed to carry. The vibration problems of the scientific investigation ships are particularly prominent, not only for the reason of the crew on the ship, but also for the instruments equipped. In this paper, the numerical model of local vibration of a small-sized scientific investigation ship is established by using MSC.PATRAN/NASTRAN software. At the same time, the full-scale vibration measuring instruments are employed to test the local vibration of the ship.Firstly, the natural frequencies of the scientific research ship are analyzed. The model of scientific investigation ship is established in software. The hull is simulated through the three-dimensional model of plate elements and beam elements. The corresponding parts of the ship's equipment and instruments are set by way of the point mass applied to the hull. The mass of attached water was calculated according to formula of the hull vibration rules of CCS. It is attached to outboard plates.Secondly, the forced vibration response of the ship hull is simulated. The excitation force, the damping and boundary conditions are determined before the calculation of the forced vibration response of the ship. According to the actual conditions, the results of the excitation force are applied to the model. The boundary conditions are simulated by spring elements. Through the transient response analysis of the model, the vibration acceleration, velocity and displacement of different nodes of the ship hull are calculated, respectively.And then, local vibration of the scientific research ship vibration is tested in real navigation. The measurement of the scientific investigation ship requires the results of vibration acceleration, vibration velocity and displacements on ship stern, the main deck and the superstructure. Then the result of experiment and numerical simulation of simulation data of the same sites are compared and analyzed.Finally, reduction measures of local vibration are analyzed. According to the results of the calculation of forced vibration and the measurement results of vibration experiment, the vibration of different sites is obtained by using the finite element analysis method. Different modification measures on the ship are compared, to reduce the vibration amplitude.