Study On Added Mass Of Plate And Stiffened Plate

The influence of the added mass on local vibration has drawn more and more attentions from people in recent years. Calculation on plate and stiffened plate by using added mass method has great theoretical significance and practical value. Although the 3D fluid-structure coupling analysis method can accurately simulate the structure and fluid, the workload is vast and the cost of calculation is high. This paper adopt plate finite element model and 3D fluid finite element model which are coupled together to analyze the characteristics of plate and stiffened plate in the water, simplifying the calculation and taking into account the effect of fluid loading reasonably.Based on a series of the calculation and analysis on natural frequencies and modes of the rectangular plate and stiffened plate immersed in the water under simply supported and fastened conditions, this paper puts forward two methods to calculate vibration mode of plate immersed in water and stiffened plate. One of the methods is to introduce a dimensionless coefficient M, drawing additional water quality coefficient curve of vibration of plate and stiffened plate, using curve interpolation to obtain additional water quality coefficient, and then take it into the calculating formula offered by this paper, we can easily calculate the natural frequency of rectangular plate and stiffened plate. The model of the plate in water is considered to be similar with the model in air. Another method is to bring forward a formula for calculating additional water quality per area of plate immersed in water and stiffened plate, and then enter the result into the prepared program in order to calculate the natural frequency and mode of plate and stiffened plate in water quickly. Finally, we compare the result by using this paper's method with the one by using ANSYS coupling model and the result of trail.Added mass arithmetic mentioned in this paper can calculate not only the (1,1) mode of plate and stiffened plate in water but also calculate the (1,2) (2,1)mode.The former formula can only calculate the (1,1) mode. By calculating on the fluid-structure coupling local vibration of box type structure and engine room structure, showing that the method in this paper is feasible and has practical value and superiority.