Abstract:The singularity of the fluid stiffness matrix in the equations of motion was pointed out, which made the existing wet mode method unavailable. Meanwhile, the contradiction of the method that isolating the zero-frequency item was indicated. The paper shows that the root of the problem of the wet mode method is the unreasonable presumption that simultaneously neglects the compressibility of the fluid as well as the influence of the free surface fluctuation which aims at the easier computation. Two solutions called the direct method and the fixed point method are put forward based on the above conclusion. The direct method is more suitable for the computation with a small fluid domain scale while the fixed point method is fit for a large one. In this paper, the structural characteristics of an oil pan with different oil mass were calculated by a Matlab program based on the fixed point method. The comparison demonstrates that the structural modal frequencies decrease firstly, then increase and finally become flat with the oil mass increased increasing from 0. The deformation magnitude of the modal shapes decrease considerably when the fluid is added. For the same order of mode, the wet modal shapes differ a lot from the dry modal shapes with less fluid addition except the 1st mode. But the wet modal shapes tend to be stable and the same as the dry modal shapes with the continuous increase of the oil mass.
刘瑞骏,郝志勇,郑旭,谈江林. 改进的湿模态法在流固耦合中的应用[J]. 振动与冲击, 2017, 36(22): 199-204.
LIU Rui-jun, HAO Zhi-yong, ZHENG Xu, TAN Jiang-lin. The application of improved wet mode method in the fluid-structure interaction. JOURNAL OF VIBRATION AND SHOCK, 2017, 36(22): 199-204.
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