A time-domain analytical method of one-dimensional wave propagating through underwater multilayer mediums
JIN Ze-yu, YIN Cai-yu, CHEN Yong, HUANG Xiu-chang，HUA Hong-xing
1.Institute of Vibration, Shock and Noise, Shanghai Jiao Tong University, Shanghai 200240, China;2.State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong University, Shanghai 200240, China
Abstract：The underwater pressure wave will generate a series of complex reflection and transmission waves when it spreads between the coating and the steel plate which would influence the input pressure wave. A time-domain analytical method to calculate the pressure of the wetted surface (the interface of water and coating) is developed based on the wave theory. The method can take all complicated reflections and transmissions into account and obtain the analytical solution. For the exponential decay wave input, comparisons between the analytical results and FEM results indicate the correctness of the method. At the same time, the results are also compared with the approximate results whose effects merely counted once or twice reflection and transmission for the exponential decay wave input. Through the comparison, the results are highly consistent with the approximate results for the rigid boundary, but obtain large error for the air-back and the water-back boundary. Furthermore, dimensional analysis for exponential decay wave is done to study the influence of the coating parameters to the results. The results of the analysis indicate that the peak pressure will decrease first, then increase and again decrease with the decreasing of the coating characteristic impedance. Besides, the peak pressure will decrease as the thickness of the coating increases or the input wave decay speed increases. The method is still applicable for q-layers (q≥3)medium.
2014, Vol. 33 
