基于共振转换器的自主水下航行器动力学建模及减振降噪
DYNAMIC MODELING AND VIBRATION AND NOISE REDUCTION OF AUTONOMOUS UNDERWATER VEHICLES BASED ON RESONANCE CHANGER
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摘要: 文章以自主水下航行器(AUV)振动噪声抑制及其隐秘性提高为研究背景, 提出了一种含有轴承非线性的AUV振动−声学模型, 并通过寻找共振转换器(RC)最佳设计参数使壳体产生的振动声辐射功率级最小, 达到反共振的目的. 首先通过Lagrange法建立了含有浆−轴−壳的双梁系统有限元模型, 基于赫兹接触理论加入轴承非线性因素, 然后根据声传播原理推出了声偶极子辐射场模型; 然后, 采用Runge-Kutta法求解了系统振动响应, 通过时域响应、频谱、分岔和幅频响应图等后处理信号分析了系统的动力学特征; 最后, 以壳体声功率级作为代价函数并根据响应分析结果, 对RC进行参数设计. 通过对比非线性轴承和线性弹簧两种支撑, 发现AUV在非线性轴承支撑下壳体振动辐射声功率级主体趋势是沿着线性结果分布的, 同时均高于线性弹簧支撑下的系统噪声, 并且在对应共振区域达到峰值; 同时结果显示RC装置能够大幅度降低系统共振响应幅值及振动辐射声功率级, 尤其在共振频率设计点处减振降噪效果最为显著, 在共振频率设计点处频率没有发生偏移, 但在其他个别区间内, 除了最大共振幅值降低明显之外, 共振频率产生一定的偏移. 文章的理论模型揭示了AUV动力学响应特征及参数影响规律, 其研究结果可为AUV减振降噪优化设计提供新的改进思路, 具有一定的理论指导意义.Abstract: In this paper, the vibration-acoustic model of the autonomous underwater vehicle (AUV) with nonlinear bearings is proposed based on the research background of vibration noise suppression and its concealment improvement. By finding the optimal design parameters of resonance changer (RC), the vibration and sound power level generated by the shell is minimized to achieve the purpose of anti-resonance. Firstly, the FEM of double-beam system with propeller-shaft-shell by Lagrange method is established. The nonlinear factors of bearing based on Hertz contact theory are added, and then the acoustic dipole radiation field model is derived according to the principle of sound propagation. Secondly, the Runge-Kutta method is used. The dynamic characteristics are analyzed by post-processing signals such as time domain response, spectrum, bifurcation diagram and amplitude-frequency response. Finally, the shell sound power level as the cost function is used and the parameters of the RC are designed. By comparing the two supports of nonlinear bearing and linear spring, it is found that the main trend of the sound power level of AUV shell under the former is distributed along the linear spring, which is lower, and reaches the peak in the corresponding resonance region. In addition, the results show that the RC can greatly reduce the resonance response amplitude and sound power level, noteworthily, the effect is the most significant at the resonance frequency design point. The frequency at the resonance frequency design point does not be shifted, however, the resonance frequency has a certain offset in other individual intervals in addition to reduction of the maximum resonance amplitude value. The theoretical model of this paper reveals the dynamic response characteristics of AUV and the influence law of parameters. The research results can provide new improvement ideas for the optimization design of vibration and noise reduction of AUV, and have certain theoretical guiding significance.