双壳结构频散特性及聚能效应分析

Frequency dispersion characteristics and cumulative effect of double cylindrical shells

以浸没在流场中的双层圆柱壳为研究对象,分析了静水压力、不同边界条件对其频散特性的影响规律。在典型壳体结构多模式频散特性分析基础上,探索双壳结构复杂激励下的能量聚集现象,初步给出了壳体能量聚集判据。结果表明:壳体4.5 MPa静压下增大了壳体高阶周向模态下低阶波的传播速度。壳体边界条件对低阶周向模态对应的无量纲振动频率影响较为显著。壳体聚能效应在低阶周向模态下较为显著;随着周向模态数增加,结构声的能量聚集现象逐渐向高频移动。

This paper considers the underwater double cylindrical shell as the main subject, and discusses the influences of hydrostatic pressure and boundary conditions on its frequency dispersion characteristics. Based on analyses of the multimode dispersion characteristics of typical hull structure,the cumulative effect of complex double shell structure is explored in order to provide the criterion of the energy cumulation. The results show that the wave propagation velocity under higher order circumferential mode of the hull is increased under 4.5 MPa ultimate hydrostatic pressure and the non-dimensional vibration frequencies under lower order circumferential mode are significantly affected by the hull boundary conditions. It also shows that the cumulative effect of typical hull structures is obvious under lower order circumferential mode, and the acoustic cumulative effect of the hull structure moves towards high frequencies with the increment of circumferential mode.