环肋椭圆柱壳-流场耦合系统自由振动的解析求解方法

Analytical method of free vibration characteristics of ring-stiffened elliptic cylindrical shell-fluid coupling system

提出了分析环肋椭圆柱壳-流场耦合系统自由振动的一种解析求解方法。环肋通过"刚度均摊"到均质椭圆柱壳体上,考虑流场对壳体振动特性的影响,通过Helmholtz方程描述声介质的波动,建立环肋椭圆柱壳-流场耦合系统的自由振动方程,进而求得耦合系统的自由振动固有频率。为了验证方法的准确性,将水下环肋椭圆柱壳退化成水下环肋圆柱壳和不加肋的水下椭圆柱光壳,两个退化模型的计算结果与已有文献结果吻合良好。并详细讨论了椭圆度、环肋间距等主要参数对耦合系统自由振动特性的影响。

A theoretical method to solve the free vibration characteristics of ring-stiffened elliptic cylindrical shell-fluid coupling system is proposed. The effects of ring stiffeners are evaluated based on “ smeared” stiffener theory whereby the properties of the stiffeners are averaged over the shell surface. Taking the effect of flow field on the vibration of the shell into account, the f lu id sound pressure is described by the Helmholtz equation,and the free vibration equation of the coupling system is established,and the natural frequency of the coupling system is obtained. To verify the accuracy of the present method,the submerged ring-stiffened elliptic cylindrical shell is degenerated into two models, one of which is a submerged ring-stiffened circular cyl indr ical shell and the other of which is a submerged elliptic cylindrical shell without ring stiffeners. The present results of the two degenerated shells show good agreements with available results from literature. The influences of the main parameters of the shell and ring stiffeners on the vibration characteristics, such as ellipticity parameter, stiffeners interval ratio and size of the stiffeners, are also discussed in detail.