水下环肋圆柱壳弹性失稳临界载荷无损预报方法

基于振动的水下环肋圆柱壳临界载荷的预报具有结构无损的优势。以Flügge壳体理论和基于正交各向异性理论的环肋圆柱壳自由振动方程为基础,运用波传播法得出耦合系统的频率方程,并求出对应外压下的固有频率,通过最小二乘法线性拟合获得临界载荷、外压及固有频率的关系表达式。绘图得知任意边界的同一模态下,水下环肋圆柱壳的固有频率平方与静水压力成正比。结构失稳时,刚度丧失,固有频率降为零,据此求出水下环肋圆柱壳的最小弹性临界载荷。分析了不同边界条件对环肋圆柱壳临界载荷的影响,得知边界约束越强,环肋圆柱壳的临界载荷越大。结果对比表明了本方法的正确性,为水下环肋圆柱壳的固有频率及临界载荷的理论计算提供了一种新的方法。

Elastic critical pressure prediction of submerged ring-stiffened cylindrical shell based on frequency characteristics analysis

The critical buckling load of a submerged ring-stiffened cylindrical shell is nondestructively predicted based on a new analytical method. According to Flügge theory and orthotropic theory, the sound-structure coupling equations of this system are established considering the effect of ring ribs and hydrostatic pressure. By solving these equations, data of the natural frequencies of this system are obtained under different pressures. Subsequently, the relationship between the natural frequency squared and the hydrostatic pressure can be obtained. And then a curve in which the abscissa axis represents the pressure and the ordinate axis represents the frequency squared, can be drawn by using the data, which turns out to be a straight line approximately. Finally, the critical pressure is obtained at the corresponding point according to the curve. Besides, the effect of various boundaries on the ring-stiffened cylindrical shell is additionally studied in this paper. The results agree well with previous references.