海洋悬空管道非线性振动稳定性分析

以海洋悬空管线为研究对象，根据海洋悬空管道的主要特征，将海洋悬空管道简化为两端简支梁力学模型．涡激升力简化为简谐荷载。在考虑管道非线性因素下，建立悬空管道的横向振动方程，并采用谐波平衡法对方程求解。可得出洋流涡激作用下海洋悬空管道横向振动失稳的双尖点突变模型，由此导出悬空管道失稳条件。根据失稳条件分析发现．海洋悬空管长度对稳定性影响起主导作用，并在假定其他条件不变的情况下，分析影响悬空管道稳定性的因素和悬空段临界长度之间的关系。分析结果表明：随着外流流速、管内流流速、管内压强的增加，悬空管道的临界长度减小：随着材料弹性模量、管外直径的增大．悬空段的临界长度增加：其他影响因素相比较而言可以忽略．

Analysis on Stability of Span Submarine Pipeline Nonlinerity Vibration

Focuses on the free span of submarine pipelines. According to the free span of submarine pipeline＇s characteristic, it had simplified the free span of submarine pipeline as a beam simply supported at both ends, and the vortex lift mechanism as tune load at the same time. Taking account to the nonlinear factor, the dynamic equation was set up. Using the harmonic balance method to solve the equation, at last the two scrip catastrophe model of the free span of submarine under the excited vortex inducing vibration with the current effect was obtained. Through which the unsteady criterion of free span of submarine pipeline is obtained. It had been found that the length of the free span of submarine pipeline lies in the main position by analyzing the unsteady criterion. And then supposing other conditions without changing, the analysis on the relationship between the factors which will effect the span submarine pipeline＇s stability and the criterion span length is given. It can be found from the analysis that the critical span length decrease with the outer fluid flow velocity,internal fluid flow velocity and internal flow pressures＇ increasing. Contrasted to the factors have been analyzed above, the factors such as the water＇s density, the fluid damping and so on can be ignored with the increasing of elastic modulus, the external diameter of pipe and critical length in the span section.