海洋顺应式结构的非线性动力响应分析

ANALYSIS OF NONLINEAR DYNAMIC BEHAVIORS OF A COMPLIANT STRUCTURE

将海洋平台中顺应式结构简化为底端具有线弹性扭转弹簧约束，顶端附有集中质量块的水中柔性梁。采用连续介质力学方法，应用大挠度理论建立了梁的非线性耦合运动控制方程和边界条件。应用Morison方程给出了流体力的表达式。运用有限差分法和Runge—Kutta法得到了方程数值解。分析了梁在各种激励下的非线性振动特性，以及拖拽系数对梁振动的影响，并对大挠度理论下非线性梁与横截面转角近似下非线性梁及线性梁三种梁的振动响应进行了比较。

A compliant structure in the ocean environment is modeled as a beam supported by a linear-elastic torsional spring at the base and attached a mass point at the free end. Using the method of continuum mechanics and on the basis of large deflections, the nonlinearly coupled equations of motion and boundary conditions are derived. The fluid forces are modeled using a semi-empirical Morison equation. The forced vibrations are analyzed through the finite difference approach and Runge-Kutta method. The influences of drag coefficients on the vibrations are studied. The comparison between the results of the nonlinear structures both with an accurate angle and an approximate angle and that of a linear structure are also made.