基于稳定性理论的张力腿平台横摇固有周期分析

文章以稳定性理论为基础提出了一种张力腿平台横摇固有周期计算模型,分析了横摇临界角对平台横摇稳定性的影响,并将其应用于分析平台设计参数对横摇固有周期的影响。提出在一个横摇周期里,最后稳定横摇临界角对应的时间历程为1/4横摇固有周期这一假设,基于此假设,编制计算机计算程序,计算横摇运动中每一个横摇角,判断其稳定性,找出一个横摇周期内最后稳定横摇临界角对应的时间历程,求解横摇运动固有周期。考虑两种横摇阻尼情况,计算不同初始横摇角、横摇下沉位移、张力腱长度、平台重量和横摇阻尼的横摇固有周期,论证了平台设计参数对横摇固有周期的影响。该计算模型克服了从结构角度计算固有周期工作量大、计算周期长、计算结果不可靠的弱点,使横摇固有周期计算简单、有效。通过与不考虑横摇阻尼的情况对比,分析了横摇阻尼对横摇固有周期的影响。可以快速计算处于设计阶段或者已服役张力腿平台横摇固有周期。结合一型设计中的张力腿平台,应用文中提出的横摇固有周期计算模型对该平台进行了横摇固有周期的计算,并且分析了平台参数对横摇固有周期的影响。结果表明该方法可以对张力腿平台横摇固有周期进行快速计算。并可推广应用于其它海上结构物的横摇固有周期计算。

Analysis rolling natural period for tension leg platform based on stability theory

A calculation model was established to research on rolling natural period of Tension Leg Platform (TLP) based on stability theory. The effects of roll critical points on rolling stability and effects of parame-ters of TLP on rolling natural period were analyzed. And an assumption was put forward that in one rolling motion, times courses corresponding the last stable roll critical point condition is a 1/4 cycle process. Based on the assumption, computer programs were built to calculate arbitrary roll angle, and used to estimate sta-bility of arbitrary roll angles, so that times courses corresponding the last stable roll critical point in one rolling motion were found. So it can obtain rolling natural period. Considering two conditions of damping, this paper calculated rolling natural period under different initial roll angle, displacement of roll subsidence, length of tendon, weight and roll damping coefficient and demonstrated the influences of parameters of TLP on rolling natural period. The model is simple and effective to support fast estimating rolling natural period whether TLP is in designed stage or in service and avoid to obtain rolling natural period complicated with structural theory. The influences of roll damping on rolling natural period were demonstrated. Based on a TLP which is in design stage, the rolling natural period was obtained with the established model. In this case, the influence of parameters of TLP on rolling natural period was found. Results show that the model is simple and effective to support fast estimating rolling natural period. This model can also apply to oth-er marine structures to calculate rolling natural period.