研究了船舶随浪中大幅参数激励随机非线性横摇运动的计算方法,将船舶稳性高度↑_GM作为时变的随机参数激励,建立了船舶随机随浪航行情况的参数激励横摇运动微分方程,方程中的三次阻尼项根据自由横摇船模实验数据求出.参数激励项的求解考虑了船体纵摇、升沉及波浪运动对稳性高度变化的影响.在有义波高分别为10m和12m的2种不同随机波作用下,考虑初始横摇角为3°以及定常风作用下发生5°永倾角,计算出随机参数激励下船舶的时域横摇运动响应.计算结果表明此方法可以用于计算随机随浪中船舶的参数激励横摇运动,同时显示了随机随浪对船舶横摇和倾覆的重要影响.
A method was developed to calculate ship's roll motion due to parametrical excitation. The differential equation of ship's parametrically excited roll motion was established considering the metacentric height ↑_GM-variation, which was regarded as a random parametrical excitation. The linear-plus-cubic damping model was calculated according to the data of free-decay experiment. The random parametrical excita- tion was calculated including the pitch, heave and motions of the longitudinal waves. The responses of roll motion were obtained for the ship in irregular longitudinal waves of 10m and 12m significant wave heights with respect to the initial roll angle of 3°and the bias heel angle of 5°which was assumed to be caused by the permanent wind pressure. The result indicates that this approximation can be used to calculate the ship's roll motion due to parametrical excitation, and reveals the important effect of the random following wave on the ship rolling and capsizing.