基于改进型消灭曲线法的横摇阻尼估算

自由衰减试验仍是目前最为有效且常用的估算横摇阻尼系数的方法.横摇阻尼系数的估算精度对于船舶横摇运动的预报起着至关重要的作用.通常采用所谓的消灭曲线法来分析自由横摇衰减数据.该方法的一个不足之处在于其推导是基于忽略了非线性恢复力项的自由横摇运动方程.另一方面,考虑更多非线性成分的能量法能够纳入该因素影响但在实施过程中较为复杂.文中提出了一种改进型的消灭曲线法,能够纳入船体非线性恢复力项的影响.所提出的方法形式简单且相比能量法更易于实施.数值试验证明了改进型消灭曲线法的正确性,并展现了其相对传统消灭曲线法所具有的优势.

Enhanced Extinction Curve Method for Roll Damping Estimation

Accuracy of roll damping estimation plays a crucial role in ship roll motion predictions. Free-decay test is still so far one of the most useful and popular methods to estimate the roll damp-ing coefficients. The so-called extinction curve method is often used for analyzing the free roll decay data. One shortcoming of this method is that it is derived based on free roll motion equations neglect-ing nonlinear restoring terms. On the other hand, more sophisticated energy method can take into ac-count this nonlinearity but is relatively complicated to implement. In this paper, an enhanced ex-tinction curve method is proposed, which can take into account the nonlinear restoring terms of ship hulls. The proposed method is in a simple form and is easier to apply than energy method. Numeri-cal experiment proves the validity of the enhanced extinction curve method, and demonstrates its ad-vantages over conventional extinction curve method.