船舶横摇非线性阻尼系数识别

根据自由横摇曲线估算船舶横摇非线性阻尼系数,用于预报船舶海浪中的运动．提出了能量衰减函数的概念,并由实际能量衰减函数与估算能量衰减函数之间的方差最小来确定非线性阻尼系数．由船模的自由横摇试验曲线,分别估算了平方阻尼模型及立方阻尼模型的非线性阻尼系数,并与试验数据进行了比较.结果表明,在考虑了试验测量误差的情况之下,计算结果同试验结果很接近,可用于预报实船非线性横摇运动．该方法不需要事先确定阻尼的准确形式,并且可以满足大角度横摇回复力矩强非线性的要求．

Identification for Nonlinear Ship Roll Damping Coefficients

The identification method for nonlinear ship roll damping coeffcients is investigated based on the free-decay roll experiment curves to predict the motion of ship in the sea. The concept of roll energy decay function is put forward, and the nonlinear damping coefficients are solved based on the minor error between actual energy function and evaluated energy function. The damping coefficients for linear-plus-quadratic damping model and linear-plus-cubic model are calculated. The results are compared with the experimental data, indicating that the simulated rolling curve is close to the experiment rolling curve. This approach can be employed for the prediction of nonlinear roll motion of real ship. The damping model is not required in the method. The strong nonlinearity in the restoring moment is properly considered for large amplitude roll.