First-Order Response Effect on Second-OrderDamping of Mooring Line? ?
FAN Ju, CHEN Xiao-hong, HUANG Xiang-lu(Shanghai Jiao Tong University, Shanghai 200030,China)
In this paper we investigated the effect of first-order responses of mooring line on the second-order mooring line damping. In the analysis of the slow oscillation of a moored floating structure by the perturbation method in frequency domain,the second-order equations of mooring line are divided into non-homogeneous and homogeneous equations.The solutions are related to first-order responses of mooring line and second-order floating structure oscillation,respectively. In order to find the effect of first-order responses of mooring line,the second order mooring line tension and damping were determined by solving the non-homogeneous and homogeneous equations.From the results,it can be found that,although the second-order tension of mooring line obtained from the non-homogeneous equation is quite small compared with the total second-order mooring line tension,the damping contributed from both of the them are in the same order in quantity. So, in predicting the second-order mooring line damping, the effect of thesolution related to the non-homogeneous equation can not be neglected.