A Numerical Investigation on Nonparametric Identification of Nonlinear Roll Damping Moment of a Ship from Transient Response

This paper is concerned with the determination of nonlinear roll damping moments of ships including similar floating structures. Using the measured motion response data of ship's roll motion, an inverse problem is formulated for the determination. The problem of damping determination is mathematically involved in a Volterra integral equation of the "first" kind between the roll responses and unknown nonlinear roll damping. This first kind integral equation results in numerical instability, that is, solutions lack stability property. A regularization method is applied in order to suppress the instability. Any priori information is not required on the model of the nonlinear damping. The applicability of the present study is demonstrated through the numerical investigations using the given nonlinear roll equations from the tests.