Numerical Prediction and Experimental Validation of Slamming Load for Large Container Ship Undergoing Parametric Rolling Motion

Abstract

This article proposes an approximate prediction method for slamming loads in parametric rolling condition for large container ships and the method has been validated through model experiments. Up to now, there have been some studies focused on two-dimensional asymmetric slamming analysis. Nevertheless, slamming load prediction in parametric rolling condition should consider not only heave and pitch motions, but also large amplitude roll motion which is usually neglected in analysis. For this purpose, a 6-DOF weakly nonlinear time domain model is adopted to predict the ship motions including parametric roll motion. The consequent roll motions obtained by the proposed model are incorporated in the calculation of impact angle and relative vertical velocity between ship section on the bow flare and wave surface, according to an asymmetric water entry assumption. Slamming impact loads and occurrence probability of slamming are analyzed by the Wagner model. To validate the numerical method, the segmented model experiment of a 10000 TEU container ship was executed and the slamming impact pressures and bending moments were measured for the wave condition and ship forward speed. The calculated pressures are compared with experiments. Based on numerical simulations, the maximum flare slamming pressures and slamming occurrence probability in different speed and wave conditions are investigated. The results indicate that flare slamming pressure is smaller than bottom slamming, but possessing longer lasting time and the occurrence of flare slamming is associated with the cycles of parametric rolling motions. Furthermore, the relationship between slamming pressure and 3-DOF motions namely roll, pitch and heave in the simultaneous simulation is given and the mechanism of flare slamming phenomena in parametric rolling condition is elaborated.