REDUCTION OF HULL WHIPPING IN SLAMMING BY ACTIVE CONTROL-SYSTEM

The reduction of hull girder whipping in slamming by an active control system is investigated. Under the consideration of hull flexibility, a mathematical formulation is developed for the whipping of a hull, su bject to slamming, and including an active vibration control system co nsisting of a tuned mass and hydraulic servo system. Using the optimal theory, the control law of the active system is determined. In additi on, a closed-loop estimator is introduced to estimate the distribution of hull motion, which is required to compute the actuator output of t he active system. Finally, a numerical example of an application to a 205-ton high-speed craft is described. The results show that the whipp ing will be reduced significantly. The whipping acceleration and induc ed stress in particular are reduced more than 95% within 2 sec by this scheme.