Towards the prediction of hullspringing response

Research on wave induced vibration in ocean going ships has been undergoing the revival during the recent years. The increased flexibility in hulls owes to increase in ship size, primarily the ship length. Springing vibration is induced by unsteady pressure field on the hull and it decays slowly due to low structural damping and the recursive wave excitation. Due to its large number of cycles springing vibration may represent a fatigue problem in different ship forms – e.g. full form ships in ballast condition, ultra large containerships, fast passenger ships. Springing was a subject to many theoretical and experimental investigations during the last decades. In order to become a part of the hull design practice and to be considered explicitly springing calculation procedure must be well defined with a reasonable CPU time and accuracy. In the present study results from two different strip theories have been compared for an example ship. Further, the hydrodynamic pressure solution obtained by the radiation-diffraction panel method program has been employed by a hydroelastic strip theory in order to obtain the vertical wave excitation force on the hull. The influence of the diffraction wave pressure on springing prediction has been analyzed.