Thesis defence G.K. Kapsenberg: ships

14 June 2018 12:30 - Location: Aula, TU Delft - By: webredactie

On slamming of ships. Development of an approximate slamming prediction method. Promotor: Prof.dr.ir. R.H.M. Huijsmans (3mE).

Slamming of ships is a phenomenon characterized by a high wave load of short duration. These short duration loads can be generated by large amplitude motions, when a part of the fore body of the ship emerges from the water and experiences an impulsive load upon re-entry. Impulsive loads can also be generated by very steep waves that impact against the hull.

Usually the ships structure responds in a vibratory manner on this load. This vibratory response increases the extreme load and also the number of load cycles relevant for fatigue damage. Slamming is also known to be a major reason for operators to change course and/or reduce speed, therefore there is a large effect on the economy of a ship. These aspects are the motivation for carrying out this study.

The objective of this thesis is to develop an approximate and fast method to calculate slamming loads. This method can be included in a simulation program for ship motions and loads in waves. In this way long duration simulations can be made and worst cases can be selected. The selected cases can then be studied in detail by either CFD methods or experiments using a model of the ship.

The approximate method is based on momentum theory; it uses the amount of fluid that moves with the ship and how this amount, the added mass, changes in time. It appeared that the effect of the bow wave developed by the forward speed of the vessel and the pile-up of water when the ship immerses are important components to properly calculate the impulsive loads.

Results of the simulations have been validated against results of experiments with a scaled model of a ship in a wave basin. Forces have been measured on segments in the bow of the vessel and have been compared to calculated values. The results are not perfect, but are considered useful for the intended purpose.

More information?

For access to theses by the PhD students you can have a look in TU Delft Repository, the digital storage of publications of TU Delft. Theses will be available within a few weeks after the actual thesis defence.