Dynamic loads: Slamming and Sloshing

Slamming

MARINTEK has developed a new experimental method to predict stern and bow flare slamming induced slamming loads. A segmented model with correct hydroelastic property has been used in the model test. Two different tests have been developed, namely comfort and whipping tests.

Comfort-tests to assess stern slamming induced vibration in moderate stern-sea
Whipping-tests to assess whipping induced global loads in extreme sea conditions.
MARINTEK has tested more than 70 different geometries of cruise, container and other ships in the last three years. We have also developed a method to design optimal stern and bow geometry in order to reduced slamming loads. The picture shows a model with a frame inside before one cuts the model.

Sloshing

Sloshing analyses are carried out at MARINTEK by use of sloshing software made in close co-operation with NTNU. The core of the program is an analytically based multi-modal approach that is robust and fast, so that long time simulations are possible. A 2-D sloshing simulation of irregular motions of a tank in a 3 hrs full-scale sea-state takes about 5 minutes on a modern PC. A 3-D extension of the multi-modal method has been developed at NTNU and is currently undergoing validation. The sloshing software has been successfully applied in several projects.

Model tests are necessary to accurately determine sloshing loads. At MARINTEK, a new laboratory has been equipped with a planar motion mechanism that facilitates forced motion tests of tank models in six degrees of freedom. An advanced steering system ensures precise regular or irregular motions.

An important part of model test studies is the scaling of measured loads to full-scale. MARINTEK has extensive experience related to scaling problems.

Contact person: Rong Zhao