Class notation using direct load calculation for the evaluation of fatigue, yield and buckling within the cargo area.

Purpose

To calculate the strength of the hull structure within the cargo area by using directly calculated hydrodynamic loads. Both fatigue and ultimate strength (yield and buckling) are evaluated.

Wave loads are calculated in a hydrodynamic program and transferred to a structural model of the entire ship.

Benefits

A CSA-2 ship has a higher fatigue life for critical details than a normal classed ship. It will therefore be a safer ship, with less likelighood of fatigue cracks. The increased fatigue strength will lead to pollution and ship repairs being less portable thus reducing the long-term cost for the owner

Features

The notation applies direct calculations of the wave loads and finite element calculations of the total hull extended fatigue and buckling control, as well as of the ultimate hull girder strength control.

The design load conditions are to include the ballast, full load and part load conditions based on the load definitions for direct strength calculations.

In connection with the direct wave load calculations, it is important to observe that the comparable wave loads are based on a rational combination of characteristic hull parameters, backed by long experience and checked by non-linear wave load calculations. The rule wave loads correspond to a maximum wave response at 10-8 probability in the North Atlantic. The effect of forward speed is included in the analyses.

Stochastic (spectra) fatigue analysis is performed for longitudinals/plating and other critical locations within the cargo hold area. The Ultimate strength is analysed based on linear and non-linear wave loads.