100


Functionalities to calculate internal loads and handle structural meshes were added to the hydrodynamic solver FATIMA. Initially this program only calculated ship motions and added resistance in waves. FATIMA uses RAPID as a pre-processor to calculate the steady wave profile around the ship due to forward speed. And because extra func- tionalities were built in, a 3D FE model was used to validate the hydrodynamic response and stresses. Results of simulations were compared to experimental results from model tests and also from a full-scale monitoring campaign.


The knowledge gained within this project, and other projects, has led to structural coupling methods for other hydrodynamic solvers as well. PRECAL_R already offered the same possibilities through the develop- ment of the STRUC_R software in the Cooperative Research Ships (CRS) program. DIFFRAC can be used too when it concerns more complex ship hulls or in combination with mooring configurations.


10 20 30 40 50 60 70 80 90


0 structural lifetime Impact of winter and all year round operations on accumulated fatigue damage with respect to different routes


Fatigue calculations with SAFETRANS The stress transfer functions calculated with the structural coupling tools can be used to predict accumulated fatigue damage for the lifetime of a vessel or per operation. Using SAFETRANS, this was done in a study for an operator in which two different transport routes were investigated. The MARIN software SAFETRANS facilitates voyage simulations. For instance, hydrody- namic response, the likely decisions of the captain and seasonal environmental conditions can be combined to result in a realistic voyage simulation of a ship sailing between


two ports. Typical results are statistics concerning voyage duration, motions and fuel consumption.


Material fatigue damage is accumulated in the structure through continuous cyclic loading of the ship hull. The amount and amplitude of these load cycles are important parameters in the fatigue life consumption. Sailing in heavy environmental conditions will have a significantly larger impact on the structure’s fatigue damage than calm weather. The relationship between hydrodynamic load and structural stress was input into SAFETRANS. The outcome of the study showed the differences in accumulated fatigue between winter time and year round activities. The effect of the chosen transport route on vessel lifetime was also clearly observed. Operating along the second route would result in twice as much fatigue damage, when compared to the first route.


In the last couple of years, the capabilities of the hydro-structural coupling tools have made a significant step forward. Facilitating the link between hydrodynamic loading and structural response offers possibilities to assess a ship’s structural lifetime in the design stage, as well as during operations. Developments are constantly being made, as interest for these tools and their applications increases.


report 11


Route #1, Winter Route #2, Winter


Route #1, Summer and Winter Route #2, Summer and Winter


remaining fatigue budget []


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