Spectral Fatigue Analysis

Spectral fatigue analysis is an advanced numerical approach to determine the fatigue life of a ship structure under given environmental conditions to be encountered during its design life. The stress transfer function for various loading and heading conditions are computed with the help of the hydrodynamic and structural analysis tools which were later combined with given wave spectra and scatter diagram to derive the stress response spectrum. Finally, the fatigue damage is calculated using Palmgren-Miner’s rule, considering the appropriate S-N curves.

Boundary element based method capable of solving forward speed problem is generally used for sea-keeping analysis of ships. At IRS, an in-house developed software IRSPEED is used to perform the hydrodynamic analysis which is based on Green function theory and accounts forward speed effects to compute motions, loads, and pressure RAOs. The load transfer to structural model, post processing of structural analysis and spectral analysis is performed using an in-house developed tool.