Fatigue design of welded plates and shells for wave fatigue loading. Avoid local structural failure due to repeated environmental loads.

Stress cycle variations, causing reduced life expectancy, occur in all floating structures when subjected to environmental loads. Stofat is the postprocessor for fatigue design of welded plates and shells subjected to wave loading using a stochastic approach.

Stofat performs stochastic fatigue analysis on structures modelled by shell and solid elements and assesses whether the structure is likely to suffer fatigue failure due to the action of repeated loading. The stresses are typically due to hydrodynamic pressure loading acting on the structure. Finite element analysis in the frequency domain produces element stress transfer functions that are read into Stofat and used in calculation of fatigue damage.

The loads must be computed from a frequency domain hydrodynamic analysis (Wadam). The resulting computed loads are ‘complex’, comprising real and imaginary components.

The program calculates usage factors representing the amount of fatigue damage that the structure has suffered during a specific design life.