SAGA is used on fracture mechanics projects where a standard SN Curve approach is not considered appropriate.  The fracture mechanics program is based on the Paris' Law approach described in SSC-409 and allows for the evaluation of crack growth of external and internal crack types typically found in ship structures.

The loading driving the fatigue stress ranges are defined by a weibull distribution of a stress range calculated by loading and solving an FEA model. The model program allows us to investigate the effect of:

  • Initial crack length

  • Residual stress in the structure

  • Compressive stress

  • Wheeler retardation model

  • Shape geometry effects in case of a damaged area

Finite Element Model stress ranges are used in SAGA to calculate a fracture damage ratio where amount of cycles in a design event is presented as a ratio of amount of cycles to failure.