PHAReB: Pressure Hull Analysis on a Reliability Basis

The pressure hull of a submarine is an extremely important component of the design, not in the least since it contributes largely to the displacement. The structural integrity is nowadays established by nonlinear finite element analysis preceded by a preliminary design based on analytical methods developed in the past century. These formulations can still be found in the Rules of Classification Societies.

The analytical approach shows serious discrepancies with the numerical simulations, but that is not considered to be a problem since the final FE analysis will produce accurate results. Even a considerable analysis time is acceptable when the design is more or less finished.

PHAReB aims at the uncertainty involved when the design ends up in an actual structure. The geometry and material properties will show a variation around the mean value, and this results in a probability of collapse instead of a deterministic collapse pressure with the application of safety factors. However, for reliability analysis the time required for one single nonlinear analysis is a serious obstacle. A large number of repetitions is required and even HPC is not a way out. That is why PHAReB picks up the challenge to minimise the discrepancies between the analytical and numerical approach.