Probabilistic integrity assessment of filament wound CFRP pressure vessels

The present contribution is concerned with enhanced strategies for the integrity analysis of filament wound CFRP pressure vessels. In order to account for the effect of statistically distributed manufacturing induced imperfections, a probabilistic strategy is implemented. The imperfection location, size and geometry together with the corresponding probability distributions are determined in non-destructive evaluations of different reference vessels using X-ray computed tomography. The impact of a set of selected relevant imperfections onto the strengths in the different material directions is analysed numerically in a multiscale analysis. For assessment on the structural level, a stochastic procedure is introduced which maps the imperfections according to their probability distributions onto a macroscopic finite element model of the pressure vessel under investigation. The structural response till failure is evaluated using a customized continuum damage mechanics material model. In a sampling procedure, repeated analyses with different prescribed imperfection distributions are performed. The results are evaluated statistically, taking the individual probability of occurrence of the underlying imperfection situations into account. The method is applied in both, static burst and cyclic fatigue loading situations. The results are validated against an experimental data base concerning coupon experiments and full-scale burst experiments on reference vessels.