The influence of manufacturing variances on the progressive failure of filament wound cylindrical pressure vessels

Developing modelling methodologies to characterise the post first-ply failure behaviour is an ongoing tough challenge. In this study the results of a progressive failure algorithm based on a sudden mode-dependant degradation methodology are presented and applied to filament wound cylindrical pressure vessels subject to an internal pressure undergoing first ply-failure, post failure and ultimate failure. In this case, the material properties are degraded according to the failure mode detected from the homogenised stresses at lamina level. The numerical models were corroborated with experimental tests results. Influences due to manufacturing divergences from near perfect samples such as material thickness and voids are also investigated. The results show that the laminated pressure vessels investigated are able to sustain considerable higher pressures beyond the predicted first-ply failure of approximately three times as much. However the progression of failure and pressure vessel response was found to be highly dependent on manufacturing divergences. This property of fibre reinforced composites gives rise to the importance of successfully modelling the post first-ply failure of these novel materials to enable the engineer to carry out analyses of structural integrity beyond their design loads and possibly exploit their advantages and increase confidence in their design and application.