Failure of Thick-Wall Filament Wound Plastic Pipes under Internal Pressure

Experiments and axisymmetric laminate analysis have been carried out to evaluate the progress of failure in thick-wall filament wound glass/epoxy pipes under internal pressure. The initial failure of laminates was controlled by matrix cracking perpendicular to the glass fiber direction. The laminated pipes wound with ±89.1/±5° showed the initial failure at low pressure and the failure progressed sequentially accompanying with sounds. On the other hands, for ±58° laminated pipes the final failure which gives leakage took place at the same time as the initial failure. These experiments coincided with the results of axisymmetric laminate analysis. In order to accomplish the resistance against high pressure failure, a flexible matrix which prevents matrix cracking was introduced for ±55° laminated pipes. The final failure pressure of the flexible matrix pipe was about three times of that of the original matrix pipe.