FAILURE PRIDICTION OF GLASS FIBER-REINFORCED FLEXIBLE PIPES UNDER INTERNAL PRESSURE

In order to explore the damage failure mechanism of glass fiber-reinforced flexible pipes under internal pressure, the theory of three-dimensional (3D) elasticity is adopted to carry out the theoretical analysis on 3D constitutive relationship of a flexible tube. Combined with a 3D Hashin-Yeh failure criterion and a nonlinear stiffness degradation model, considering the nonlinear mechanical behavior of matrix materials, a 3D progressive failure model of the flexible tube is established. The hydrostatic burst experiments are used to verify the theoretical model. And on this basis, the influence of winding angle and diameter thickness ratio on the failure load and failure mode of the flexible tube is analyzed. The analysis results show that: the theoretical model is in a good agreement with the experimental results. The winding angle has an obvious effect on the stress distribution of the flexible pipe under internal pressure; with the increase of the winding angle, the first layer failure load and the final burst failure load of the flexible pipe all present a tendency of increasing; with the increase of diameter thickness ratio, the pressure capacity of the flexible pipe decreases rapidly, but the failure mode does not change.