Buckling of the Composite Cracked Cylindrical Shells Subjected to Axial Load

Cylindrical shells constitute the main structural components in pressure vessels and pipelines. Cylindrical shells made of fiber-reinforced composites are now being considered in the design of many components due to their high specific strength and stiffness. Buckling is one of the main failure considerations, when designing the cylindrical shells. The buckling behavior of the composite cylindrical shells can severely the compromised by introducing defect in the structure, due to high stress field generated around these defects. Defects could be generated during service due to cyclic loading or during manufacturing. A reliable operation of these structures require to understand the effects of these defects on the bucking of cylindrical shells. Finite Element Analyses are performed to study the buckling behaviour of composite cylindrical shells with and without a crack, under an axial compressive loading. The effects of the plies angle on the buckling loads and buckling mode shapes of the composite cylindrical shells are studied. Furthermore, the effects of the crack length and its orientation on the buckling loads of the composite cylindrical shells are investigated. The results indicate that the global buckling loads and mode shapes of the cracked composite shells are not significantly sensitive to the presence of the defect, for shells with a crack length less than a critical length. This critical crack length depends on the crack orientation, composite ply angles, ply sequence and the cylinder geometry. For shells with a crack longer than the critical length, the buckling load reduces and the local buckling mode at the crack tip prevail the buckling behavior of the composite cylindrical shell. The optimum ply angle for attaining the maximum buckling load is specified.