Finite element analysis of birdcage buckling of umbilical cable with damaged sheath

Umbilical cables are integral components of subsea production systems. In this study, the buckling failure of umbilical cable with damaged sheath under bending and compression loads was investigated. A finite element (FE) model of an umbilical cable with a damaged sheath was established using software ANSYS. The influences of the location and area of sheath defects on birdcage buckling and the impacts of the exposed area of the armor wire and the applied bending radius on the buckling mode were analyzed. The results indicate that the exposed area of the armor wire determines the buckling mode and critical buckling load. An increase in the exposed area triggered a transition from lateral buckling to birdcage buckling. Lateral buckling occurred when the exposed area was below 6%, birdcage buckling occurred when it exceeded 10%, and both types of buckling occurred when the exposed area was 8%. Furthermore, when different bending radii were applied, such transitions consistently occurred when the exposed area was 8%. This study elucidated the buckling mechanism of armor wires by considering the combined loads and damaged sheaths, thus contributing to the prevention of buckling failure.