Abstract
In order to perform meaningful fatigue life analyses and estimate the state of fatigue of existing submarine cables, detailed knowledge of the fluid-structure interaction for a variety of load cases as well as reliable data on the fatigue behaviour of the complex overall cable is required. To protect the conductor, submarine export cables consist of several layers. Here, a lead sheathing ensures complete radial water tightness. Regarding transient loads, due to the low fatigue resistance of lead this layer turnes out to be the weak point of the cable geometry. Accordingly, experimental investigations on full-scale cables are carried out in order to proof the cable’s stress-cycle curve.
Fully flexible, nonlinear time domain simulations are then used to determine transient stress distributions within the cable for defined load cases. Here, a non-linear model based on reduced finite element structures was developed and implemented. Finally, based on the fatigue data previously determined during the experiments, a damage analysis is carried out using rainflow-counting.
