Characterisation of Non-Linear Bending Stiffness of a Submarine Power Cable through Cyclic Bending

Submarine power cables are composed of multiple components with different, sometimes non-linear, mechanical behaviour, arranged in a helical geometry. This paper proposes a novel experimental method for characterising the non-linear response of a three-core offshore submarine power cable to imposed bending. A cyclic three-point bending test was performed, during which the cable’s motion was recorded using a 3D optical measurement system to capture its defected shape. A polynomial function was fitted to the defected shape to compute the bending curvature, and the actuator force was used to determine the corresponding bending moment. This approach enables the characterization of bending stiffness in both stick and slip regimes, which are required for the evaluation of mechanical degradation due to cyclic bending. The experimental results provide valuable data for the future calibration of finite element models, supporting more accurate and reliable simulations of submarine power cables.