This paper proposes a numerical approach based on a detailed 3D FE model to calculate the global mechanical behaviour and local stress state of dynamic submarine power cables. The method is applied to a three-core dynamic submarine power cable under a cyclic bending load. The numerical approach is based on the homogenization theory of periodic structures. The 3D computational domain is thus reduced to the helical period of the internal cable components, which allows the geometrical complexity and contact interactions between the components to be fully considered. In addition, the mesh size is reduced by using beam element modelling of the armour components. The study investigates the sensitivity of the cable bending behaviour to frictional interactions and manufacturing residual stresses. To validate the numerical model, the results are compared with experimental data and analytical results. The first comparison focuses on the overall behaviour of the cable under a cyclic bending load, while a local analysis compares quantities such as displacement and stresses with the results of analytical models available in the literature. The close agreement between the numerical, experimental and analytical results demonstrates the accuracy of the model in predicting the non-linear bending behaviour and local stresses that are essential for the cable design process.