Numerical Solution of the Beam Equation for Beams subject to Large Deflections

The bending stiffness of subsea cables and umbilicals can be identified from physical tests where the cable is supported at both ends and then pushed or pulled at the center. The beam equation can be used to calculate the bending stiffness from the measured force and the measured deflection. However, a study performed by Nexans Norway AS shows that the beam equation oversimplifies the cables’ properties and thereby disregards significant effects. This paper extends the beam equation into the case of large deflections, which is the second milestone of the work on deriving an accurate model. Within a realistic range of cable deflections, the force calculated by the novel model differs with up to 20% compared to the previous, oversimplified model. From the author’s point of view, this large difference justifies the somewhat increased complexity and computation time of the novel model.