The motion and deformation rate of a flexible hose connected to a mother ship

Abstract

The motion of a flexible hose connected to a mother ship continually changes according to the motion of the mother ship. In such a case, telecommunication lines protected by the hose can give rise to serious problems like cutting or connecting error. It is very important to accurately analyze and predict the motion of an underwater flexible hose, because large deformation motions of the hose in axial and normal directions determine the vehicle’s driving conditions. In a realistic situation, it is difficult to carry out an experiment because the length of the hose is at least 10 m. Therefore, the behavior has to be predicted by computer simulation. In this paper, a mother ship was considered as a rigid body with six degrees of freedom driven at a specific rudder angle and surge propulsion velocity. And to model the flexible hose, absolute nodal coordinate formulation (ANCF) was adopted, whose formulation is accurate enough to express both the large deformation effect and various forms of behavior of the flexible hose. In ANCF, the concept of continuum mechanics is introduced to derive the tensile and bending stiffness of the hose. Hence, nonlinear effects of elastic forces can be considered more effectively. Fluid drag is also imposed, which has a significant effect on both the vehicle and the flexible hose.