Semi-physical Simulation Of Marine Flexible Pipe And Cable’s Fatigue

The marine flexible tubes and cables are including flexible marine risers, dynamic submarine cables and umbilicals.Because of its importance in the oil and gas development, its various failure mode has been an issue of concern. The tube/cable’s fatigue analysis has complicated process, high cost, large uncertainties and other characteristics in the research of these problems and is more difficult than the general problem of the marine flexible tube/cable. Compared with other structural fatigue research project, there is no good means for umbilical’s fatigue stress amplitude calculation. Therefore, the semi-physical simulation experimental study the umbilicals fatigue is the most effective way.In this paper, the marine flexible tube/cable fatigue semi-physical simulation experiments described in detail. First introduce the basic material fatigue theory and marine flexible pipe cable structure. According to the structural characteristics of the different umbilicals, the fatigue stress amplitude calculation of its components, and the need of fatigue tests were discussed. Then describes the marine flexible tube/cable’s pure bending fatigue tests have been undertaken, including two different marine flexible pipes and a dynamic submarine cable testing. The significance of semi-physical simulation experiments is proposed after analysising the limitations of these experimental methods and results. Turning the flexible tube/cable’s reign load to the load value of the experimental simulation is an important preliminary work of carrying out experiments. The main process is the overall reign analysising marine flexible tube/cable, and then the fatigue load count statistics and developing appropriate experimental load modules.The flexible tube/cable fatigue experimental setup is a overall of coordination integrated multiple subsystems, including the loading mechanism, control system, monitoring system, oil source systems and ancillary equipment.Bending stifferner as an important component protect the specimen from excessive flexural failure while test.also affect the specimen’s deformation state under load.This paper introduces the mechanical analysis and design method of bending stifferner.Loading mechanism, control systems and oil-source design is directly related to the deformation state when flexible tube/cable specimen under experimental load force.So the deformation compatibility analysis of flexible tube/cable specimen under load is the highlights of device design.The coordinate relations of specimen’s experimental load and deformation is analyzed by theoretical analysis, numerical simulation and experimental validation,then detailed designs of the experimental system are taken.Finally calculate the specific parameters of the actuators,oil source and other main part of experimental setup,and give the part of the schematic of the loading mechanism.