Mechanical Analysis Of S-lay Initial Pipelaying And Development Of Visual Simulation System

Pipelaying vessel is a kind of indispensable ocean engineering equipment in the field of ocean energy resources.Both harsh environment and complicated process of the operation will result in a large risk in deepwater pipelaying,which calls for high technical demand of operators.Therefore,the study on simulation of deepwater pipelaying system is valuable to practical engineering.According to the actual operation process of the pipelaying vessel “HYSY201”,a set of training system used for deepwater pipelaying has been built by the visual simulation technology.The training system plays an important role in staff training,project rehearsal etc.to enhance the efficiency and safety of pipelaying operation.The perfomances of the pipeline and hawser during pipelaying were analyzed.The studies on S-lay operation have always focused on establishment of the differential equations of pipelines and the comparison between different solving methods.And most methods are only employed in normal pipelaying,pipe retrieval and pipe abandonment,while they are rarely used in initial pipelaying operations.In view of initial S-lay operation,the pipeline model was built based on the theory of nonlinear elastic beam with large deflection and solved by differential quadrature method,and hawser model was built and then solved by iterative method.Considering that the boundary conditions of differential equations of pipeline and hawser are difficult to determine,the iterative method based on differential quadrature method was put forward.Thus the boundary conditions were established and differential equations were solved.For dynamic analysis of pipeline and hawser,the boundary conditions were simplified and the vibration equations of pipe and hawser were solved based on predecessors' studies.The problems of the existing simulation system have been handled and a solution was raised.The key technology of the simulation system development was studied.The overall architecture and development process of the simulation system were designed.The program of mathematical model was completed.Some issues were solved,such as transmission of massive data,sub-module's running time and so on.Finally,the function of the simulation system was improved and the software system and hardware architecture were optimized.When tested in real site,the simulation system ran stably,and the visual images were displayed smoothly.Undesirable phenomenons,such as system gets stuck,did not appear in the whole simulation of pipelaying operation.The feasibility of whole scheme was verified.By siumulating a case of initial pipelaying,the accuracy of the mathematical model was confirmed.On the basis of simulation system the pipe and hawser's response under the conditions of ocean current load and the hull's excitation was analysed.In summary,the mechanical analysis of pipeline and hawser during the initial pipelaying was completed.The iteration method based on differential quadrature method was used to solve the differential equation for the first time,which enhanced efficiency of the initial laying calculation.The boundary conditions of pipe and hawser's vibration equations were simplified properly,so the vibration equations of pipeline and hawser could be solved.The simulation system has been developed,which solves some problems such as the data transmission between different simulation subsystems.Finally,the simulation system through the specific cases was examined.Experiment results showed the simulation system were stable and visual display effect appeared well.Experiments revealed the simulation system provided important reference for offshore pipelaying operations.