Dynamic Analysis Of J-lay Based On Finite Difference Method

Deep-sea oil has always been the hope of mankind to solve the oil problem in the future,and deep-sea oil pipeline laying technology faces many challenges.J-type pipe laying method is the most suitable method for deep-water pipe laying among all pipe laying methods,and it is becoming more and more important in oil exploitation.Based on the finite difference method and using C++ language,this paper specially developed a deep-water J-type pipelaying simulation program,and quantitatively estimated the influence of sea conditions and pipelaying vessel motion on the pipeline structure,axial tension,bending moment,stress and strain.The main contents are as follows:(1)This article first explains the research background and significance of the subject,introduces four pipe laying methods in more detail and compares the four methods,and analyzes the characteristics,advantages and disadvantages of J-type pipe laying.Summarize the current pipelaying calculation methods,and summarize the research status of domestic and foreign pipelaying calculation methods in detail.(2)According to the force characteristics of J-type pipelaying,a mathematical model of J-type pipelaying considering ocean current effect,pipeline bending stiffness,torsional stiffness and nonlinear strain-stress relationship is established.And established the kinematics model and dynamics model of the pipe-laying ship.Based on the finite difference method,a program for statics and dynamics analysis and simulation of J-shaped pipelines is developed.As an independent software,the program can deal with hydrodynamic effects and pipeline bending and torsion problems,and use finite difference method and relaxation method to solve the motion control equation of J-shaped pipeline.And compare the calculation results with the finite element method,which is faster and more accurate than the finite element method.(3)We will discuss the dynamic effects of waves and ocean currents on the pipeline.The dynamic response of the pipe-laying ship under the action of waves is calculated as the boundary condition of pipeline dynamics calculation.The changes of pipeline shape and pipeline force with significant wave height,spectral peak period,ocean current direction and ocean current velocity are studied.Quantitative analysis of the impact of the six-degree-offreedom motion of the pipe-laying ship on the dynamics of the pipeline provides a reference for actual engineering.