A Finite Element Method for Calculating the Applied Top Tension and Static Configurations of Extensible Marine Riser with Specified Total Arc-Length

摘要

A variational formulation of an extensible marine riser is formulatedrnbased on the work-energy principle. The total unstretched arc-length ofrnmarine riser is specified while the top tension is not yet exactly knownrnat the equilibrium position. A Lagrange multiplier is introduced inrnorder to impose the constraint condition, which is the specified totalrnarc-length of the riser. The system unknowns are composed of thernnodal degrees of freedom and the Lagrange multiplier. The system ofrnnonlinear finite element equations is derived based on the finite elementrnprocedure. The numerical solutions of the nonlinear system arernobtained by the iterative method. The results show that the Lagrangernmultiplier is identified as the value of top tension adjusting thernspecified top tension in order to maintain the marine riser inrnequilibrium condition.