SENSITIVITY ANALYSIS OF PARAMETERS FOR FPSO MODEL UPDATING

This paper presents parameter sensitivity analysis for a FPSO numerical model updating. Generally, model test data are considered a better presentation of physical phenomena than its numerical counterpart. To minimize the discrepancy, model updating is of pragmatically importance. Model updating of a certain FPSO can be achieved by specific steps. In each step, the required properties of numerical model and test results are matched by means of tuning of the related parameters. To avoid inefficiency and physical meaning loss resulting from large modification of parameters which are insensitive to objective properties, parameter sensitivity analyses using the direct method are conducted in this paper. The investigated parameters mainly are the FPSO's mooring line length, mooring line mass per unit length, mooring line cross-sectional area, fairlead position, FPSO hydrostatic stiffness, FPSO mass properties, linear and quadratic damping coefficients. According to the different stages of FPSO model updating, the objective functions are set to be the FPSO's mooring line pretension, mooring system horizontal restoring force, the natural periods of the FPSO's 6 degree of freedom motions and the standard deviation of motion response spectra under irregular waves.