| Recent years, in order to solve the increasingly shortage of energy crisis, developingoffshore wind power has become the very important energy policy in national governments.European countries are the leaders of the offshore wind power. With strong wind and highwave across the sea, its wind power resource is very rich which is suitable for the project ofoffshore wind power. The offshore wind turbine installation platform is the key equipmentto the development of the offshore wind power plant.This paper based on the study of a third generation extra large self-propelling andself-elevating wind turbine installation platform. It is a new type of ocean engineeringplatform with the function of jack-up, propelling, carriage and lifting. The platform is wideand flat, equipped with large lifting legs, huge crane with capacity of800tons, large deckloads, so the strength of its platform and legs are the difficulty. Thus, the strength finiteelement analysis of the platform and the legs was done due to the DNV rule.According to the work requirements and the arrangement, the functional loads weredetermined, including the permanent loads and the variable loads. The environment loadsincluding the wind, wave and current loads of the platform and the legs in differentconditions were calculated according to the rule. Wind and current loads were calculateddirectly on the base of the formulas and the wave loads were determined by the computersoftware according to the Stokes fifth-order wave.The finite element model of the platform was established by using MSC.Patran, and thetypical working conditions including sailing, lifting, preloading, operational and survivalconditions were determined. With reasonable boundary conditions, the strength of theplatform under12load cases was analyzed, and the stress distribution and deformationunder different conditions were gotten. The results show that the structural strength meetsthe DNV rule. The stress level under sailing condition is the minimum, and its loadingcondition is similar to the ordinary ships. After the platform is lifted, its stress levels areraising significantly. The position of the maximum stress under operational condition is atthe joint of the platform and the leg, and the stress level under the survival condition is themaximum, which is close to the permissible stress.The condition of leg under the environment was analyzed,6typical elevated conditionsincluding preloading, operational and survival were determined. Static analysis was doneand the stress distribution and deformation were gotten; the time-dependent and spacedependent wave loads were applied on the legs and the dynamic response analysis was done,and the maximum stress and displacement response curves were gotten, comparing theresults of the static analysis and the dynamic response analysis, the results are close, but theresult of the dynamic response analysis is bigger especially for the displacement, thus thestatic analysis is insufficient and the dynamic response analysis is necessary.The results and research methods of this paper could provide guidance for the study ofthe similar platforms. |
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