Research On Damage Detection Of Offshore Platform Based On The Modal Parameter

Gradually with the offshore oil and gas resources is exploited, offshore platform is moreand more important status in the process of exploiting. However, most of the platform hasreached even more than the service life at home and abroad. In order to ensure the safety ofoffshore production, to avoid heavy losses, the offshore platform structure damage detectiontechnology research has become a hot research topic at home and abroad.Were reviewed in this paper damage detection technology of offshore platform on thebasis of domestic and foreign research present situation, understand the trend in recent yearsthe global detection method based on modal parameters of structural damage detectiontechnology is an effective, accordingly, the model of jack-up platform as the research object,a preliminary study of the method in the application of offshore platform structure damagedetection, and the load on the modal parameters of the offshore platform structure.First of all, introduced the basic principle of modal analysis and finite element analysismethod based on computer work, experimental modal analysis and modal analysis of thebasic method and principle. Then simply supported beam as the research object, respectivelyby finite element analysis work, experimental modal analysis and modal analysis are verifiedin the simply supported beam, the results show that experimental modal parameters and thework is the result of modal parameters is consistent, so can change to replace each otheraccording to the test environment. And compared with the measured modal parameters,determine the jack-up platform structure modeling, finite element simulation analysis usingentity unit using experimental modal analysis of a jack-up platform modal test and analysismethod of the model.Then on the basis of the study, with no damage and damage the jack-up platformstructure under the condition of the finite element simulation analysis, and the platformstructure of the two kinds of working conditions is hammering method experimental modaltest, the test data using PolyMAX method to extract the modal parameters, the simulationresults with the measured modal analysis results, the structure damage results in the decreaseof modal frequency, and two kinds of analysis method of modal frequency and vibrationmode, shows the validity of the finite element modeling, at the same time, combining withthe change of the modal vibration mode, can determine the position of the damage.Last simply supported beam as the research object, theoretical analysis of the axialtension and pressure influence on structural modal frequency, then the static, no-load and load under different load working condition of three kinds of jack-up platform model experimentalmodal testing, modal parameters extraction using PolyMAX method, the modal analysisresults shows that the load of modal frequency of the platform structure has great influenceon the change of the modal parameters, such as in the actual offshore platform structuremodal test should be given consideration.