Fatigue Test Analysis And Damage Detection Of Typical Joints Of Jacket Platform

Offshore jacket platform is very important in the oil and gas exploitation area,which provide production and living facilities for offshore drilling,production,construction and other activities.During the operation of offshore jacket platform at sea,it will be subjected to the periodic action of various loads,which will cause fatigue damage in the internal joints of the structure.In order to monitor the fatigue damage of structure joints,this thesis studies the fatigue analysis method and fatigue crack development rule of typical joints of platform through fatigue test,finite element analysis and EMI detection.(1)The background and significance of research are outlined firstly.Then this chapter summarizes and reviews the related research status and recent technological progress of offshore jacket platform fatigue analysis and EMI detection technology,and expounds the main research contents and ideas of this paper.(2)In the second chapter,based on the engineering data of J225-1S oil field jacket platform in Bohai Bay,four kinds of typical joints are selected as the research objects,including flat-plate joint,plate-plate T-joint,tube-plate T-joint and tube-tube T-joint.Through the fatigue test of joints,the location of fatigue damage and the development of crack damage are observed and analyzed,and the fatigue life test results of joints are recorded and counted.(3)Combining with four kinds of typical joint specimens in fatigue test,this chapter establishes the finite element analysis model of four kinds of joints by using ANSYS software,calculates and analyses the high stress and high strain regions,fatigue damage distribution and fatigue life results of all kinds of joints.By comparing the results of finite element analysis with those of fatigue test,the fatigue damage and fatigue life prediction rules of joints using finite element method are summarized.(4)The EMI testing technology is introduced into the fatigue damage and crack detection of joint specimens,and the EMI testing data before and after fatigue damage are recorded.By analyzing the deviation of damage index RMSDG and conductivity-frequency curve,the rule and method of early warning and detection of fatigue damage of joints by EMI are summarized,which proves the safety and effectiveness of EMI detection...