Research On Structural Health Monitoring Of Offshore Platform Based On Signal Analysis

The working environment of offshore platform is very complex,and the damage of platform structure can not be avoided because of the combined action of wind,wave,flow and other loads.The damage will cause a decrease in the carrying capacity of the structure,resulting in catastrophic accidents and claiming incalculable losses of life and property.Therefore,in order to obtain the health status of offshore platforms in a timely and accurate way,it is of great theoretical significance and broad application prospects to carry out real-time health monitoring research of offshore platforms.Firstly,this paper systematically introduces the present research status and research results on health monitoring methods for offshore platforms based on vibration response at home and abroad.It describes the basic principle of wavelet analysis theory and introduces its application in signal singularity detection in wavelet analysis.It also summarizes the research results of related theory and application and thus studies the feasibility analysis of the application in the offshore platform health monitoring of wavelet.According to the routine health monitoring contents and the method of health monitoring in this paper,the frame structure and principle of the data acquisition system for offshore platform health monitoring are given.Secondly,because wavelet analysis has the advantage of multi-scale analysis,it can analyze the local characteristics of signals.Therefore,the damage prediction of a jacket offshore platform is studied by wavelet analysis.Daubechies wavelet is used to carry out wavelet transformation to the measured signals of the numerical simulation,and the singular points of the signals are identified,then the time of the structure damage is identified.The damage warning effect of wavelet analysis method is applied to study different damages,different damage modes and different signal-to-noise ratio.Some useful conclusions are obtained.Finally,when the structure is damaged,the energy of wavelet packet will change obviously.According to this property,the signal is analyzed by wavelet packet.The change rate index of the wavelet packet is compiled,using the confidence upper limit as the warning value.The difference between the wavelet packet energy change rate and the upper confidence limit is positive at the two ends of the damaged member,and the single damage and multi damage location is found.The relation between the magnitude of wavelet packet energy change rate and the degree of damage and the influence of measurement noise on damage index are also analyzed.