Research On Feature Extraction Of Vortex-induced Vibration And Damage Of Marine Risers Based On Signal Analysis

Marine risers are important structures to explore and develop deep-sea oil and gas resources.Risers are subjected to vortex-induced vibration in ocean environment,which will cause fatigue damage to the structures.Earthquake,tsunami,corrosion by seawater and marine organisms,and collision between risers can all cause damage to the risers.Structural health monitoring can make sure whether the structure is damaged and the location as well as the severity of the damage by extracting the signal features.At present,this technology has achieved rich research results in civil engineering and offshore platforms.However,there is a lack of such research in the field of marine risers.In order to explore methods that can effectively extract the vortex-induced vibration and damage characteristics of marine risers,this paper carried out the following research:(1)Model experiments on vortex-induced vibration were carried out to obtain the strain signals of marine risers.Then,using Hilbert-Huang Transform and Wavelet Transform for signal processing,the feature extraction effects of the two methods were compared and analyzed.The results show that the two methods can effectively extract the signal features,and have a good ability to recognize the various frequency components in the signal,but there are still some differences in details.In terms of time and frequency resolution,wavelet time spectrum is better than Hilbert spectrum.However,HHT transform can get the exact result of signal frequency composition and content,which is not possible in wavelet spectrum.(2)Finite element analysis software ABAQUS was used to establish the damage model of the marine risers,the damage characteristics were extracted by the two methods mentioned above,and the changes of the damage characteristics under different damage degrees were compared.The results show that both methods can extract damage characteristics of marine risers,and Wavelet Transform is better than Hilbert-Huang transform in terms of effect.The study confirmed that the two methods can effectively extract vortex-induced vibration and damage features of marine risers,which can provide the method and theoretical basis for the health monitoring of risers,as well as the research on the fluidsolid coupling characteristics of risers and the prediction of riser collisions.