Damage Identification Of Oil Derrick Steel Structure Based On Time-Frequency Analysis Under Noise Background

The oil derrick steel structure is the equipment that mainly plays the role of bearing in the process of oil and gas exploitation.Because the oil derrick steel structure is in a complex field working environment for a long time,it is prone to damage problems such as cracks,which cause major safety hazards and cause safety accidents.Traditional damage recognition methods are affected by external noise,which results in low efficiency and low accuracy of recognition results.Aiming at the problem of damage identification of oil derrick steel structure under the background of noise conditions,two methods for damage identification of oil derrick steel structure are proposed:based on HVD envelope spectrum transient energy curvature and AMD-HVD transient energy curvature power function Damage identification method.Using signal feature extraction technology and low-level structure information,the HVD envelope spectrum transient energy curvature and AMD-HVD transient energy curvature power functions are used as damage sensitive indicators to complete the identification.Taking ZJ70 oil derrick steel structure as an example,through damage identification numerical simulation,the two indexes are analyzed to be sensitive to oil derrick steel structure damage;through the damage identification experiment,the feasibility and accuracy of the method are verified.The theory of HVD decomposition is analyzed in depth,and the influence of noise on HVD is studied through simulation analysis.Envelope analysis of the HVD principal component is performed to extract the principal component transient energy,and the transient energy curvature of the HVD envelope spectrum is used as the damage sensitivity index.A damage feature extraction method of the HVD envelope spectrum transient capability curvature is proposed.The AMD theory is studied,and the influence of noise on AMD is discussed through the comparison between AMD and EMD simulation.It is concluded that AMD can filter out some noise.By designing AMD as a band-pass filter,the band-pass filtering function is realized.Compared with the conventional band-pass filter,the signal leakage phenomenon caused by the window function in the traditional band-pass filtering process is avoided.Combining AMD and HVD,and using the power function of curvature power of AMD-HVD transient energy as the damage sensitive index,a damage feature extraction method based on the power function of curvature power of AMD-HVD transient energy is proposed.Model the finite element experimental model of the ZJ70 derrick steel structure,perform modal analysis on the finite element model to obtain the natural frequency and mode shape of the derrick;perform transient dynamic analysis on the finite element model under random and impact loads to obtain the dynamics of each node The response provided data for subsequent damage feature extraction and damage identification of the derrick steel structure.Two damage identification methods are proposed based on the damage sensitive index: damage identification method based on HVD envelope spectrum transient energy curvature and damage identification method based on AMD-HVD transient energy curvature power function.Based on the damage simulation analysis of the finite element model of the derrick,the damage simulation conditions were designed.Two damage identification methods were applied to the damage simulation identification of derrick steel structure,and the relationship between the damage index and damage was obtained,and the damage identification rules of the two methods were summarized.Taking the laboratory ZJ70 oil derrick steel structure model as the experimental object,using the HVD envelope spectrum transient energy and AMD-HVD transient energy curvature power function as damage sensitivity indexes,damage simulation experiments were carried out on the derrick experiment model.The experiment successfully identified the damage and verified the feasibility of the two methods;the experimental results have a good correspondence with the experimental conditions and verified the accuracy of the two methods.