Damage Identification Of Oil Derrick Steel Structure Based On Stochastic Resonance

As an important bearing equipment in drilling process,oil derrick steel structure is widely used and plays an important role.However,in complex engineering environment,due to the tremendous external forces and environmental corrosion,damage will inevitably occur in the process of disassembly,assembly and use,which will cause great hidden dangers to personal and property safety.Therefore,it is necessary to judge the safety state of derrick as soon as possible.Damage identification based on vibration response is a common method of damage identification.However,in the process of collecting vibration signals,it is difficult to identify damage by weak signals because of the strong background noise in engineering.Therefore,a method of damage identification for oil derrick steel structure based on stochastic resonance is proposed in this paper.Firstly,the basic theory of stochastic resonance is studied,and the dynamic mechanism of stochastic resonance is described from the point of view of the first-order nonlinear Duffing equation.Secondly,the influence of SR system parameters,noise intensity and signal parameters on SR is studied,and the acceleration response of derrick steel structure in noise environment is extracted by using the second sampling method.A damage identification method combining stochastic resonance with instantaneous energy curvature difference is proposed.The natural frequency of acceleration response of derrick steel structure under strong noise background is identified by stochastic resonance.The cut-off frequency of band-pass filtering is determined.After filtering out noise,empirical mode decomposition is carried out,and the instantaneous energy curvature difference of first order IMF before and after damage is calculated as damage index.Through the design of the damage condition of the finite element model,the damage identification method is simulated,and the feasibility of the method is verified theoretically.Taking the derrick steel structure laboratory model as the research object,the acceleration response of derrick steel structure before and after damage was collected by acceleration sensor and signal acquisition system,and the corresponding damage index was calculated according to the theoretical method.The experimental results were compared with the actual damage,and the feasibility of the method was verified in the experiment.