Research On Structural Damage Identification Method Based On Recurrence Plots Analysis

The research of structural damage identification method is an important subject in the field of structural health monitoring,and many methods and techniques of structural damage identification based on time domain and frequency domain have been put forward and developed continuously.However,most of the actual engineering structures are stimulated by non-stationary signals,and most of the actual engineering structures are nonlinear structures,and the structural vibration response is characterized by strong non-stationary characteristics once the engineering structure has been damaged.For Non-stationary Vibration response signals of time-varying structures,the model and method of linear time series analysis can not accurately extract the structural damage characteristic information in non-stationary signals.At present,a large number of scholars at home and abroad have put forward a lot of nonlinear time series analysis methods applied in the field of structural damage identification,in which recurrence plots is an advanced Nonlinear time series analysis method,which can directly reflect the phase space manifold of dynamical system and reveal the characteristics of system dynamics.When the structural dynamic parameters change,the dynamic responses will change,and by recurrence and recurrence quantization analysis of the dynamic response of each damage condition,the recurrence rate index and the TT index of the recurrence quantization measure can effectively identify the structural parameter change.Based on the analysis of the vibration response of reinforced concrete beams in civil engineering structures,this paper uses recurrence plots and recurrence quantization analysis to study the nonlinear damage identification of structures.The research contents are as follows:Firstly,the free vibration of a single Freedom Spring vibrator(duffing oscillator)is numerically analyzed,by changing the dynamic parameters such as stiffness,damping coefficient and non-linear coefficient,the dynamic response of spring oscillator is obtained by recurrence plots and recurrence quantification analysis,and the numerical relation between recurrence quantization analysis and dynamic parameter change is summed up,the recurrence rate and TT index are determined as the theoretical basis of structural damage index.Secondly,a numerical model of a single freedom cosine-type breathing fracture cantilever beam is established,and by changing the depth of the cantilever beam crack to simulate different degrees of damage,the vibration response of the cantilever beam with different degree of damage is established by the recurrence plots and the recurrence quantification analysis.This paper compares and analyzes the effect of the recurrence quantization measure and the TT index to recognize the nonlinear damage degree of the cantilever beam under the pulse excitation.Thirdly,The mid-span acceleration response of a reinforced concrete test beam subjected to the impact load during the gradual loading process was analyzed,in this paper,a recurrence plots of 10 hammer-hit excitation response under different damage conditions is obtained,and recurrence quantification analysis is made to obtain the recurrence rate and TT index of the recurrence quantization analysis,which is used as the damage index.The damage identification effect of two damage indexes on RC beams was compared and analyzed.The experimental results show that the recurrence rate index can recognize the non-linear damage of reinforced concrete,but it is easily influenced by the environment factors such as the excitation size and lack of numerical stability.The TT index can not only identify the small damage of RC beams,but also can identify the large damage caused by large cracks after the reinforced concrete reaches the ultimate bearing capacity.The comparison and analysis of the damage identification results of the RC beams can show that the TT index based on recurrence quantization analysis is an ideal damage index to recognize the nonlinear damage of RC beam structures.