| The durability of reinforced concrete has a great impact on the structural bearing capacity,while the corrosion of steel bars is the main reason for the degradation of structural durability.Acoustic emission testing of reinforced concrete structures,early detection and accurate inspection of concrete corrosion,can ensure the safety and service life of the structure.In the aspect of rust concrete corrosion monitoring,the acoustic emission technology can reflect the rust damage degree of reinforced concrete and locate the rust area.In this paper,In this paper,the rust damage process of reinforced concrete is studied.The clustering analysis is used to identify the different rust damage states.The design pure shear test verifies the reliability of the moment tensor inversion to identify the concrete crack category,and then explores the rust expansion.The generation process of cracks;a method for calibration of simple and effective acoustic emission systems is proposed and implemented.Based on the above research results,this paper develops an acoustic emission signal processing system for rust concrete acoustic emission signals.In this paper,the following conclusions are obtained through research:(1)Based on the signal generator and oscilloscope,the acoustic emission source signal is generated by the broadband sensor REF-VL,and the acoustic emission channel detection is realized for the whole system of sensor,gain and acoustic emission host.Through further comparison and analysis,the sensitivity and frequency response curves of acoustic emission sensors are obtained.The results show that the method is simple in operation and high in reliability,and the results generated by MATLAB GUI are clear and complete.(2)Accelerated corrosion of reinforced mortar specimens is carried out by anodizing accelerated corrosion method,and acoustic emission signals were collected in the process of accelerated corrosion using acoustic emission technology。The curve of cumulative AE hits combined with the historical index and the severity index can reveal the law of corrosion damage evolution of reinforced concrete.Dividing the degree of rust damage of reinforced concrete into three stages by strength analysis.Finally,the k-means clustering analysis algorithm is used to cluster the acoustic emission signals to obtain the acoustic emission characteristics of each damage stage.The results show that the signal characteristics corresponding to the generation and development stages of cracks are large energy and small quantity,which can be used as precursor characteristics of reinforced concrete rust expansion cracking.(3)Based on the principle of seismic moment tensor,MATLAB moment tensor solving program is written by ourselves according to the SIGMA moment tensor analysis method,and design the test verification program correctness.It is concluded that shear fracture occurs at the precast crack in the unilateral and bilateral loading tests.The shear ratio at the prefabricated crack is 89.4%,which proves the accuracy and applicability of moment tensor program in analysis of acoustic emission source mechanism.The program of moment tensor is applied to the accelerated corrosion test piece for calculation,and compared with the failure results of the test piece,the effectiveness of moment tensor inversion method applied to nondestructive testing of reinforced concrete structures is discussed.The results show that acoustic emission nondestructive testing technology based on moment tensor can effectively identify the crack type of the structure for the process of rust expansion and cracking of reinforced concrete.Based on the above research results,this paper developed an acoustic emission system for corrosion of reinforced concrete.The research results of this paper can be directly applied to the analysis of corrosion signals of reinforced concrete,and provide a feasible approach and reference for acoustic emission signal analysis system based on MATLAB GUI. |
