The Research Of Structure Health Diagnosis Based On The EMI And The ANN Technology

In recent years, the EMI (piezoelectric impedance) technology has been applied to the health diagnosis detection of materials such as steel beams, aluminum beams. In this paper, some further study of healthy intelligent diagnosis based on the EMI technology is carried out, mainly about experimental design and processing data.On the base of theoretical derivation experiments was design to measure the impedance signal, and ANN net was design to process the signal to diagnose the health condition of the structure.Research object including piezoelectric coupling beam and its crack damage, additional excitation signal and static load signal; and then tried to design EMI transducers to detect the health status of aluminum beams, concrete structure.Specific research content and results are:1) Introduced the basis of the principle of EMI technique-based diagnostics and health diagnostic techniques in theory, proved that by measuring the quantity of electricity changes of PZT piezoelectric ceramic can determine whether structures mechanical impedance changes. First introduced piezoelectric material and the associated piezoelectric equations; Then, combined with the principle electromechanical analogy with structures constructed of piezoelectric ceramic "PZT-structures" coupled systems, analyzed the relationship between electrical impedance and structural coupling mechanical impedance.2) Design experiment platform with WK6500B impedance analyzer tocarry out health diagnostic experiments based on EMI (the piezoelectric impedance) technology. Choose a good sweep band to carry out structure health detection experiments, subjects of the study including crack and abnormal external excitation signal inside a building, pressure, and other sub-health state. Meanwhile, by means of finite element simulation while the case of the bad control of the temperature, length, etc. need to be controlled with high precision.3) Combined with ANN (Artificial Neural Network) method of processing data on aluminum beam structure internal crack location, depth, and external abnormal signal, pressure quantitative identification. Identified the coupling beam crack depth and crack location, as well as the additional incentive vibration frequency and static load force size of the coupling beam. After doing a lot of experiments, analysis and research, successed to diagnosis to certain extent of aluminum beam state.4) Two EMI transducters were designed based on the theoretical principles and experimental of EMI technique. Platform with WK6500B impedance analyzer were designed to diagnosis the aluminum beam crack and concrete; Not only the crack depths of the aluminum beam structures were quantitative diagnosised, but also crack occurrence of concrete beam structures were preliminary diagnosis.