Damage Identification Based On Piezoelectric Impedance Technologyand Fuzzy Inference

In recent years,the application of piezoelectric smart materials has become more and more extensive in the field of structural health monitoring.In this paper,the use of piezoelectric impedance technology and fuzzy logic system to conduct structural damage identification research.First,the theoretical model and research status of the piezoelectric impedance method in the field of structural damage identification are reviewed;then,a finite element model of the aluminum beam is established,and the relationship between the aluminum beam damage status and the impedance signal of the piezoelectric sensor is studied by numerical analysis,and the root mean square index(RMSD)is extracted from the electrical impedance signal as the damage index.The results show that the higher the damage,the larger the RMSD value;the closer the sensor is to the damage,the larger the RMSD value.In addition,the effect of ambient temperature on the piezoelectric impedance signal was studied using numerical simulation methods.The results show that the temperature increase is proportional to the RMSD value and has an approximately linear relationship.In order to verify the correctness of the finite element numerical simulation results,the paper carried out experimental research,using piezoelectric sensors to carry out damage identification test research on aluminum beams,the results show that the experimental test results are in good agreement with the numerical simulation results,in which the finite element simulation is verified.In this paper,an ECC(Engineering Cementious Composites)reinforced concrete beam was also produced to verify the ability of piezoelectric impedance technology to identify damage to civil engineering structures,and to test the conductance signal(the real part of reciprocal of electrical impedance)of the concrete beam under different damage conditions,extract the RMSD as the damage index from the measured conductance signal.The test results show that the RMSD value of the conductance signal increases with the increase of the damage;the RMSD values of the piezoelectric sensors placed in the middle of the concrete beam span are relatively larger,which proves that the piezoelectric sensor is more sensitive to local damage in the vicinity.Hence,the RMSD value of the piezoelectric sensor array can be used to identify the degree and location of structural damage.Finally,the paper uses fuzzy logic theory to analyze the aluminum beam finite element numerical simulation and experimental test results,based on the electrical impedance data to establish a fuzzy rule base,and use the remaining data as a test group to verify the correctness of the fuzzy inference system.The results show that the predicted values of damage and location are basically close to the real value with satisfied accuracy.Considering that the electrical impedance signal will be affected by environmental noise in the actual measurement,different level of noise was added to the piezoelectric impedance data,and uses a fuzzy logic system to conduct damage prediction for the FE and test data of aluminum beam,and the results show that the fuzzy logic system has good anti-noise ability.In conclusion,the paper uses fuzzy logic system combined with piezoelectric impedance technology to provide a new idea for the application of piezoelectric impedance method in the field of structural damage identification.