Test And Application Of Structural Damage Identification Based On Impendance Method

Spherical tanks, heat exchangers, towers and other welding equipments arewidely used in petrochemical, aerospace, marine and transportation industries.With the scale, temperature and pressure of equipment being larger and higher,the damage which is easy to appear in the weld such as crack poses a hugethreat to their safety, so it is necessary to carry out health monitoring. In thispaper, the piezoelectric impedance technology applied to damageidentification of the weld in welded structures in petrochemical field has beenanalyzed and a series of tests have been carried out. The feasibility ofpiezoelectric impedance method used in damage identification of weldingequipment has been analyzed specifically. And then, positioning test andnumerical simulation of the metal material with damage such as cracks andholes have been completed. After that，the relationship between the change ofimpedance curve and the crack location has been gotten initially, whichsupported the feasible monitoring method. Finally, a preliminary test has beentaken. The main content was as follows:(1) This paper has analyzed the current status of security means of weldedstructures as well as the lack of current non-destructive testing means, and hasexpounded the significance of the piezoelectric impedance applied to thedamage identification of welded structures.(2)The development of piezoelectric impedance technology at home andabroad has been introduced as well as a detailed study of the establishment ofthe mechanical model and previous model experiment.(3)With large amounts of data from the test of piezoelectric impedancemethod, it has been found that the correlation coefficient ofimpedance-frequency curve before and after the injury appeared and thelocation of injury was a linear relationship.(4) Using the finite element analysis software, the impedance of thepiezoelectric wafer as well as the impedance change of plate with cracks hasbeen simulated. The result was basically the same as the actual test conclusion.(5) Based on the conclusion of test and numerical simulation, a newdamage identification method of weld in welded structures has been set up.The test result has showed that the measurement error of the method was in anacceptable range.