Application of active structural health monitoring technique to aircraft fuselage structures

摘要

Abstract: Damage identification of complex structures can beperformed using an Active Structural Health MonitoringSystem (ASHMS) utilizing an array of piezoceramic (PZT)sensor- actuators and an electromechanical impedanceanalyzer. Based on the theory of electromechanicalimpedance for surface-bonded collocatedsensor-actuators, the system provides the means ofimplementing effective Non-Destructive-Evaluationhealth monitoring to a structure at any point in itslife cycle. When integrated into a structure, the ASHMScan identify the location and extent of damage througha statistical analysis algorithm which compares theelectromechanical admittance of the structure's currentcondition with the structure's `baseline' conditionover a defined frequency range. This paper presents amodel independent method of structure damageidentification based on statistical analysis of thechanges in the electromechanical impedance of thestructural response. Using a small section of anairplane fuselage with free-free boundary conditions asthe test structure, a prototype system has beensuccessfully developed which automatically measures andcollects the electromechanical admittance data from anarray of transducers. The measurement system developedcan apply large voltages to the PZT transducers, whileaccurately determining the spectral and harmonicinformation of the frequency range of interestresulting in an increase in the measurement sensitivityand the area monitored by a single transducer. Thesystem can accurately measure and collect large amountsof structural information with a limited number oftransducers in a very short period of time. Thepost-analysis of the measured structural variation canbe performed with the advanced signal processingalgorithm presented herein within seconds of datacollection. The results show a remarkable accuracy ofdamage location identification for a complex structure.The basic research conducted so far indicates that theASHMS and associated processing techniques have apromising potential for health monitoring of realcomplex structures.!5