Crack Open/Close Effect on Impedance Based System of Structural Health Monitoring

Abstract

The purpose of this article is to investigate the fatigue crack open/close effect to electromechanical impedance (EMI) of the system ‘host structure/ piezoelectric transducer’ and to estimate of efficiency of effect application for structural health assessment of aircraft structures. The experimental study was performed using the PI Ceramic a piezoelectric transducer PIC151 of 0.5 × 10 × 50 mm (PZT). Two types of the 1.14 mm aluminum alloy thin-walled samples were used as the host structures for testing of different geometrical configurations. The PZT were glued at the surface of sample by the Epoxy Paste HYSOL EA 9309.3 NA. The sample was subjected to static load of different levels and at each of them EMI and electrical capacitance of the piezoelectric transducer were measured by the impedance analyzer C60 (Cypher Instrument). Combined effect of the load and the boundary conditions (partial detachment of the sample fixing zone) was also investigated. In all tests the significant effect of load to the different signatures of the EMI and the PZT capacitance was observed. For the analysis, designing and calculations software like Cypher Graph, Microsoft Excel were used. The obtained results make it possible to assess the main properties of the effect of the fatigue crack open/close and demonstrate the sensitivity of different parts of EMI to the action of external load.