Embedded Active Sensors for In-Situ Structural Health Monitoring of Thin-Wall Structures

The use of embedded piezoelectric-wafer active-sensors for in-situ structural health monitoring of thin-wall structures is presented. Experiments performed on aircraft-grade metallic specimens of various complexities exemplified the detection procedures for near-field and far-field damage. For near-field damage detection, the electro-mechanical (E/M) impedance method was used. Systematic experiments conducted on statistical samples of incrementally damaged specimens were followed by illustrative experiments on realistic aging aircraft panels. For far-field damage detection, guided ultrasonic Lamb waves were utilized in conjunction with the pulse-echo technique. Systematic experiments conducted on aircraft-grade metallic plates were used to develop the method, while experiments performed on realistic aging-aircraft panels exemplified the crack detection procedure.