Lamb wave generation with piezoelectric wafer active sensors for structural health monitoring

The capability of embedded piezoelectric wafer active sensors (PWAS) to perform in-situ nondestructive evaluation (NDE) is explored. Theoretical developments and laboratory tests are used to prove that PWAS transducers can satisfactorily perform Lamb wave transmission and reception, pulse-echo, pitch-catch, and phased array functions of conventional ultrasonics thus opening the road for embedded ultrasonics. Subsequently, crack detection in an aircraft panel with the pulse-echo method is illustrated. For large area scanning, a PWAS phased array is used to create the embedded ultrasonics structural radar (EUSR). For quality assurance, PWAS self-tests with the electromechanical impedance method are discussed.