Preliminary acousto-ultrasonic investigation for multi-parameter transducer self-diagnostic system in composites

Commercial aerospace vehicles are demanded to withstand harsh conditions with a low weight impact. Composites are massively used to achieve the optimal trade-off about such performances. However, actually the effect of barely visible flaws on the damage tolerance approach reduces strongly the benefits introduced. Structural Health Monitoring is the most promising technology aimed to compensate such shortcoming aspect. Among several methods, guided waves are efficiently adopted to detect hidden flaws using small integrated transducers, whose reliability is affect by hazard operating conditions. The self-sensing of such devices became indeed crucial to reduce false alarms in damage detection. Although the electromechanical impedance technique is proved to be effective for sensor fault due to different degradation levels, several failures may induce different effects warning a possible compensation. The present work discusses such effects with a comprehensive acoustoultrasonic experimental campaign. The combined wave propagation and electromechanical impedance investigation mostly assesses the necessity and the feasibility of a multi-parametric self-sensing system. This approach is verified performing several measurements using Laser Doppler Velocimetry (LDV) as well as electromechanical signature measurements on typical aeronautical composites.