Qualification of PWAS-Based SHM Technology for Space Applications

Abstract

The chapter refers to the results obtained in the framework of a national research project whose novelty was that concomitant outer space constraints, namely extreme temperature variations, radiations and vacuum, were applied to structures specimens to study their effect on the structural health monitoring (SHM) technology based on piezoelectric wafer active sensors (PWAS) and electromechanical impedance spectroscopy (EMIS) method of damages detection and identification. The results, in short, concern (a) the survivability and sustainability of EMIS technique, in fact the PWAS transducers survival, in these harsh conditions and (b) the developing of a methodology to distinguish between the damages of mechanical origin, and the false ones, caused by environmental conditions, which are, basically, harmless. This has resulted by observing that the splitting phenomenon of resonance peaks on EMIS signature can be associated with the occurrence of mechanical damage, making so possible the clear dissociation of the changes determined by the harsh environmental conditions.