Design and characterization of the CLoVER transducer for structural health monitoring

Abstract

Structural health monitoring (SHM) is the component of damage prognosis systems responsible for interrogating a structure to detect, locate, and identify any damage present. Guided wave (GW) testing methods are attractive for this application due to the ability of GWs to travel over long distances with little attenuation and their sensitivity to different damage types. The Composite Long-range Variable-direction Emitting Radar (CLoVER) transducer is introduced as an alternative concept for efficient damage interrogation and GW excitation in GW-based SHM systems. This transducer has an overall ring geometry, but is composed of individual wedge-shaped sectors that can be individually excited to interrogate the structure in a particular direction. Each wedge-shaped sector is made with piezoelectric fibers embedded in an epoxy matrix surrounded by an interdigitated electrode pattern. The multiple advantages over alternative transducer concepts are examined. In particular, it is shown that the geometry of each sector yields actuation amplitudes much larger than those obtained for a ring configuration under similar electric inputs. The manufacture and characterization procedures of these devices are presented, and it is shown that their free strain performance is similar to that of conventional piezocomposite transducers. Experimental studies of damage detection simulating the proposed damage interrogation approach are also presented.