Manufacturing and testing of active composite panels with embedded piezoelectric sensors and actuators: wires out by molded-in holes

Abstract

This work presents manufacturing and testing of active composite panels (ACPs) with embedded piezoelectric sensors and actuators. The composite material employed here is a plain weave carbon epoxy prepreg fabric with about 0.33 <i>mm</i> ply thickness. The piezoelectric patches employed here are Continuum Control Corporation, CCC, (recently Continuum Photonics, Inc) active fiber composite patches with 0.33 <i>mm</i> thickness, i.e. close to the composite ply thickness. Composite cut-out layers are used to fill the space around the embedded piezoelectric patches to minimize the problems associated with ply drops in composites. The piezoelectric patches were embedded inside the composite laminate. High-temperature wires were soldered to the piezoelectric leads, insulated from the carbon substructure by high-temperature materials, and were taken out of the composite laminates employing a molded-in hole technique that reduces the stress concentration as opposed to a drilled hole, and thereby enhancing the performance of the composite structure. The laminated ACP’s were co-cured inside an autoclave employing the cure cycle recommended by the composite material supplier. The curie temperature of the embedded piezoelectric patches should be well above the curing temperature of the composite materials as was the case here. The manufactured ACP beams and plates were trimmed and then tested for their functionality. Vibration suppression as well as simultaneous vibration suppression and precision positioning tests, using PID control as well as Hybrid Adaptive Control techniques were successfully conducted on the manufactured ACP beams and their functionality were demonstrated. Recommendations on the use of this embedding technique for ACPs are provided.