This work presents the 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 0.30 mm ply thickness. A cross-ply type stacking sequence is employed for the ACPs. The piezoelectric flexible patches employed here are Active Fiber Composite (AFC) piezoceramics with 0.33 mm thickness. Composite layers with openings are used to fill the space around the embedded piezo patches to minimize the problems associated with ply drops in composites. The AFC piezoceramic patches were embedded inside the composite laminate. High-temperature wires were soldered to the piezo leads, insulated from the carbon substructure by high-temperature materials, and were taken out of the composite laminates employing cutout hole, molded-in hole, and embedding techniques. The laminated ACPs with their embedded piezoelectric sensors and actuators were vacuum bagged and co-cured inside an autoclave employing the cure cycle recommended by the composite material supplier. The Curie temperature of the embedded piezo patches should be well above the curing temperature of the composite materials as was the case here. The capacitance of the piezoelectric patches was measured before and after cure for quality control. The manufactured ACPs were trimmed and then tested for their functionality. A finite element analysis (FEA) model was developed to verify the free expansion of the AFC FEA. Next, the FEA model of the manufactured ACP was developed based on the AFC FEA free expansion model and was employed to test the functionality of the AFCs embedded within the ACPs. Both static and dynamic FEA results of the modeled ACPs showed very good agreements with their corresponding experimental results. Finally, vibration suppression as well as simultaneous vibration suppression and precision positioning tests, using Hybrid Adaptive Control (HAC), were successfully conducted on the manufactured ACP beams and their functionality was further demonstrated. The advantages and disadvantages of ACPs with embedded piezoelectric sensor and actuator patches manufactured employing the abovementioned three wires out techniques are also presented in terms of manufacturing and performance.

No abstract

Adaptive or intelligent structures which have the capability for sensing and responding to their environment promise a novel approach to satisfy the stringent performance requirements of future space missions. Analytical, numerical, and experimental results are employed to verify the performance of piezoelectric stacks and patches as well as to determine the natural frequencies of typical strut and panel structures. A strut model with a piezoelectric stack actuator for axial vibration suppression and a composite beam with surface-mounted piezoelectric patch actuator for lateral vibration suppression are considered to model an active composite strut (ACS) and an active composite panel (ACP), respectively. These ACS and ACP are employed to develop an actuator optimum voltage (OV) for active vibration suppression using modal, harmonic, and transient finite element analyses for a range of frequency encompassing a natural frequency. The ACP model demonstrates that the actuator vibration suppression capability depends on the modal shape and location of the actuator. The OV, in this work, is determined by increasing the level of actuator voltage gradually and generating a vibration with same frequencies as the external vibration but 180 out-of-phase, and observing the increasing level of active vibration suppression until an optimum/threshold actuator voltage is reached. agreements. This work also presents a systematic guideline for the use of piezoelectric stack and monolithic patch smart materials in intelligent structures using the finite element method.KEY WORDS: active vibration suppression, smart composite structures, piezoelectric stacks and patches, finite element analysis, actuator optimum voltage, active composite struts and panels, axial and lateral vibration, actuator location effects.

No abstract