Active Composite Panel Smart Structures with Simultaneous Precision Positioning and Vibration Control

Description Active Composite Panels (ACPs) are used in form of beams and plates to provide precision positioning, vibration suppression and control, or both at the same time, i.e. simultaneous precision positioning and vibration control. Depending on the applications and needs for ACPs, either surface-mounted or embedded ACPs are needed. While producing ACPs with surface-mounted piezoelectric sensors and actuators has been achieved, effectively embedding these devices within composite structures is a challenge still under research. In addition, to date, no established technique has been introduced to manufacture these ACPs. While some attempts have been made on the development of ACPs with embedded sensors and actuators within fiber glass-based composites, no work has addressed this technology for carbon-based composites, and also with simultaneous vibration suppression and precision positioning capabilities, using techniques we introduced here. It should be noted that carbon fiber-based ACPs with embedded sensors and actuators are electrically conductive and hence are more challenging to produce than their fiber glass-based composite couterparts where fiber glass is not conductive electrically. Electrically conductive fibers such as carbon fibers, if not treated properly during the sensors and actuators embedding manufacturing process, can cause short circuits and destroy the functionality of the sensors and actuators, and hence render the active structure passive.

Researchers at the University of Hawaii Department of Mechanical Engineering have discovered novel methods for manufacturing ACPs with simultaneous precision positioning and vibration control using piezoelectric patches as sensors and actuators embedded within carbon-based composites. The method employs three different techniques. The manufactured ACPs have been tested to demonstrate their successful performance.

In most applications, piezoelectric patches are normally placed close to the surface to maximize their distance from the neutral axis of the panel and to maximize their effectiveness in bending. Therefore, the number of the plies on top of the piezo is minimum and can be cut with small circular cuts to take the wires attached to the piezoelectric patch leads out of the panel with little to no mechanical degradation in the performance of the panel due to the introduction of cut-holes. Therefore in these cases, the wires can be taken out through cut-holes.

Part I (Wires out by Cut-Holes) of the University of Hawaii researchers’ work is on the manufacturing steps for the embedding technique by taking the wires out using the cut-holes technique for the panels where the piezo patch is located close to the surface, and the cut-holes through a few plies on top (and bottom) do not degrade the performance of the composite panels due to the introduction of the cut-holes. If the piezos are located farther away from the panel surfaces such that quite a few panels need to be cut to get the wires out, the cuts may seriously degrade the mechanical performance of the composite panels due to the introduction of the holes through many plies by creating stress concentrations. In this case, the researchers have found ways to remedy this problem. First, the wires can be attached to the piezo, and then taken out through molded-in holes, which is given in Part II (Wires out by Molded-in Holes). It should be mentioned that in using technique I (given in Part I), the attaching of the wires and their later repair are easily done. To remedy the drawbacks with technique I (if too many plies have to be cut and stress concentration is a problem) and technique II (where later repair is not easily possible), Part III (Wires out by Embedding) was developed; it solves all above mentioned problems.

Applications Smart skin in jet fighters Smart blades in helicopters Smart reflector dish for optical and communicational antenna Acoustic control of shells and torpedoes Micro-aerial vehicles Hexapods and tripods Main Advantages Provides simultaneous vibration suppression and precision positioning capabilities The sensors and actuators are embedded and well integrated within the composite structures with carbon fibers that are electrically conductive The possibility of sensor and actuator damages are minimized Introduces various techniques to embed sensors and actuators in carbon-based composites for a variety of applications and needs, with advantages and disadvantages of each technique tabulated.

Type of Offer: Licensing

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