## 1 Introduction  
In aerospace systems, the interaction between rigid and flexible dynamics generally leads to relevant elastic disturbances, often compromising the desired performance and target requirements [1; 2; 3]. Rigid-flexible coupled models are required to properly represent and study such complex and multidisciplinary phenomena, as in the case of aircraft wings, helicopter blades, and flexible satellites. At the same time, innovative materials are currently studied to reduce mass and enhance mechanical and thermal properties [4], often leading to lightweight components and structures, but also to increased overall flexibility. Among these materials, thermoplastic composites have demonstrated their appeal as a technological solution for aerospace applications in a wide range of temperatures, offering several advantages over more traditional materials such as thermosetting composites and metal alloys [5]. Several applications have already implemented carbon-reinforced thermoplastics, and a relevant body of research is currently proposing additional uses. [PERSON] et al. [6] designed and analyzed a trainer aircraft's wing by replacing the aluminum and epoxy-carbon fiber composites with carbon fiber-reinforced poly-ether-ether-ketone (CF-PEEK) composites, showing that the latter had lower deformations and higher frequencies, while exhibiting stress levels comparable with traditional materials. [PERSON] et al. [7] proposed an innovative thermoplastic composite fastener based on CF-PEEK, with a higher specific joint strength than titanium, scalable by varying the carbon fiber mass fraction. [PERSON] et al. [8] presented an experimental investigation into the permeability of CF-PEEK for cryogenic storage tanks for aerospace applications, and demonstrated that--in the absence of damages--the permeability remains essentially constant for different ranges of thickness and temperature. [PERSON] et al. [9] proposed and realized a primary CF-PEEK structure for a sounding rocket mission. [PERSON] et al. [10] investigated the effect of debris impact damage on a space robotic arm-cylinder shell realized in carbon-reinforced PEEK. Concerning the automotive sector, composite innovative materials are proposed for future mobility as in the work from [PERSON] et al. [11], for carbon-based accumulators from [PERSON] et al. [12], and for lightweight wheels from [PERSON] et al. [13]. Overall, the diffusion of lightweight and flexible composite materials has paved the way to explore and address challenges related to damping performance in several applications. Aside from researching technological manufacturing solutions to improve damping factors for composite materials [14], new approaches are needed to ensure satisfactory dynamic behavior beyond traditional strategies [15]. Active Vibration Control (AVC) emerges as one of the most promising solutions in this regard. Several approaches can be applied to this problem, ranging from the type of actuators/sensors to be implemented on passive structures, to the control algorithm. Specifically, smart materials such as piezoelectric actuators/sensors are considered some of the most mature devices that can be installed on aerospace structures to suppress unwanted flexible oscillations [16; 17; 18]. This is particularly relevant in the space sector, including those applications demanding satellites to be compliant to high precision pointing accuracy and structural stability [19]. Indeed, flexible appendages equipped to spacecraft are highly impacted by the rigid/flexible dynamics interaction phenomenon, particularly while performing agile maneuvers (i.e., fast re-orientations) [20]. To choose a relevant case study in this regard, and to keep generality of application, a solar panel structure is selected in this paper to evaluate the vibration suppression performance of a piezo-based AVC system on a CF-PEEK material.