## 1 Introduction  
The number of technological applications featuring composite materials is constantly increasing. For instance, composites are commonly adopted for manufacturing ship hulls and possible solutions to improve their resistance to slamming damage are currently investigated [1]. Additional examples are machine tools with parallel kinematics architecture [2] and robotic exoskeletons [3], to which the use of composite materials has been recently extended. With reference to automotive applications, carbon fiber reinforced polymer (CFRP) laminates have been used in the past three decades to manufacture body shell components of sports cars, like the hood, since they exhibit a convenient combination of high strength and low weight [4]. Currently, they are under consideration also for possible use in other (mass-market) classes of cars, notwithstanding higher production costs [5; 6]. Indeed, the use of lightweight materials is essential to lower the power consumption, particularly for hybrid and electric vehicles, hence, permitting them to fulfill sustainable mobility policies [4; 5; 7; 8; 9]. Moreover, they may permit to meet more stringent safety requirements in case of impacts [10; 11; 12; 13]. The vehicle body shell components can be particularly critical from the noise vibration and harshness (NVH) standpoint. Indeed, such parts may exhibit undesired elastodynamic effects triggered by several sources, e.g., the engine/driveline operation, vibrations due to the road roughness, aerodynamic loads, and possible impacts with small particles, like raindrops [14; 15; 16; 17]. This may result in a reduced comfort for driver and passengers. Hence, in this perspective, the dynamic response of CFRP panels for automotive applications must be carefully assessed. Numerous advanced materials have been developed to limit the vibration severity of structures and components by increasing their structural damping [18; 19; 20; 21; 22; 23; 24]. While the research is still ongoing, promising results have been obtained [1; 25; 26; 27]. In particular, [PERSON] et al. [1] studied the use of acrylonitrile butadiene styrene (ABS) cells filled with thermoplastic polyurethane (TPU) elastomer to improve the durability of glass fiber reinforced polymer (GFRP) hulls for high-speed boats. [PERSON] et al. [26] investigated the influence of fiber orientation on the damping properties of CFRP cantilever beams featuring a single viscoelastic layer (copolymer of ethylene and acrylic acid--(PEAA)). Similarly, [PERSON] and [PERSON] [27] studied the effects of multiple design parameters (e.g., thickness and position of the viscoelastic layers) on the structural damping of GFRP cantilever beams with the addition of neoprene. [PERSON] et al. [25] investigated the possibility of enhancing the structural damping of laminates with a viscoelastic core by optimizing the core thickness through genetic algorithms. This study focuses on a viscoelastic material that can be embedded and cured inside CFRP laminates, known as SMACWRAP(r), manufactured by SMAC-Montblanc Technologies (Toulon, France). Such material has been preliminarily selected by the industrial partner involved in the research, on the basis of market analysis, supply chain policy, and technical aspects (e.g., stacking and lamination processes). Its effects on the modal parameters of thin carbon/epoxy panels are investigated by means of back-to-back experimental tests on very simple specimens. The main goal is to quantitatively assess its actual damping properties. To the authors best knowledge, whereas the dynamic response of composite sandwich beams with lightweight honeycomb core and SMACWRAP(r) layers has been assessed in [28; 29], no data are available on thin panels. The paper outline is as follows: Section 2 describes the tested specimens, the experimental setup and the signal processing techniques adopted for the analyses; a numerical model implemented to support the analysis of the data is also illustrated.