# An Overview of Smart Composites for the Aerospace Sector
## 4 Discussion
### Keywords Trends  
The analysis of keywords reveals key areas of focus in the research on smart composites in the aerospace sector. For this purpose, Figure 12 presents the most frequently occurring keywords in the literature. The prominence of \"piezoelectricity\" (271 occurrences) highlights the central role of energy harvesting and self-sensing capabilities in the development of intelligent composite materials [36; 37]. This finding aligns with the growing interest in piezoelectric materials for SHM and adaptive aerospace applications. Piezoelectricity is closely linked to \"nanocomposites\" (207 occurrences), which play a key role in this field due to their exceptional properties. Polymeric piezoelectric nanocomposites have good mechanical flexibility, lower manufacturing cost, suitable output voltage, and fast processing compared to ceramic-based composites [38]. Moreover, the term \"laminated composites\" (176 occurrences) ranks among the most cited terms, reflecting the continued exploration of advanced materials with enhanced mechanical, thermal, and functional properties. These materials can be engineered with tailored properties for enhanced strength, stiffness, and damage tolerance, making them ideal for the complex demands of aerospace structures [39; 40]. A significant research focus is observed on carbon-based nanomaterials, including \"carbon nanotubes\" (134 occurrences) and \"graphene\" (129 occurrences). These materials are widely studied for their exceptional mechanical strength, electrical conductivity, and potential applications in multifunctional aerospace composites. The addition of conductive nanoparticles to a flexible polymer matrix has emerged as a possible alternative to conventional strain gauges, which have limitations in detecting small strain levels and adapting to different surfaces in the aeronautical sector [41]. The \"finite element method\" (133 occurrences) appears frequently, emphasizing its critical significance in the simulation and predictive study of smart composite behavior under varied operational situations [42; 43]. Similarly, \"structural health monitoring\" (129 occurrences) and \"intelligent materials\" (120 occurrences) indicate a strong research focus on real-time damage detection and adaptive material responses in aerospace applications [44; 45]. Lastly, the presence of \"shape memory effect\" (91 occurrences) and \"actuators\" (81 occurrences) proposes a rising interest in self-healing and morphing capabilities for next-generation aerospace structures. Once the most frequent keywords are analyzed, it is necessary to explore the relationship between them. Thus, Figure 13 shows the keyword co-occurrence network, where we can clearly differentiate three clusters: blue, red, and green. The largest and most central cluster (green) is dominated by the term piezoelectricity, emphasizing its fundamental role, as it is in consonance with the most frequent keywords: This cluster is closely linked to laminated composites, finite element method, and structural components, suggesting a strong emphasis on the integration of piezoelectric materials into laminated composite systems and their computational modeling. The other terms  
Figure 12: Most frequent keywords. are related to piezoelectric equations and vibration words, which are the basis for the previous words. Another prominent cluster (blue) revolves around nanocomposites, carbon nanotubes, and reinforcement, indicating the significant research efforts dedicated to enhancing mechanical and functional properties through nanomaterial integration. The association with structural health monitoring (SHM) and intelligent materials suggests that these advanced composites are being explored for self-sensing and damage detection applications.