## 1 Introduction  
The evolution of additive manufacturing (AM), also known as 3D printing, has revolutionized the manufacturing process by enabling the direct creation of components layer by layer from a Computer-Aided Design (CAD) model. This approach not only expedites prototyping but also reduces material waste, rendering it an increasingly competitive option across industries [1]. Moreover, AM's capacity for rapid prototyping accelerates product development cycles, distinguishing it from traditional subtractive manufacturing methods [2]. In the realm of electrical machines, there is a growing interest in exploring new materials propelled by advancements in AM [3, 4, 5]. Soft magnetic materials (SMMs) and soft magnetic composites (SMCs) have emerged as promising candidates for additive manufacturing in electrical machine components, boasting magnetic, thermal, mechanical, and electrical properties conducive to the manufacturing process [6]. Additionally, AM facilitates the utilization of challenging-to-process alloys like soft ferrites, opening up new possibilities for electrical machine applications by leveraging their high electrical resistivity [7]. The versatility of SMCs spans various industrial and technological fields, offering a broad range of applications [8, 9]. Manufacturing SMCs through AM not only enhances the production process but also potentially reduces costs compared to traditional methods [10, 11, 12]. The innovative properties achieved through AM in SMCs allow for diverse applications in sectors like robotics and power electronics [13]. These advancements improve mechanical properties while enhancing the magnetic characteristics of cores, thus increasing magnetic flux densities [14]. In the domain of electrical machines, SMC materials offer several advantages [15], including low eddy current losses and reduced manufacturing costs. Notably, they enable more versatile and efficient designs due to their three-dimensional magnetic characteristics [16; 17]. That is why they have been used as a composite material for different electrical machine elements [18; 19; 20]. This article focuses on investigating the integration of SMC through AM in alternator cores for wind turbines operating under vortex-induced vibration (VIV) [21; 22]. This study fills a gap in research carried out in SMC applied to electrical machines by specifically addressing the integration of SMC in alternator designs tailored for VIV conditions, contributing to the advancement of wind turbine technologies. VIV-based wind turbines, particularly bladeless ones (Figure 1, [23]), exploit VIV to generate electricity, presenting a sustainable alternative to traditional propeller-type turbines. Three prototypes of alternator models have been developed for bladeless wind turbines (BWTs), each featuring cores composed of different materials:  
* Air core or no-core prototype constructed from polyethylene terephthalate glycol-modified (PETG) material [24], exhibiting properties similar to air;
* SMC core prototype manufactured using polylactic acid (PLA) filament infused with carbon steel particles [25], offering medium magnetic conductivity and high electrical resistivity;
* Iron core prototype composed of S275 mild steel [26] and M270-50A silicon steel [27], known for their high magnetic and electrical conductivity properties. The SMC core prototype demonstrates intermediate electrical conductivity properties between air and iron cores, showing enhanced performance relative to air cores while maintaining high electrical resistivity [28; 29]. Although SMC core prototypes have not yet matched the energy generation performance of iron cores, their ability to enhance performance while minimizing losses marks significant progress. Future research may explore heat treatment to optimize SMC properties further [30]. This study presents a comprehensive investigation into the application of SMC materials for manufacturing alternator cores, particularly for bladeless wind turbines operating under VIV.