Adhesive bonding is a suitable joining method to satisfy the increasing industrial demand for carbon fiber-reinforced polymers without the need for a machining process. However, thermoplastic-based carbon fiber-reinforced polymers have small adhesive strength with structural thermoset adhesives. In this study, an ultraviolet irradiation surface treatment was developed to improve the adhesive bonding strength for polyamide-based carbon fiber-reinforced polymer. The type of ultraviolet wavelength, irradiation distance and irradiation time were optimized. Surface treatment with simultaneous UV irradiation of 185 nm and 254 nm wavelength generated unbound N-H stretching that was capable of chemical bonding with epoxy adhesives through a photo-scission reaction of the amide bond of polyamide matrix. Therefore, ultraviolet irradiation treatment improved the wettability and functional groups of the polyamide-based carbon fiber-reinforced polymers for adhesive bonding. As a result, the adhesive strength of the polyamide-based carbon fiber-reinforced polymers was increased by more than 230%.

Three-dimensional printing is a highly promising manufacturing technology that enables easy production of complex shapes. Composite lattice structures are highly efficient, having the advantages of fiber-reinforced composites and the excellent structural performance of lattice configurations. Highly efficient structures can be developed by combining the benefits of 3D printing and composite lattice structures. This study examined the effect of printing path and axial angle in joint areas on the compressive strength of composite lattice unit cells fabricated via continuous fiber 3D printing. Compression tests were conducted to analyze deformation, failure modes, and causes of failure. A finite element model was used to analyze buckling behavior and establish design criteria. Results showed that the printing path significantly influenced failure mode and strength, while a fabrication method without a defect at the joint was important for improving structural performance. Finally, design criteria, in terms of the knockdown factor and in-plane bifurcation buckling behavior, were developed based on experimental and numerical results.

The demand for lightweight and energy-efficient electric motors in electric vehicles, aerospace, and industrial systems has driven the exploration of alternative rotor materials. This study introduces a novel Fe₃Si-enhanced carbon fiber-reinforced polymer (CFRP) composite rotor designed for high-speed synchronous reluctance motor (SynRM) applications. Soft magnetic Fe₃Si microparticles were uniformly integrated into the CFRP matrix using a hand lay-up method with dry particle deposition, resulting in enhanced magnetic permeability and reduced electrical conductivity while preserving structural integrity. The optimized composite rotor core achieved a weight and rotational inertia reduction of 38.12% compared to conventional electrical steel (ES) rotors core, with a reduced density of 4857.95 kg/m³. Furthermore, by strategically reducing the rotor magnetic pole arc angle from 145° to 130°, the lower intrinsic permeability of the composite was effectively compensated. Electromagnetic simulations revealed that the optimized Fe₃Si-enhanced CFRP composite rotor achieves a peak efficiency of 94.0%, closely matching the benchmark ES rotor (95.4%), while suppressing eddy current and core heating due to the discontinuous conductive network of the polymer matrix. These results highlight the potential of Fe₃Si-CFRP composites as lightweight, high-efficiency core materials for next-generation electric machinery.

Wind power is a crucial renewable energy source, but icing on composite wind turbine blades reduces efficiency and durability in cold climates. To address this problem, innovative methods were explored involving steel thread stitching and microwave heating. A glass fiber-reinforced composite with stitched steel thread was fabricated with varying stitching lengths. The effect of microwave heating was investigated using a microwave antenna system constructed in the laboratory. The heating test showed significant temperature rises to 140 °C within 200 seconds, with optimal results at a stitching length of 4.5 cm. The mechanical properties were enhanced, showing a 7.6% increase in flexural strength and a 9.6% increase in impact energy. The deicing test demonstrated complete melting within 25 minutes. Flexural strength showed no decrease after 20 cycles of repeated freezing and thawing. This research offers insights into advanced anti-icing technology for wind energy, promising improved reliability and sustainability.