In this paper, the interlaminar shear strength (ILSS) of laminated composites with thermal bonding layers was measured by short beam shear (SBS) method to evaluate the effect of different contents of thermal bonding layers on the properties of laminated composites. It is characterized by using a certain interlacing law to lay the thermal bonding fibers into a regular mesh layer. By placing the thermal bonding layers between carbon fabrics, the two adjacent carbon fabrics can be bonded together by the thermal bonding layers through hot-press actions to help achieve overall integrity of preform with complex structure. This kind of special thermal bonding layers is prepared using thermoplastic nylon fiber (TPNF) with a low melting point. The thermal bonding layers were prepared with five different contents (2.08%, 4.17%, 6.25%, 8.33% and 10.42%) of TPNF. The resin transfer molding (RTM) process was used to prepare the laminated composites with thermal bonding layers. And the laminated composites without TPNF (0%) were also prepared as control group. Furthermore, the SBS test was conducted at room temperature. The experimental results show that the content of TPNF has a certain effect on the interlaminar properties of laminated composites, and 2.08% of TPNF increased the ILSS, indicating that proper addition of thermal bonding layer can not only help to achieve overall integrity of complex geometry shape preform, but also improve interlaminar properties of composites.

Ply splicing design is a crucial technology to realize the precise manufacturing of woven composite components with various complex shapes. This paper reports two ways of splicing, inter-layer splicing, and in-plane splicing. Two factors affecting the tensile properties of carbon fiber/epoxy laminated woven composites with ply splicing are discussed, including the number of continuous fabric layers on the surface and in-plane splicing spacing. The deterioration of the composites induced during the tensile test is characterized by acoustic emission and digital image correlation. The results reveal that the damage of the laminated woven composites with ply splicing occurs mainly at the butt jointing location and leads to fracture failure. Ply splicing has little effect on the tensile modulus of the composites. The tensile modulus is slightly reduced between 2% and 5%. But ply splicing has a more significant effect on its tensile strength. The total number of continuous fabric layers at the splice position approximately determines the strength retention ratio. The more the number of continuous fabric layers on the surface are, the higher the tensile strength of the composites. When the number of continuous fabric layers on the surface is three layers, the tensile strength retention ratio reaches 69%. The larger the splicing spacing is, the better the tensile properties of the composites. When the splicing spacing is increased to 30 mm, the tensile strength retention ratio reaches 77%.

Based on the problem of shape-preserving property of complex geometry shape preform, a kind of new fabric with thermal bonding layers was designed in our work. From the apparent view, it can be seen that the carbon cloth was attached with a layer of thermal bonding layer structure. The two adjacent carbon fabrics can be bonded together by the thermal bonding layers through hot press actions. Because of the particular characteristics, this type of fabrics can help to achieve the overall integrity of complex geometry shape preform. This kind of particular fabric with thermal bonding layers was prepared by 3D weaving process using carbon fiber and thermoplastic nylon fiber. To evaluate the effect of thermal bonding layers on shape-preserving property of fabric, the fabrics were prepared with five different contents of thermoplastic nylon fiber. And the pure carbon cloth without thermoplastic nylon fiber was also prepared as control group. The shape-preserving property of fabric was evaluated by single-wing springback test and fabric peeling test in the 0° and 90° direction. The experimental results show that the effect on shape-preserving property of fabric enhanced with the increase of contents of thermoplastic nylon fiber, and the shape-preserving property of fabric was more significant in 0° direction compared with 90° direction.