The carriers are moved along the eight-shaped orbit during braiding, which makes the length of dynamic catenary fluctuate in a certain range. With changing the release speed of carriers, the yarn tension is difficult to maintain stability. The varying tension affects the structure and mechanical properties of the products. In this paper, the calculation of geometrical dimension is carried out for common carriers. The aim is to analyze the influence of the pulleys wrapping angle, the spool rotation speed and tension control during braiding. For the same processing task, the kinematics and dynamics models of the radial-direction and axial-direction braiding are established using the Newton–Raphson iterative method. Comparing the simulation results, the fluctuant range and the changing rules of the yarn tension are analyzed, which will provide the theoretical basis for braiding carriers design in the future.

The performance of braided fiber-reinforced composites is determined by the braided structure, so yarn spatial arrangement prediction is a crucial step in the manufacturing process of fiber-reinforced composites. This study aims to predict fabric on arbitrary mandrels based on the yarn interactions, especially for mandrels with flat surfaces. An interaction yarn deposition model is proposed to simulate the process of braiding arbitrary-shaped mandrels. A dynamic deposition model is established at the moment of deposition, and a quasi-static equilibrium equation is added to determine the spatial position of yarn interaction points. Post-processing of positional information is performed to obtain the yarn spatial arrangement on the mandrel’s surface. Experiments were conducted using Zhongfu Shenying 12K T700 carbon yarn and Yunlu Composite 176-carrier radial braiding equipment. The experimental results show that the actual fabric exhibits an S-shaped distribution on the flat surface of the mandrel, matching the predicted results of the model.

The braiding process is an important process for composite fabrication. Aiming at the problem of inner fabric folds and outer fabric sparseness in the bending of the complex geometric mandrel during braiding, a control method for off-center braiding is proposed. The mathematical description of the yarn position in the braiding process under the off-center condition is carried out, solving the differential equation for the convergence length using Euler's method to obtain the convergence length at any moment. The prediction model of the yarn on the mandrel is established to describe the spatial position of the fell point in the coordinate system of the mandrel end face and the coverage rate of the preform is solved by using the coverage rate formula under the off-center condition. The braiding experiments of the two mandrels are carried out to verify the feasibility of the prediction model and the control method. The experimental results show that the prediction model of off-center braiding can ensure that the error between the predicted value and the actual value of the braiding angle is within 5°. At the same time, off-center braiding can reduce the inner coverage rate of the bending mandrel and improve the outer coverage rate, and the error of the coverage rate is controlled within 10%. The errors are mainly caused by neglecting the slip of the yarn on the mandrel and the variation of the fell point due to the yarn interaction.