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 quality of composite preform has great influence on its mechanical properties. Aiming at the problems of difficulty in robot teaching and unstable braiding angle in the process of braiding three-dimensional complex component, a control method of robot is proposed. Firstly, the mandrel is discretized to ensure that the axis of each discrete mandrel is perpendicular to the braiding point plane, and the orientation and direction of the tool center are calculated. Then, the take-up speed of the robot is calculated, so that the self-adjustment of the braiding angle can be realized in the braiding process. The experimental results show that the control method can effectively reduce the braiding angle error of variable cross-section mandrel within 2°, and can improve the quality of composite products in actual production.

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.

The grasping transfer deformation of textile fabrics is the primary problem faced by textile production automation. During the automatic transfer process of textile fabrics, due to its own flexibility, large deformations are brought about, which leads to the problem of overlapping folds before the fabric is formed. In this paper, the end gripper composed of non-contact Bernoulli suction cups is used to adsorb and transfer the textile fabric, and the fluid structure coupling analysis method is used to calculate the adsorption force under different inlet pressures by using the macroscopic continuous model of the end effector adsorbing the fabric. The fluid structure coupling adsorption model is established, and the effects of the number and layout of suction cups and different inlet pressure on the deformation of flexible fabric during clamping are analyzed and studied. The deformation effect of the end effector in the process of transferring fabric is verified by simulation and visual experiment. The results show that the optimal working parameters of the end effector obtained by fluid structure coupling simulation are consistent with the test. When the end effector adopts five suction cups and the air inlet pressure is 0.3 MPa, the deformation is the smallest. This study provides a new method to solve the problem of automatic grasping and transfer of textile fabrics, and provides technical support for improving the automation level of garment industry.

Circular braiding of large-sized and complex irregular structural components is widely used in fields such as aerospace and rail transit. However, existing braiding process design and simulation algorithms lack applicability to mandrels with complex features, such as flanges, concave corners, holes, and hollows, which also have low calculation efficiency in the braiding process simulation. This study first proposes an optimization algorithm for the complex features on the mandrel surface, improving the applicability for the braiding process design of complex and irregular mandrels. Then the mandrel mesh was reconstructed, greatly improving the computational efficiency of the braiding process design process. Finally, a fast iteration method based on the mandrel reconstructed mesh was proposed to achieve the fast calculation of process control parameters, including traction trajectory and traction speed, as well as the prediction of forming quality for the braiding angle and coverage rate. The experiment shows that the algorithm improves the applicability of the multi-braiding angle process and shortens the sampling cycle of braiding process design by more than 60%.

At present, carbon fiber automatic placement technology is mainly applicable to the preform of large and complex components, while the preform of small size and large curvature carbon fiber components mainly relies on manual placement, which has the problems of high labor cost, slow speed, and low repeatability. In order to realize the automatic placement of carbon fiber components with large curvature and small size, this article adopts the carbon fiber patch placement method to make the preforms. By combining the surface subdivision method and the finite element optimization method of carbon fiber patch placement angle, a discrete path planning method of robotic carbon fiber patch is proposed. This method divides the complex surface into surface fragments with similar curvature and normal angle, which can effectively reduce the wrinkles in the process of carbon fiber patch placement and improve the utilization of carbon fiber patch. At the same time, the stiffness optimization design of carbon fiber patch composite preforming is realized by combining the finite element optimization method of placement angle. The helmet surface was selected as the research object of carbon fiber placement path planning, and the path planning of helmet surface placement was carried out, and the simulation tests of helmet placement in different regions and overall placement were compared. It was found that the stiffness of carbon fiber patches placed in different regions of the helmet surface was better than that of the overall placement.