In this paper, a method for designing a two-dimensional (2D) braiding machine to braid preforms with special-shaped cross-sections is proposed. By means of splicing the running tracks of a traditional flat braiding machine’s carriers, the 2D braiding machine can produce various structures with special-shaped cross-sections such as thin-walled cross-shaped, H-shaped, U-shaped, and T-shaped cross-sections, greatly expanding the application of 2D braiding. This paper studies the collisions of carriers after track splicing, dividing the collision problem into two categories, and putting forward a method to analyze whether the carriers collide. The judging method can not only verify whether there are collisions between carriers but also guide designers to change the layout of horn gears to avoid collisions. The mapping relation between the common arrangements of the carriers and the number of slots of the horn gears is also summarized, providing a theoretical basis for a future customized 2D braiding machine according to the practical needs.

The preforms of three-dimensional (3D) braided composites have a monolithic structure that is braided with high-performance fibers using 3D braiding technology. Compared with traditional laminate composites, braided composites are widely favored because of their superior overall performance and mechanical properties. The capability of fabricating various yarn structures with a flexible 3D rotary braiding method, however, has not been systematically investigated, especially for a variable-section braiding structure. In accordance with the principles of braiding technology and the characteristics of a 3D braiding structure, in this study, we examined a braiding technology for the production of 3D variably shaped cross-section fabric, focusing on three key factors: the topology design of tracks, the arrangement of carriers, and the matrix algorithm of the braiding of variably shaped cross sections. We calculated new kind of structural synthesis approach to a 3D braiding track for a variable section based on the carrier arrangement characteristic method and completed the entire braiding scheme of the variable cross section. In addition, this approach represents an important step toward a simplified understanding of the carrier motion and the operator-independent operation of a 3D rotary braiding machine.

Two-unit cells developed to predict the effective thermal conductivities of four-directional carbon/carbon composites with the finite element method are proposed in this paper. The smaller-size unit cell is formulated from the larger-size unit cell by two 180° rotational transformations. The temperature boundary conditions corresponding to the two-unit cells are derived, and the validity is verified by the temperature and heat flux distributions at specific positions of the larger-size unit cell and the smaller-size unit cell. The thermal conductivities of the carbon fiber bundles and carbon fiber rods are measured firstly. Then, combined with the properties of the matrix, the effective thermal conductivities of the four-directional carbon/carbon composites are numerically predicted. The results in transverse direction predicted by the larger-size unit cell and the smaller-size unit cell are both higher than experimental values, which are 5.8 to 6.2% and 7.3 to 8.2%, respectively. In longitudinal direction, the calculated thermal conductivities of the larger-size unit cell and the smaller-size unit cell are 6.8% and 6.2% higher than the experimental results, respectively. In addition, carbon fiber rods with different diameters are set to clarify the influence on the effective thermal conductivities of the four-directional carbon/carbon composites.

This paper describes the splicing of an 8 × 8 484 cross-break track, based on the carrier arrangement characteristics (CAC) method for track splicing technology. The arrangement period of the carrier (T) in the track is obtained in order to discern which slot has a carrier in a period and which one does not. Six basic types of track unit are deconstructed, and a mathematical model is established to determine the possible state of the carrier in each slot of the track unit. Finally, the specific pattern of the carrier arrangement in the 484 cross-break track unit is obtained and verified using a three-dimensional (3D) rotary braiding machine with a square track disc. This provides a reference for solving the carrier arrangement of a 3D square rotary braiding machine.

Stereo parking equipment has become an important means to solve the problem of parking difficulties, so it is necessary to study the planning of stereo parking equipment. This paper proposes an evaluation model for parking equipment planning and design, and verifies the feasibility of the model through an example. First, obtain the surface information of the planned area through object-oriented technology, and then complete the design layout of the area that can accommodate the most parking spaces according to the plan information map of the study area. Next, calculate the number of parking spaces required for each building in the area, and the number of available parking spaces within the maximum acceptable time for each building. Finally, compare the two to design the number and location of parking equipment. This method can quickly and accurately obtain the ground plane information map of the study area, while ensuring the capacity of parking spaces to meet the needs of users, it also improves the rationality and suitability of the planning and layout of stereo parking equipment, which can effectively guide the planning and construction of urban parking equipment.