*4.2.4.1. By maypole braiding method*

Maypole braiding method requires two yarns sets such as warp (axial) and braider yarns. Axial yarns are fixed and the braiders intertwine with the axial yarns by moving back and forth radially about circumferential paths. Uozumi [93] produced a 3D circular braided fabric by using multi-reciprocal braiding process. This process relies on the 2D circular triaxial braiding essentials and requires two sets of yarns such as ±bias (braider) and warp (axial) yarns. Thick fabrics with different cross sections including structural joint, end-fitting and flange tube were made by over-braiding [9]. Multi-reciprocal braiding process is shown in Figure 33.

Brookstein et al. [94] developed a tubular fabric that consists of braiders (±bias yarns) and warp (axial) yarns. Braiders intertwined around each axial yarn so that they lock each individual axial yarn in its place. This intertwining forms a helix structure. In the process, a horn-gear type machine bed is arranged cylindrically so that the axial and braider carrier are positioned inside the diameter of the cylinder. In this way, adding layers and ensuring the structure compactness becomes easy. A horn gear mechanism governs the movement of the braider yarns. They travel in a pre-defined path about the axial yarns to form the fabric (Figure 34). A take-up unit removes the preform from the weaving zone. This process is well suited to

**Figure 33.** Schematic view of 3D circular axial braiding based on maypole method [9].

produce thick tubular structures and also has the potential for other geometries with a mandrel. Similar 3D axial braiding machine based on maypole method was also developed by Japan as shown in Figure 34 [95].

**Figure 34.** (a) 3D circular braiding by maypole method [94] (b) another type 3D axial braiding machine from Japan [95].
