Researchers from Donghua University in China and the University of British Columbia in Vancouver have introduced a novel design methodology for 3D rotary braiding machines, offering a significant step forward in the production of complex geometric textile composites. Their work details a programmable design approach based on circle-cutting and combination strategies that enhances the ability to create 3D braided composites with intricate shapes.
3D braided composites are highly valued for their exceptional mechanical properties, such as high delamination resistance, energy absorption and damage tolerance. These materials are widely used in the aerospace, automotive and medical industries, and their applications are expanding into emerging fields such as triboelectric nanogenerators and sensors. However, conventional 3D braiding machines have limitations in designing composites with complex geometries. The new methodology proposed in this study addresses this challenge by introducing a flexible and programmable design approach for 3D rotary braiding machines.
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The core of this innovation lies in the average cutting circle method, which involves dividing a complete circle into equal sectors and making incisions to create horn gears. By varying the number of incisions and combining different cut-circles, a diverse range of 3D rotary braiders can be designed. The researchers derived a parametric equation for the braider plate, demonstrating that a combination strategy involving two cut-circles is feasible, while integrating three cut-circles simultaneously isn’t viable for a single machine.
To validate their design strategy, the researchers constructed an automatic 6-3 type 3D braiding machine. This machine successfully produced complex preforms with uniform structures using a variety of materials, including carbon fibre, polyimide fibre and spandex. The prototype machine featured 19 cut-circles controlled by independent stepping motors, accommodating up to 67 carriers within a 1.6-square-metre area. The braiding process was programmed to alternate the rotation of cut-circles with different numbers of incisions, ensuring smooth and collision-free operation.
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The study also compared different types of 3D rotary braiders, highlighting that the new designs can accommodate more carriers than existing models. For instance, the 6-4 type braider can move four carriers between two adjacent horn gears, doubling the capacity of the 6-2 type. This increased carrier capacity allows for the production of more complex patterns and structures.
One of the key applications demonstrated in the study was the design of a complex bifurcated pipe using the 6-3 type rotary braider. This type of structure, commonly used in artificial blood vessels, is challenging to produce with traditional braiding methods. The new braider, however, can seamlessly transition between different configurations, enabling the effective production of bifurcated fabric.
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The mechanical properties of the resulting composites were also evaluated. A hexagonal composite produced using the new braiding technique exhibited a tensile strength of 778.5 MPa and an elongation modulus of 34.7 GPa. Although the elongation modulus was lower than that of traditional composites, the material maintained favourable mechanical properties, demonstrating the potential of the new braiding method for creating high-performance composites.
This new cutting circle method provides a practical solution for advancing the development of complex geometric textile composites. However, challenges remain in scaling up the technology, particularly in managing the power consumption of individually controlled motor systems. Future work will focus on enhancing the control schemes and software design for these advanced braiding machines.
The research has been published in Engineering.