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Prof. Dr. Yordan Kyosev, TexMind UG, Mönchengladbach, Germany
Braiding is a process of interlacement of yarns at certain angle to the product axis used for production of shoe laces, decorative tapes, ropes, medical stents and other linear articles [1]. In the recent time the same process is used for covering (overbrading) of light cores with high performance fibers, as a step for the production of textile composites. (Over)-braided carbon fibers profiles are used for instance for the production of composite parts for the aerospace, automotive and other industries, for which the low weight or the complex hollow form are very important [2].
The most people do not notice many braid products during their daily usage. For example the shoe laces, the elastic tapes in the sport clothing or the heat insulation in the cars. Actually every modern car contains more than 1500 meter of braids [3] as heat insulation, oil pressure sleeves, electrical cable shielding, flexible high current cable between the battery and starter motor, etc. All these products and the braided ropes and the braided medical stents are designed and optimized very precisely before the serial production takes part.
The possibility to create virtual twins of the products and to evaluate their properties bevor the start of production process can speed up the time for designing significantly and can reduce the costs of the products. The braiding machines are not so flexible in the selection of the number of yarns per product, as in the case of weaving and knitting machines are. Once built, a braiding machine with for instance 32 carriers, cannot be used for braids with 30, 28 or 26 carriers. For this reason the virtual design of the braided products and their evaluation at the early stage of designing has much more meaning as for the other textiles products.
Virtual products can be created in different ways. Some researchers simulate the complete braiding process using Finite Element Method software [4] or using kinematic approaches [5]. These tools require users, who can handle with complex simulation software (for Finite Element Method), or are not able to represent the classical braids (for the kinematic approach).
The geometrical models are much simpler than the above mentioned methods. In the case of classical tubular and flat braids the geometrical models can provide virtual models with enough good accuracy for rapid modelling and evaluation and because of this these methods are implemented in the software package “TexMind Braider” is based.
Figure 1a represents created virtual rope. It can be used for evaluation of the approximate diameter of the rope, its weight per meter and the required yarn length, for checking the colour arrangement and the view in different braiding angles. Additionally, the single filaments of the strands can be visualized as shown on Figure 1b, so that their twist direction can be determined as well. Calculation of the tensile behavior and the strength for the rope are included currently only in their basic form. More precise simulation of the tensile behavior is a under development.
Figure 2 represents a virtual braided medical stent. The geometry of this product can be exported to STL format for 3D printing and evaluation or in various formats for CAD or FEM programs for simulations.
For the situations where the braids have complex form, for example solid profiles, sealings, etc., the emulation of the braiding machine and the motion of the carriers can be done easily by using the software “TexMind Braiding Machine Configurator”. It calculates and visualizes the motion of the carriers and thus can be used to check if the configuration will produce crash of the carriers or not. If the selected carrier arrangement can be used on the designed machine (figure 3a), then the braided product will be generated and shown as a 3D picture (figure 3b and c).
The current Version of the Configurator does not compute the contact process between the yarns, in order to allow rapid evaluation of the product, even bevor the braid and the machine for its production are built.
In this way the CAD Packages “TexMind Braider” and “TexMind Braiding Machine Configurator” support the development of braided products, by helping the engineers with a possibility for a rapid evaluation of the braids and their machines.
