关键词: 热传递, 毛羽, 拉毛针织面料, 有限元仿真, 线圈模型

Abstract: The surface hairiness of raised yarn knitted fabrics can not only affect the appearance style and fashion sense of the fabric, but also affect the heat transfer performance of the fabric. Therefore, relevant fabric manufacturers have designed and developed knitted fabrics with different degrees of raising yarn to meet the different fashion and functional needs of consumers. However, there is currently a lack of sufficient theoretical basis to elaborate on the relationship between hairiness and the heat transfer performance of raised yarn knitted fabrics. At the same time, traditional experimental testing methods have the disadvantages of being time-consuming, laborious, and requiring a large number of samples, which is difficult to fully and accurately explain this relationship. Therefore, it is necessary to use new methods to study the heat transfer performance of hairiness and raised yarn knitted fabrics, in order to guide the design and development of raised yarn knitted fabrics.
To explore the influence of hairiness on the heat transfer performance of raised yarn knitted fabrics, we propose a method to predict the heat transfer performance of raised yarn knitted fabrics. A knitted loop-hairiness layer model is established, and based on this, finite element simulation analysis is carried out on the heat transfer performance of raised yarn knitted fabrics. The effectiveness of the model is verified through experimental tests. Firstly, we measured four knitted fabrics with different degrees of raising yarn to obtain the geometric structural parameters of the fabrics. In SolidWorks professional modeling software, the knitted loop structure of the fabric was established based on Pierce's two-dimensional loop model theory. On the basis of this structure, the hairiness layer of the fabric was established using ANSYS DesignModeler. Then, we meshed the models of the four fabrics, and used finite element analysis software ANSYS Fluent to set boundary conditions according to the simulation environment, and performed iterative calculations to obtain the temperature distribution cloud images of the four fabric models. Finally, we tested the knitted fabrics with different degrees of raising yarn through experiments, and compared the simulation results with the experimental test results to verify the effectiveness of the model.
The research results show that the correlation coefficient between the simulated thermal resistance value and the experimental thermal resistance value of the raised yarn knitted fabric is close to 0.993, and the maximum difference is less than 17.7%, indicating that the finite element model has certain feasibility. The higher the surface hairiness density of the raised yarn knitted fabric, the greater the thermal resistance of the fabric. However, when the hairiness density reaches a certain range, the thermal resistance of the fabric changes slightly.

Key words: heat transfer, hair, brushed knitted fabrics, finite element simulation, the loop model