Abstract:

Objective Because of the diversity of loop unit combination, the threading relationship and the pulling effect between different loops, weft knitted fabric structure are prone to deformation, thus achieving a rich fabric appearance. In order to dynamically simulate the deformation process of weft knitted fabric composed of different basic loop structure units, the overall structure of the fabric was controlled and the details of the loop structure were described, so as to further reduce production cost, speed up production efficiency and improve production quality.

Method Interlacing points in the fabrics were represented by a three-dimensional structure model of the loop, as an improvement to the traditional mass-spring model. In order to associate the loop structure model and the mass-spring model with the interlacing point as the link, Non-uniform rational B-splines(NURBS) curves were to simulate the loop centerline, and the mass position through internal force analysis and dynamic solution were constantly updated through. Finally, computer tools were adopted to show the dynamic simulation effect of the associated model.

Results The three-dimensional structure model of the loop and weft plain knitted fabric was established, involving the interlacing points and the type value points, as well as the loop distance, loop height and loop thickness. On this basis, the relationship between the type value points of the loop centerline and the interlacing points were obtained, and the three-dimensional structure model of other loops and composite fabrics through deformation were also achieved.

The mass-spring model unit more suitable for the loop structure unit was established, and the improved mass-spring model was formed. On this basis, the mass-spring model of the corresponding fabric was obtained by changing and adjusting the model unit according to the change of the loop type.

The connection between the loop structure model and the mass-spring model was established by using the interlacing point as the link, and the loop centerline used to describe the geometric path of the loop structure model was generated by fitting based on the principle of NURBS curve inverse calculation problem, as well as the mass positions in the mass-spring system were constantly updated through internal force analysis and dynamic solution.

The dynamic deformation simulation of weft knitted fabric was achieved by using computer tools. An example was given to show the simulation effect of the associated model. As well as an example, the simulation effects of fabric deformation including multiple different types of loops were shown.

Conclusion The loop structure model and mass-spring model of weft knitted fabric were established based on the interlacing point, and the relationship between them was created. The loop centerline simulated by NURBS curve was basically consistent with the geometric structure of the fabric. After reasonable internal force analysis and dynamic solution, the mass positions in the mass-spring model system were constantly updated. The dynamic simulation process of weft knitted fabric was realized.

Key words: interlacing point, loop structure model, mass-spring model, NURBS curve, force analysis, dynamic solution, weft knitted fabric