Abstract:

Objective Due to their snug fit, versatile fabric functionalities and other characteristics, seamless warp-knitted products are gaining gradual applications across various fields such as apparel, healthcare, and interior decoration. With the improvement of computer-assisted technology, the demand for online design and real-time simulation of seamless fabrics is becoming increasingly significant. This research mainly explores the knitting principle of seamless warp-knitted fabrics, discusses the special loop structure at the welt stitch locations, and focuses on the simulation research of simple seamless fabrics with double welt stitches.

Method Based on the principle of welt knitting in weft-knitted fabrics, the structure of double-layer welt was analyzed, and a knitting diagram model was established. To deal with the opposite directions of double-layer loops, a top-down grid division and a bottom-up grid division were proposed, and the corresponding loop grid model was established based on the relationship between model points and grid points. Combining the corresponding yarn parameters in the threading model, the three-dimensional loop structure was drawn using WebGL technology.

Results Based on an in-depth study of the loop structure of weft-knitted tubular seamless products a loop geometric model, an upper tuck loop geometric model and a lower welt loop geometric model have been established based on the classic Pierce loop model and the actual shape of the loops. Considering the unique double-layer loop structure of the welt in weft-knitted tubular seamless products two loop mesh models of the same size but opposite directions and a welt loop mesh model were constructed. By combining the loop geometric models, the mathematical relationship between the type value points and the mesh points was constructed to obtain the loop mesh parameters, and the z-direction of the special transverse row loop type value points was adjusted.

An upper welt knitting pattern model, a garment body knitting pattern model, and a lower welt knitting pattern model were established. Through the process, the corresponding loop mesh model was determined using an algorithm, where the direction of loops in the front half of the lower welt and the back half of the upper welt runs from top to bottom, utilizing the welt loop mesh model. For the garment body and the back half of the lower welt and the front half of the upper tuck, the direction of loops runs from bottom to top, using the gridf loop mesh model. By integrating the yarn parameters from the threading model, the three-dimensional loop structure was rendered using WebGL technology.

Examples were presented to demonstrate the simulation effects of typical weft-knitted seamless products in both tubular and flat unfolded forms, clearly showing the interlocking relationship of loops and the double-layer structure characteristics at the welt stitch areas. Examples also showcased the effect of the garment on a human body, with the simulation image of a tube top closely fitting the surface curves of the body, hiding the back welt stitch structure in a way consistent with the actual fabric.

Conclusion The implementation of three-dimensional simulation for seamless warp-knitted products bypasses processes such as machine trials, directly obtaining the finished fabric effect from the pattern design, reducing product development steps, and improving product development efficiency. By comparing the simulation results with the actual fabric, it is demonstrated that using this method to simulate seamless warp-knitted products with double welt stitches is scientifically feasible. It can perform three-dimensional planar, cylindrical, and curved simulations for simple seamless warp-knitted tube tops, laying a foundation for further research into the simulation of complex seamless warp-knitted products.

Key words: welt structure design, loop geometry model, loop grid-based model, weft knitted seamless underwear, three-dimensional structure simulation