Abstract:

Objective Weft-knitted stereoscopic jacquard fabric is widely used in home textile such as mattress due to its excellent physical, mechanical, thermal, and moisture comfort properties. The study of bump structure is the foundation for computer simulation of fabrics and crucial for effectively predicting knitting results. The research on design methods and modeling techniques for jacquard fabricsattracted much attention, but the complex structure and challenges in simulating the three-dimensional (3-D) effects of weft-knitted stereoscopic jacquard fabrics pose serious difficulties for researchers, leaving limited references in the field of design and simulation technology for such fabrics. This study focuses on the design of four-color stereoscopic jacquard fabrics.

Method Using the control variable method, an experimental plan was designed to calculate key parameters including total convexity, projection length, front convexity, and back convexity. The investigation emphasized the influence of connection point spacing, weft-lining yarn fineness, and vertical density ratios between front and back sides on these parameters. Fitting surfaces and functions were generated by comprehensively analyzing these three influencing factors. A 3-D bump model was subsequently established based on the derived functions and patterns.

Results The progressive increase in convex values of different connection point shapes as the spacing between connection points gradually increases. Among these shapes, the overall growth trend of the diamond shape was relatively slow, because under the same spacing between connection points, the expandable space size of the weft-lining yarn exhibited the characteristics of scatter > square > diamond. The projection length of the surface was primarily determined by the spacing between the connection points. The projection length of different connection point shapes showed a relatively consistent growth trend with the increase in spacing and exhibied a linear relationship. The data results for different weft-lining fineness were plotted. The results indicated that under the same spacing between connection points, the thicker the lining yarn was the higher the overall trend of the convex value became. In the case of the same expandable space, a thicker lining yarn resulted in a higher content of lining yarn per unit volume. The interaction between the yarns caused them to bend and bulge in the middle of the unconstrained sections, thereby increasing the convex value. For the projection length, the differences among the three sets of results were relatively small, indicating that the influence of the fineness of the weft-lining yarn was minimal and could be neglected. When there was a difference in the longitudinal density between the front and back sides of the fabric, this difference would be projected onto the bump structure, resulting in an asymmetric bump structure, where the ratio of the front convex value to the back convex value was almost consistent with the longitudinal density ratio of the front and back sides. By comprehensively analyzing the influence of the connection point spacing and the fineness of the weft-lining yarns on the bump structure, and combining relevant data, a 3-D fitting surface was generated and the equation is presented.

Conclusion Denser pattern connection areas reduce expandable space. Weft-lining yarn fineness directly affects structural filling volume, while longitudinal density ratios correspond to convexity ratios on both sides. This study calculates connection point spacing across pattern regions based on color information from pattern notations. By incorporating spacing and yarn fineness into the 3-D fitting surface function, front and back convexity values are derived. A 3-D bump model for weft-knitted stereoscopic jacquard fabric is developed using these data. This research elucidates the formation mechanism of such fabrics, establishes a theoretical foundation for fabric simulation, and provides methodological guidance for designing and simulating other bump-effect fabric structures.

Key words: weft-knitting, stereoscopic jacquard, bump parameter, bump structure, 3-D modeling