Research on the surface of multilayer weft knitted fabrics using computer simulation

Purpose - Multilayer weft knitted fabrics possess many advantages, such as strongly stereoscopic patterns, soft handling and adjustable thickness of apparel and home textiles use. However, it is difficult to predict the final visual effects before the productive process because of the three-dimensional (3D) effect caused by the connecting yarn of the fabric. The purpose of this paper is to realize a realistic simulation of the fabric. Design/methodology/approach - The authors applied to the curve and surface model to simulate the knitted fabric, instead of previous single loop model by NURBS. Macro simulation is more suitable for the fabric with the 3D effect because of the quick, real and convenient simulation. This research includes experiments on the structural parameters concerning the regular sag of multilayer weft knitted fabrics, and analysis of parameter data and the simulation process with the aim of realizing a computer simulation of the fabric, especially with a sense of reality. The Digital Elevation Model was also applied to build a simulated 3D model. Findings - To obtain the values for the change rules, different samples were used and the outputs of the model were found to be close to the experimental results. The thickest and thinnest lengths and the changing curves between them were established. Patterned simple multilayer weft knitted fabric could be simulated through the results of the research. It is possible to simulate different real fabrics using their materials and expected effects. The authors are going to improve the model to simulate the complicate large-scale jacquard fabrics in further research. Practical implications - The results will be useful for establishing a computer surface simulation system for stereo perception of fabrics. Originality/value - The authors put forward the concept of surface warpage degree (R). It is an important factor affecting the fabric stereo feeling. The larger the value of R, the stronger the stereo sense of the fabric. It could be applied to most 3D fabric. A thickness difference testing method was proposed to characterize the stereo perception of fabrics. It is possible to simulate different real fabrics quickly without the model of the woven loop.