Research And Implement Of Appearance Simulation Technology In Seamless Knitted Fabric

In the traditional craft, the textile design needs to experience such a process many times:tries to weave and revises parameter, and then it may begin the official production. Because weaving needs to spend massive time, manpower, and material, and the fabrics and the pattern design have great variety. Therefore, using the material to weave cannot satisfy the current demand that low cost, quick production.With science technology development, especially the computer technology, the computer graphics or computer-aided design (CAD) are more and more be applied in the textile production. Therefore, with the seamless knitting products as research object, the research about simulating design processes, generating simulation results of fabric and then showing virtual effect of products has very good practical value and practical significance.The present paper takes project "Intelligence Design and Virtual Machining for Seamless Knitted Product" as the background, it was based on the 3D Pierce's loop model, and improved the model from different angles, then built a new 3D loop model that suitable for seamless knitted product. Simultaneously, the paper researched 3D simulation technology (such as fuzzy design or multi-yarn design), so as to enhance realism of the fabric. And then we developed the ASSKF at the platform of VS and OpenGL. The research mainly includes:(1) By analyzing the physical structure of weft knitted fabric and the 3D Pierce's loop model, the paper had bulit a 3D loop model that suitable for seamless knitted product. On the basis of the centre line of a yarn's loop, the loop would be divided into two parts:the arc (such as needle loop or sinker loop) and the the loop pillar. In the 3D loop model, the arc is described by ellipse, and the loop pillar is described by cubic B-spline curve. Because of stress influence while different yarn of real fabric intermeshed, each yarn woule be likely to bend or distort.In the Pierce's loop model, the arc is described by circle and the loop pillar is described by line. Therefore, compared with the Pierce's loop model, the simulation result of 3D loop model is more real.(2) The paper realized seamless fabric appearance simulation of different yarn organization, such as even needle and rib stitch. For even needle, on the basis of the 3D loop model, the simulation effect would be realized by OpenGL. Rib stitch is different with the even needle, it often displays the overlap phenomenon, because a face loop and a back loop would stretch in the depth direction and would compress on crosswise. Therefore the article introduces the compressibility coefficient to describe overlap degree while a face loop and a back loop stretched.(3) The paper researched fuzzy design and multi-yarn design methods. For different types of hairiness, it should use different design methods. Sparse and long feathers can be realized by using B-spline curve, dense and short hairiness can be realized by adding some noises to yarn. And Multi-yarn effects can be simulatated by rotating cross-section. The experimental result indicated that the fabric simulation effect had very big enhancement while increased the feathers effect and multi-yarn effect.(4) The paper realized pattern design of jacquard. Fabric with a jacquard pattern could be viewed as composition of loops which colors are different. Using OpenGL, we had defined different material properties for different loops of fabric. And combined with illumination model, the paper realized jacquard fabric designs.(5) The paper designed and implemented the Appearance Simulation System of Knitted Fabric (ASSKF) to meet the needs of our research project. The system contains such functions:selecting loop model and building it, simulating fabric appearance, fuzzy design or multi-yarn design, saving jacquard design documents and loading it, and so on. Product design personnel can check fabric design effect in real-time. If not satified, he could modify the design scheme. The system can greatly improve efficiency of fabric design, and also shortens design cycle, so it has very good application value.