Abstract:

Objective In order to explore the mesh deformation principle in the warp knitted jacquard spacer shoe material fabric, the interaction mechanism of the loops on both sides of the mesh in the warp knitted single needle bed fabric is used to form a three-dimensional spring-mass particle tensile action geometric model between the loops of the surface layer, the bottom layer and the middle spacer layer. The tensile mechanical deformation equation and offset distance between the loops in the jacquard spacer shoe fabric are obtained to improve the three-dimensional (3-D) deformation simulation effect of single jacquard warp knitted double needle bed interval jacquard shoe fabric.

Method Aiming at the mesh area division design of warp knitted jacquard spacer shoe fabric, the jacquard principle of single jacquard comb in fabric forming is studied, and the jacquard artwork is designed and drawn. Using the quadratic Bezier curve to establish the unit loop model, and aiming at the three-dimensional structure of the spacer shoe fabric, the three-dimensional spring-mass model that conforms to the actual fabric structure is constructed, including the shearing spring, structural spring, and bending spring. The offset is worked on by the explicit integration method.

Results The single jacquard comb performs jacquard action on one side of the fabric of the spacer shoe fabric, forming a rich upper appearance through thick, thin and mesh fabric effects. The functional areas of the single jacquard warp knitted spacer vamp are divided (Fig. 1). Using red, white and green to form a single jacquard artwork, it shows fabric structures with different mesh sizes and thicknesses (Fig. 2). Using the natural transition principle of the tangent line of the quadratic Bezier curve, the motion track value of the continuous points of the loop at the tangent line is calculated. A total of 8 shape point control unit loops are adopted to build a three-dimensional geometric model of the loop, which more realistically shows the bending shape of the loop (Fig. 3, Fig. 4). On the basis of the construction principle of the two-dimensional spring-mass model adopted by the conventional warp knitted single needle bed, a three-dimensional spring-mass model based on the double needle bed spacer shoe fabric is established. Three types of spring particle systems are shown, including thick and thin mesh structures formed by spacer wire, chain knitting bottom comb and single jacquard (Fig. 6). According to the influence between spring and masses in the model, the force equation of the loop is established based on Newton's mechanical theorem, and the external force is ignored. The elastic deformation force and damping force between masses are calculated, and the explicit Euler method and midpoint method that are conducive to improving the simulation speed are selected to conduct particle velocity and displacement distance within unit time step. Three improvement measures are put forward for the easily occurring overshoot phenomenon. JavaScript and C# programming language are adopted to program the 3-D simulation of single jacquard warp knitted spacer shoe fabric, and the simulation is compared with the real picture to verify the effectiveness of the mechanical model simulation method.

Conclusion Based on the real state of the fabric, the single jacquard warp knitted shoe fabrics was simulated for deformation, Newton's laws of mechanics were adopted to establish the particle grid system. The influence range of the force of a single loop particle was sorted out, which verified the feasibility of the deformation simulation based on the three-dimensional spring-mass model, and improved the deformation simulation efficiency of the jacquard warp knitted shoe fabrics. The deformation simulation of warp knitted double jacquard spacer shoe fabric and triple jacquard spacer shoe fabric needs further research and realization.

Key words: warp knitted shoe fabric, spacer fabric, circled jacquard, jacquard principle, spring-mass model, three-dimensional simulation