The Fabric Forming Simulation The Finite Element Method

The cloth modeling technique is much concerned because of itsextensively application to the textile and apparel industries, humananimation, computer games, virtual reality and so on. Many methods aresuggested for modeling cloth. Among them the finite element method (FEM)is the most prospective one, by means of which not only the appearanceof cloth deformation can be obtained, but also the physical details canbe attained, although its expression seems rather profound andcomplicated. The paper is aimed at the FEM technique in simulating clothdrape. The following are the major works in the paper.1. A review of cloth modeling is presented. The parametricdescriptions of the finite rotation are classified based on the study ofpapers about shell elements.2. A new model is proposed that defines the finite rotation by tworelative angles. The finite rotation plays a significant role in thefabric drape, so that the accuracy of its definition is essential. Thenew fini te rotat ion definition is more exact than the classic l inear one,and is simpler than Rodrigues parametric one in geometric exact shelltheory. In addition, it is easy to implement the computation. The modelis not competent in describing the boundary condition of the bendingmoment, but it is not a fatal drawback because fabric cannot generallystand the bending moment.3. According to the geometric nonlinear FE theory, a series of totalLagrangian formulations of degenerated shell element based on the abovefinite rotation definition are derived. 9-node heterosis element and areduced integration technique are applied to the analysis process foreliminating the shear locking. Thus a full and efficient algorithm isproposed.4. A fabric continuum constitutive equation is proposed. It isassumed that the fabric is a matter of continuum, homogeneous,orthogonally anisotropic elastic, and hence the fabric constitutiveequation is formulated. Second, a method of determining the two primaryelastic modules in the constitutive equation from the two respectiveprimary bending moments instead of the two tensile modules is proposed.The influence of Poisson's ratio on the drape shape is considered. Therelevant analysis and calculation show that normal Poisson's ratio inthe range of 0.0--0.5 does not show appreciable effect on fabric drape.5. A computer code is developed to implement the above FE analysis.By using the code, the fabric static drape examples in 2-D or 3-D and somedynamic processes of the fabric drape are presented in the paper. Theresults show that the FEM proposed in the paper is effective.