Conforming Element Mesh for Realistic Textile Composite Micro-Geometry

In recent years, several computer tools, e.g., DFMA, TexGen and WiseTex have been developed to derive realistic yarn-level micro-geometries for textile composites. However, due to numerical errors, the generated micro-geometries by these computer design tools have unavoidably exhibited artificial surface interferences or narrow gaps between yarns. It is therefore problematic to directly input the micro-geometry into a commercial FEM code to generate a conforming element mesh. In this paper, a procedure is developed to generate a conforming FE mesh that matches actual yarn-toyarn and yarn-to-matrix surface inside a textile composite with a complex microgeometry. It improves the accuracy of micro-mechanics analysis. The procedure divides into five steps. Initially, the unit cell domain is discretized into a uniform cuboid finite element mesh and the yarn surface is discretized into triangular plane elements. The second step consists of calculating the intersecting points between yarn surface triangle elements and mesh gridlines in the z-direction. The third step is the removal of numerical error driven artificial surface interferences or narrow gaps between yarns. If the distance between two intersection points from two adjacent yarns is smaller than a specified tolerance, the two adjacent intersecting points are merged to the mid-point. A material type, defined by yarn number, interface or matrix, is assigned to each node. In the fourth step, the initial uniform cuboid finite element mesh is modified so as to match yarn boundaries to the finite element mesh. In the final step, material types/yarn numbers are assigned to each element based on nodal material types. If an element is composed of nodes of two different material types, it is split into two or more elements. As such, a conforming FEM mesh, which matches the element boundary to the yarn-to-yarn or yarn-to-matrix interface, can be generated.