Trimming of 3D solid finite element meshes using parametric surfaces: Application to sheet metal forming

In this paper we present a methodology for trimming 3D solid finite element meshes using a non-uniform rational B-spline (NURBS) surfaces representation. The algorithms applied in the identification of the spatial position of the finite element (FE) nodes and elements relative to the trimming surface are described, as well as, the explanation of the correction methods adopted to geometrically rearrange the trimmed elements. Three different strategies are proposed to adjust, with greater or lesser accuracy, the trimmed FE mesh to the trimming surface. The first consists only of an element elimination strategy, while the other two are based on a nodal stretching strategy, aiming for more accurate adjustment of the finite elements boundary to the trimming surface. Finally, to highlight the capabilities of the developed program, a mesh generation example is given by trimming a mesh with the shape of a blank automotive panel.