Automatic finite element mesh generation and correction from 3D image data

Abstract

In the framework of the ContraCancrum project, automatic generation of an accurate finite element mesh is necessary for minimum user-interaction. The interest on automatic volume meshing for finite element (FE) has grown more popular since the apparition of microfocus CT (μCT) due to its high resolution, allowing assessment of mechanical behavior at a high precision. However, the basic meshing approach of generating one hexahedron per voxel produces jagged edges. The Laplacian operator can be used to smooth the generated mesh, but this method produces mesh shrinkage and volume changes. In this paper an automatic meshing and smoothing algorithm for FE meshes from 3D image data is presented. The method includes a regularization step to assure good element's shape based on a quality measure. The algorithm introduces a novel technique to combine hexahedron and prism elements in order to increase the degree of mesh smoothness while maintaining good quality of elements. The smoothing method is based on low-pass signal filtering using transfer functions approximated by Chebyshev polynomials, resulting in a fast and computationally efficient method being extended here for FE meshes. The smoothing process was evaluated on various data based on the quality of the elements after smoothing, and stress distribution.