一种面向3D打印的“弱平衡”轻量化建模方法

随着3D打印的发展,模型的轻量化建模已成为该领域的一个研究热点。提出一种"弱平衡"轻量化建模方案来生成3D打印模型的内部填充结构。该方案能够根据结构分析自动生成内部密度变化的填充。该方法主要包括三个步骤:利用基于截面结构分析的方法来分析模型的应力分布及薄弱部分;利用一种混合的网格偏置技术向内部偏置模型,生成壳体模型。根据模型的应力分布,提出一种改进的泊松圆盘采样技术在偏置模型表面生成连续的密度分布点,在应力大的区域,点的分布密集,而在应力较小的区域,点的分布较稀疏;提出一种"弱平衡"八叉树技术对采样点进行空间划分,利用体心立方结构及Delaunay 3D算法将偏置模型生成四面体网格模型。在该四面体网格模型中,单元四面体的体积从外部到内部渐变,且在物体薄弱部分填充密度较大。这些单元四面体被用来直接生成"框架-结点"结构。所提出的"弱平衡"轻量化方案允许根据应力分析在模型不同的部分生成不同密度的填充,从而取得全局优化的填充。

A Weak-balance Light-weighting Modeling Method for 3D Printed Objects

With the development of additive manufacturing (3D printing), light-weighting of 3D models is one of the research hotspots today. A weak-balance light-weighting modeling method to generate internal filling structures for 3D printed objects is presented. This scheme can generate varying internal filled density according to structural analysis of 3D models automatically. This method involves three necessary steps. A cross-sectional structural analysis method is used to analyze the stress distribution and weak parts of a 3D object. A hybrid offsetting algorithm is used to offset the model by a given distance. Based on the stress analysis, a continuous density distribution of points on the offsetting mesh is generated using an improved Poisson-disk sampling. Parts where exist high stress, sampling points are dense, otherwise sampling points are sparse. The weakly balanced octree technique, body centered cubic (BCC) and Delaunay 3D algorithm are used to transfer the offsetting model into a tetrahedral model which is “internal grading” and “weak density”. Then tetrahedrons of the tetrahedral model are used to generate the “Frame-Node” structure. The weak-balance light-weighting scheme areallows us to implement different filled density for different parts based on stress analysis, which can achieve global optimization.