固定网格技术避免了沿结构边界繁琐的网格划分过程，在复杂几何结构分析时具有很大优势。建模精度和分析精度是采用固定网格进行结构分析的两大难题。文中针对固定网格分析中的建模精度问题，提出了一种由CAD模型至分析模型的快速转换方法，首先将CAD模型采用边界描述，然后通过射线交点法来区分固定网格中单元的属性，并借助四叉树/八叉树技术实现对边界网格的细分。最后采用加权B样条有限胞元法来保证CAD模型在固定网格中的分析精度。本文建立了一种由结构CAD模型至固定网格仿真分析的设计框架，数值算例表明了该方法的有效性。
The fixed grid technique avoids the complicated meshing process along the boundary of the structure, showing great advantages in the analysis of complex geometric structure. Modeling accuracy and analysis accuracy are two major problems in structural analysis using the fixed grid. To enhance the modeling accuracy in the fixed grid, a fast transformation method from the CAD model to the analytic model is proposed. Firstly, the CAD model is described by the boundary representation, and then the ray intersection method is developed to distinguish the elements in the fixed grid. The boundary elements are subdivided by the quatree/octree technique. Finally, the weighted B-spline finite cell method is used to guarantee the analysis accuracy of the CAD model. In this paper, a new design flow from the structural CAD model to simulation analysis in the fixed grid is established. Numerical examples demonstrate the validity and efficiency of the proposed method.
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