三维主动脉瓣膜的体参数化构建
Constructing Volumetric Parametrization Model of 3D Aortic Valve

主动脉瓣膜是由复杂曲面构成的，其几何模型需要高阶的自由曲面表示，其物理场需要网格离散表示，二者存在表示格式不兼容的问题，针对该问题，本文提出一种可用于等几何分析的三维主动脉瓣膜体参数化构建方法。首先，从CT图像中分割出主动脉瓣膜区域并转化为点云数据，将点云数据由十二条切割线分割为六个表面区域；其次，使用样条曲面构建每个表面区域的几何表达，由表面样条曲面经过体布尔和运算生成体参数化模型；最后，由点云数据的Hu (Hounsfield Unit)值信息构建多材料分布的参数化模型。实例表明该方法能用更少自由度表达复杂曲面并储存多材料分布信息，基于体参数化模型实现主动脉瓣膜几何表达与材料分布相耦合，完成计算机辅助设计CAD与计算机辅助工程CAE集成。
The aortic valve is composed of complex surfaces. Its geometric model requires high-order free-form surface representation, and its physical field requires mesh discrete representation. There is an incompatible representation format between the two. To address this problem, this paper proposes a three-dimensional aortic valve body parametric construction method that can be used for isogeometric analysis. First, the aortic valve area is segmented from the CT image and converted into point cloud data. The point cloud data is segmented into six surface areas by twelve cutting lines; secondly, the spline surface is used to construct the geometric expression of each surface area, and the surface spline surface is used to generate a volume parametric model through volume Boolean and operation; finally, the Hu (Hounsfield Unit) value information of the point cloud data is used to construct a multi-material distribution parametric model. Examples show that this method can express complex surfaces with fewer degrees of freedom and store multi-material distribution information. Based on the volume parametric model, the aortic valve geometric expression and material distribution are coupled, and the integration of computer-aided design CAD and computer-aided engineering CAE is completed.