计算机辅助设计(CAD)与分析(CAE)无缝融合问题一直制约工业产品的研发效率。等几何分析的提出为CAD/CAE无缝融合问题提供了独特思路，但其在复杂几何形状的精确描述及自适应分析等方面还存在困难。本项目针对复杂薄壁壳体结构，从几何及分析两方面研究其CAD/CAE无缝融合关键问题并基于研究结果开发计算力学软件。主要内容为：针对任意剪裁曲面，研究几何精确、光滑连续的高阶三角形网格生成方法；在此基础上构造等几何三角形壳单元，并结合假设自然应变以及超参单元的思想，解决分析效率与分析精度的矛盾；此外，采用Nitsche方法施加面片间的耦合约束，解决非流形类壳体结构的分析，同时实现局部区域的自由升阶；最后，结合误差分析以及局部细化方法实现h-p型等几何自适应分析。通过这些研究有望建立针对薄壁壳体结构的、高精度与高效的CAD/CAE无缝融合方法，为真正实现工业产品的CAD/CAE无缝融合奠定一些基础。

The level of integration between Computer-Aided Design (CAD) and Computer-Aided Engineering (CAE) determines the overall efficiencies in the design of engineering products. Isogeometric analysis (IGA) utilizes NURBS as basis functions to describe the geometry and physical field which provides a unique pathway to the integration of CAD and CAE. However, IGA still experiences several roadblocks, such as the exact description of complex geometries and the realization of adaptive analysis. In this proposal, we take thin-walled structures as an example and solve the above key issues in the framework of computational geometry and computational mechanics. Additionally, we will develop an in-house software based on the current research project. The main contents of this proposal are summarized as follows: firstly, we develop a mesh generation method that is suitable for complex trimmed surfaces and is geometrically exact and continuous across element boundaries. Secondly, we develop an efficient and accurate triangular shell element based on the assumed natural strain method and the super-parametric concept. Thirdly, we use Nitsche’s method to weakly enforce the coupling constraints between patches. It can be further extended to the coupling of patches meeting at a particular angle or with different element orders. Lastly, we develop an h-p adaptive isogeometric analysis framework by combining the method of error estimation and local refinements. Based on the above research work, a highly efficient and accurate design-through-analysis framework for thin-walled structures can be established which provides a solid foundation for the seamless integration of CAD and CAE.