Purpose

Hexahedral meshing is one of the most important steps in performing an accurate simulation using the finite element analysis (FEA). However, the current hexahedral meshing method in the industry is a nonautomatic and inefficient method, i.e. manually decomposing the model into suitable blocks and obtaining the hexahedral mesh from these blocks by mapping or sweeping algorithms. The purpose of this paper is to propose an almost automatic decomposition algorithm based on the 3D frame field and model features to replace the traditional time-consuming and laborious manual decomposition method.

Design/methodology/approach

The proposed algorithm is based on the 3D frame field and features, where features are used to construct feature-cutting surfaces and the 3D frame field is used to construct singular-cutting surfaces. The feature-cutting surfaces constructed from concave features first reduce the complexity of the model and decompose it into some coarse blocks. Then, an improved 3D frame field algorithm is performed on these coarse blocks to extract the singular structure and construct singular-cutting surfaces to further decompose the coarse blocks. In most modeling examples, the proposed algorithm uses both types of cutting surfaces to decompose models fully automatically. In a few examples with special requirements for hexahedral meshes, the algorithm requires manual input of some user-defined cutting surfaces and constructs different singular-cutting surfaces to ensure the effectiveness of the decomposition.

Findings

Benefiting from the feature decomposition and the 3D frame field algorithm, the output blocks of the proposed algorithm have no inner singular structure and are suitable for the mapping or sweeping algorithm. The introduction of internal constraints makes 3D frame field generation more robust in this paper, and it can automatically correct some invalid 3–5 singular structures. In a few examples with special requirements, the proposed algorithm successfully generates valid blocks even though the singular structure of the model is modified by user-defined cutting surfaces.

Originality/value

The proposed algorithm takes the advantage of feature decomposition and the 3D frame field to generate suitable blocks for a mapping or sweeping algorithm, which saves a lot of simulation time and requires less experience. The user-defined cutting surfaces enable the creation of special hexahedral meshes, which was difficult with previous algorithms. An improved 3D frame field generation method is proposed to correct some invalid singular structures and improve the robustness of the previous methods.

中文翻译：

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基于3D帧域和特征的复杂模型分解算法

目的

六面体网格划分是使用有限元分析 (FEA) 执行精确模拟的最重要步骤之一。然而，目前业界的六面体网格划分方法是一种非自动且低效的方法，即手动将模型分解为合适的块，并通过映射或扫描算法从这些块中获得六面体网格。本文的目的是提出一种基于3D帧场和模型特征的几乎自动的分解算法，以替代传统的费时费力的手动分解方法。

设计/方法论/途径

该算法基于3D帧场和特征，其中特征用于构造特征切割面，3D帧场用于构造奇异切割面。由凹特征构造的特征切割表面首先降低模型的复杂性并将其分解为一些粗块。然后，对这些粗块执行改进的3D帧场算法来提取奇异结构并构造奇异切割面以进一步分解粗块。在大多数建模示例中，所提出的算法使用两种类型的切割表面来完全自动地分解模型。在一些对六面体网格有特殊要求的例子中，算法需要手动输入一些用户定义的切割面并构造不同的奇异切割面以保证分解的有效性。

发现

受益于特征分解和3D帧场算法，该算法的输出块没有内部奇异结构，适合映射或扫描算法。内部约束的引入使得本文的3D帧场生成更加鲁棒，并且可以自动纠正一些无效的3-5奇异结构。在一些有特殊要求的例子中，即使模型的奇异结构被用户定义的切割面修改，所提出的算法也成功地生成了有效的块。

原创性/价值

所提出的算法利用特征分解和3D帧场的优势来生成适合映射或扫描算法的块，这节省了大量的仿真时间并且需要较少的经验。用户定义的切割表面可以创建特殊的六面体网格，这对于以前的算法来说是困难的。提出了一种改进的3D帧场生成方法来纠正一些无效的奇异结构并提高先前方法的鲁棒性。