Ichiro Nishigaki

A flexible automatic hexahedral mesh generation by boundary-fit method

A general-purpose automatic hexahedral mesh generation system for FEA (Finite Element Analysis) was developed, based on a shape recognition technique and the boundary-fit method. In this system, a solid model is analyzed and decomposed into single-connected sub-models. Then, other sub-models topologically identical to the original ones are constructed using only orthogonal angles. Cubes are used to construct intermediate models, which reassemble these, and finally, hexahedral meshes are generated by mapping the cubes back onto the original solid model. In order to make the automatic system more flexible and friendly to the user, this system also has the capability to interact with the user to modify the intermediate models used in the system to improve the quality of generated mesh, or to help the system to circumvent various topological difficulties.

High-Quality and Property Controlled Finite Element Mesh Generation From Triangular Meshes using the Multiresolution Technique

In this paper, we propose a new triangular finite element mesh generation scheme from various kinds of triangular meshes using the multiresolution technique. The proposed scheme consists of two methods: a mesh quality improvement method and a mesh property control method. The basic strategy of these methods is a combination of the mesh subdivision and simplification. Given mesh is first subdivided to obtain enough degree of freedom for a property change, then by simplification using edge collapse for the resulting mesh to change the mesh properties, we can easily improve and control the mesh properties required for finite element analysis. DOI: 10.1115/1.2052847

Automatic Hexahedral Mesh Generation with Feature Line Extraction

Abstarct. An improved method using feature line extraction is described for automatically generating hexahedral meshes for complex geometric models that automate the normally interactive operations (such as model editing). Testing showed that the time taken for these interactive operations was significantly reduced, making it possible to quickly generate hexahedral meshes with sufficient quality for complex models. Application of this method to mechanical part models showed that it shortened the time to generate a mesh in about 10% the time required with the previous method.

Mesh simplification and adaptive LOD for finite element mesh generation

In this paper, we propose a new triangular finite element mesh generation method based on simplification of high-density mesh and adaptive level-of detail (LOD) methods for efficient CAE. Mesh simplification evaluating mesh properties is applied to control the mesh properties required for FE mesh, such as the number of triangular elements, element shape quality and size while keeping the specified approximation tolerance. Adaptive LOD methods based on vertex hierarchy according to curvature and region of interest, and global LOD method preserving density distributions are also proposed in order to construct a more appropriate FE mesh. These methods enable efficient generation of FE meshes with appropriate properties for analysis from a high-density mesh. Finally, the effectiveness of our approach is shown through evaluations of the FE meshes for practical use.

Notice of Retraction Automatic generation of weld models for railway rolling stock

The air-conditioning equipment and other structures attached to railway rolling stock are plate objects joined by a spot or an intermittent welding. The finite element (FE) modeling of such plate objects is very time-consuming due to the large number of spot and intermittent welds that must be modeled. We developed automatic weld modeling technology, with the aim of reducing the procedures for FE modeling. Applied to a test cover model, the technology reduced the modeling time to 1/3. And FE stress analysis showed that the result accorded to an experimental data within an error range of 11%.

Multiresolution Finite Element Mesh Generation

Effective and robust automatic generation methods of finite element mesh of product model are required for CAE. Although many researches for them have been done, robust mesh generation for complex solid shapes with small features and flexible mesh property control are still difficult in current finite element meshers. In this paper, we propose a new method for automatic finite element mesh generation of a product model based on multiresolution representation of high-density mesh which are stably generated by existing finite element meshers. In our approach, geometrical and topological mesh properties required for FEA can be controlled using user-specified parameters, and mesh elements corresponding to the solid model elements used for setting the analysis conditions are preserved on the simplified meshes. Using our method, robust finite element mesh generation where the mesh property is controllable could be realized.Copyright

A Multiresolution Mesh Processing System for Efficient CAE

With the progress of 3D scanning technology and storing mesh data to 3D model databases, the use of the meshes obtained by scanning and DB querying in CAE have been strongly required in addition to those obtained from traditional meshing of solid models. In our research, we developed a multiresolution mesh processing system for triangular meshes to realize CAE using various kinds of meshes. Our system consists of three functions based on the multiresolution techniques: mesh quality improvement, mesh properties control, and local mesh density control. This paper describes these functions including the extension for tetrahedral meshes, and also shows their effective use in the CAE

Development of a Zooming Analysis System using 3-dimentional Geometric Model.

This paper describes a zooming analysis system that uses a three-dimentional geometric model. A finite element analysis (FEA) using a zooming technique is needed for the estimatation of stresses in a very small area. However, it takes a long time to make an FEA mesh model and set the analysis conditions of any part of the model. We have developed a technique that automatically creates the FEA mesh model and sets the analysis conditions of any part of the model. In this system, a user inputs a geometry and analysis conditions of the entire model as well as the geometry of any part of the model and carries out a whole-model analysis and a detailed analysis of the target part. Employing this zooming technique significantly reduces the analysis time.