This presentation was made at the 2019 NAFEMS World Congress in Quebec Canada

Resource Abstract

This paper describes how we generate FEM mesh from CAD models, either surface models or solid models, automatically. It is essential to use high-quality mesh for simulations since the result may vary depending on the input FEM mesh model. To assure the quality of simulation results, it is common to create FEM mesh models according to specific meshing rules.



However, it usually takes enormous time and effort to modify FEM mesh model to maintain the quality of mesh following all of meshing rules if it is done manually. Generating mesh automatically using CAD surface shape recognition technique helps to drastically cut down time and effort spent on FEM mesh modeling process.



CAD shape recognition algorithm that we used is for both surface-only CAD models and solid models. From the input CAD models, we analyze characteristics of each face and face continuity. The characteristics of face includes size, radius, and shape. For solid CAD models, we also analyze thickness to assure solid mesh quality.



FEM mesh generation algorithm works based on this shape recognition database. This CAD shape recognition procedure needs to be extended when the meshing rules are set for specific features or complicated shapes. To satisfy these advanced meshing rules, we use shape data such as cross-sectional shape and face combination.



We also use CAD shape recognition data for quality error mesh modification process. It is important to maintain CAD shape representation as much as possible when simplify or ignore input CAD shapes to assure mesh quality.



With FEM mesh generation using CAD surface shape recognition technique in this paper, we achieved to:

- Clean up bad CAD shapes such as small holes, non-abutting lines, and self-intersections.

- Generate high-quality mesh according to mesh rules.

- Generate mesh fast.

- Modify error mesh based on shape recognition data.

- Maintain CAD shape representation as much as possible.



For automobile engine assembly models, we accomplished to automatically create FEM models for NVH analysis according to meshing rules without error using this technique. This means that the automatically created FEM models did not require any manual modification work such as mesh quality improvement and mesh shape representation modification after using our technique. We also confirmed that generating a FEM cylinder head model in required mesh pattern for durability analysis was automatically done in about 1.5 hours without mesh quality error.