Aim:- To extract FEA model from CAD model.

1. Checks for geometrical errors of given model.
2. Generating 2D Mesh on surface of model by ortho-tria elements and tia elements.
3. Generating Volume mesh in closed volume by tetra elements.

Aligning mesh distribution uniformly with respect to feature lines.

OBJECTIVE

• FIXING OF GEOMETRICAL ERRORS LIKE Nedle face, triple cons and crack between cons.
• Generating 2D mesh by using ortho-tia elements on curved feature surface and tia elements on flat surface.
• Generating tetra element mesh in closed volume of model.

S.No	Quality Criteria	Value
1	Target/Average length	1
2	Minimum Length	0.5
3	Maximum Length	2

4 Tet collapse 0.2

Procedure

STEP 1: Import CAD geometry in ANSA Window.

STEP 1: Import CAD geometry in ANSA Window. Go to perimeter option in mesh module and change MACROS as well as PERIMETER from 20mm to 1mm to get precise and accurate result. Perform topology to stich neighboring cons.

From checks manager – checks for Geometrical errors

ANSA Checks manager shows total lots errors

we can highlight any of the error site by left-clicking on it, or isolate it on the screen by right-clicking on it and selecting “Show only”.

Needle face error is just a error arises due to coincidence of cons of opposite faces. We can simply delete that needle face from choosing appropriate face ID.

After deleting the needle face id, we can perform topology to stich sharing edges and features lines.

Or we can automatically fix errors by auto fix option.

Tripple cons are also known as triple edge sharing three surfaces,

Select the Face with the left mouse button from its crosshatch. ! Note that when selecting a Face from its crosshatch, this is deleted without any warning. In contrast, when selecting it from its boundary CONS, the Faces Delete List preview window appears for confirmation.

After fixing geometrical errors model is ready for pre-processing process with respect to required Simulation and ANALYSIS.

Step 2:

Now in order to generate 2D Mesh on Surfaces of Model,

We mesh surfaces using SPOT MESH command with the help of both ortho tria and normal tria elements.

• Ortho tria elements capture curved feature surfaces more efficiently then normal tria elements.

• Ortho tria elements requires more computational time then normal tria elements because ortho tria elements needs more variable data to being defined then normal tia elements.

BEFORE MESH GENERATION PROCESS, WE HAVE TO SET QUALITY CRITERIA AND MESH PARAMETER

Shortcut key to open Quality criteria by pressing F11 key.

Meshing Individual part one by one using SPOT Meshing with respect to defined feature lines.

STEP 3:

After 2D Mesh generation on surfaces of all components of model,

We can proceed for VOLUME MESH GENERATION PPROCESS.

First we have to define Volume of component of part from VOLUME MODULE,

Then Enable TEDT COLLAPSE quality criteria=0.2 before volume mesh generation.

After defining Volume we can proceed for tetra rapid mesh generation.

FEA MODEL

REPORT OF FEA MODEL

Learning out come:

• Understand how to generate volume mesh or tetra-hedral mesh.
• Learned the importance of geometrical shape and size of mesh generating elements with respect to geometry and features of model.
• Becoming more efficient and effective in context of fixing quality issues such as Tet collapse.

CONLUSION

Given CAD model checked for geometrical error issue , after fixing geometrical issues we have extracted FEA MODEL from CAD model by 2D mesh generation on surfaces of model and volume mesh generation in defined closed volume space between closed packed surfaces.