Tetra meshing of Intake Manifold using ANSA Pre-processor for Structural Analysis Tool Test 2

Aim : Volume meshing of rear view mirror using ANSA pre-processor.

Objectives :

For the given component, checking for the geometrical errors and meshing it with the given element Quality criteria. Using tetra elements to model the component and and making sure there should not and kinks and dips on the surface of the component.

1) To clean up the topological errors.

2) To clean the geometry using different set of tools.

3) Running diagnostic check.

4) Use of Boolean operations for better visuality of the geometry.

5) Assigning length and Volume meshing the whole geometry.

6) Compressing the geometry after rectifying all the errors in it.

Quality Criteria :

Mesh parameters :

Procedure :

1) To make sure we have a close volume we have to clean up the geometry by identifying the geometrical errors listed under the check manager such as single cons, triple cons, unchecked faces, Collapsed cons, Needle faces, Overlap faces, Cracks and penetration errors which should be avoided to proceed further, if we clean up most of the geometry there will be least possibility of error while meshing.

2) By using Spot mesh tool under Mesh Generation option, mesh macro regions one by one using trias and ortho trias wherever suitable. Ortho trias take lot more time to process than the normal tria so often using of ortho tria wisely is recommended in certain areas of interest. Ortho tria elements must be used on the curved faces over the geometry and the tria elements on the flat surfaces. It will make the processing time lot lesser making it computational inexpensive.

Here by using Spot mesh tool, mesh is generated at the surface.

At flat surfaces tria element type was used and at the curved faces or holes ortho tria element type was used in order to reduce the computational time required to process this type of geometry.

3) Using Number tool under perimeter option for better capturing of mesh elements around it with respect to given element length.

4) Reconstruction is done by using Reconst tool under shell mesh option. By selecting macro area selection type it picks up an element that lies on a macro and ANSA automatically selects all the corresponding macro areas. This type of selection with combination of Spot mesh reconstruction helps to attain the mesh parameters.

5) Quality for Shell mesh is apllied to geometry with target length of 5mm.

6) Getting rid of min length and max length criteria by using MV Free and MV Surf tools under Grid option in the MESH module. Quality for Shell mesh is apllied to geometry with target length of 5mm.

7) Setting up the parameters for volume meshing by inputting the values in Psolid type in Presentation parameters menu.

8) First of all, we have to define the volume by selecting the geometry manually by using Define tool under Volumes option in the VOLUME MESH module. This allows to define the volume inside geometry surface as Psolids elements.

9) Volume list shows us the available volumes to mesh in the geometry which we define earlier as Psolid elements, we have to set the material id and other parameters in the Property id menu with a max growth rate of tetra elements as 1.2. In the below picture we can see that the status here is unmeshed and undefined.

10) To mesh the volume inside the geometry, there are three types of tetra mesh generation algorithms depending upon the objective of the analysis.

Tetra Rapid

The Tetra Rapid algorithm meshes the Volume with Tetra Elements.

Tetra FEM

This function automatically creates a Tetrahedral mesh inside selected Volumes, initially with pyramid elements if the starting surface mesh contains quad elements. It is to be used mainly for structural applications. Volumes to be meshed with this function must have been defined using the Define(Volumes) function.

Tetra CFD

The Tetra CFD algorithm is most suited for geometries of thick volumes, large domains with significant variation in length of the surface mesh (say more than 2 orders of magnitude). Most met in CFD applications.
Activate Tetra CFD and select either one or more already defined volumes or some specific solid elements

In this geomery we are going to used Tetra Rapid algorithm, we can see total number of tetra elements generated in the volume i.e 31375.

11) To satisfy the quality criteria for the volume mesh, we have to get rid of the elements which collapsed tetras and fix them by using MV free and MV Surf tools under Grids in the Mesh module. Here in the below picture tet collapsed elements are fixed by usiing MV Free to meet the quality criteria.

In this below picture we can see that the tet collapse is fixed by moving it certain direction without forming any kinks on the surface of the geometry.

Conclusion : Successfully Tool Test was completed under 3 hours and 30 minutes, and satisfied the given quality criteria and the mesh parameters.