Creating the 3D tetra mesh for the Housing Crankcase and the chassis assembly

OBJECTIVE:

To create a 3D mesh using tetrahedral elements on the housing, crankcase and the chassis assembly models.

PROCEDURE:

Housing-

• Import the STEP file of the housing into the hypermesh.
• It is found that the given model has solid in one of its components. Solids are deleted to have only the surfaces left in the model.

• Some topology cleanup operations are done on the model such that the mesh model will not fail the criterion while capturing the features of the model.

• A 2D mesh is created by using the auto mesh tool with triangles. Target element size is kept at 5mm. The mesh type is kept as TRIAS.
• To convert the obtained 2D tria mesh into the 3D tetra mesh, Tetramesh tool from the 3D panel is used.
• Under tetra mesh parameters, the element quality target is kept as “Tet collapse>0.15”.

• From tetra mesh, 2D tria elements are selected to form the 3D tetra mesh.

Crank case-

• Hypermesh file (.hm) of the crankcase of the engine is opened in the hypermesh.
• The surfaces of the crankcase are found to have some free edges in undesirable positions. The edges are toggled accordingly to clear these types of free edges.

• Some edges are toggled accordingly as per the requirement and model is made ready to mesh.

• A 2D mesh is created by using the auto mesh tool with triangles. Target element size is kept at 6mm. Mesh type is kept as TRIAS.
• Elements density at the edges of the holes is varied accordingly to capture the features of the holes properly.
• To convert the obtained 2D tria mesh into the 3D tetra mesh, Tetramesh tool from the 3D panel is used.
• Under tetra mesh parameters, element quality target is kept as “Tet collapse>0.15”.

• From tetra mesh, 2D tria elements are selected to form the 3D tetra mesh.

Chassis assembly-

• Hypermesh file (.hm) of the chassis assembly is opened in the hypermesh.
• Since the model consists of solids, solids are deleted accordingly and only surfaces are retained.

• Some components are found to have some surfaces which are not attached to the other surfaces of the same component. These types of surfaces are organized accordingly into the separate components (each component is shown below with a different colour)

• As some surfaces are found difficult to mesh accordingly, some modifications are done on the model.
• Some modifications which are done on the model are as shown below.

• Some edges are toggled accordingly such that the elements will not fail accordingly.

• A 2D mesh is created by using the auto mesh tool with triangles. Target element size is kept at 6mm. The mesh type is kept as TRIAS.
• To convert the obtained 2D tria mesh into the 3D tetra mesh, Tetramesh tool from the 3D panel is used.
• Under tetra mesh parameters, the element quality target is kept as “Tet collapse>0.15”.

• From tetra mesh, 2D tria elements are selected to form the 3D tetra mesh.

• In all the above models, from the element checkup (i.e. F10), under 3D, elements failing the tet collapse condition are saved.

• All the elements which are not failing are masked and further element edit is done on the failing elements by increasing the smallest edge of the element such that the elements clear the failing of tet collapse condition. Node with blue selection will move by the distance concerning the green selection node.

RESULT AND CONCLUSION:

• All elements are created according to the criteria.
• Using the tetra mesh parameter option in the 3D panel provides the 3D mesh with less failure of the tet collapse.
• Some features are impossible to be meshed according to the criteria, so small modifications without disturbing the features of the model to obtain the best possible mesh.