Project

MESHING HOOD FOR STRUCTURAL ANALYSIS

AIM:

PROCEDURE FOR GEOMETRY CLEANUP:

The above image shows that there are 213 errors in the geometry when executing the geometry check.
Hence to cleanup the geometry the following tools are used.
TOPO>Faces>Topo- This function automatically creates topological conditions between selected adjacent CONS.
MENUBAR>Utilities>Delete- This function of the Geometry Group can be used to delete various ANSA entities.
TOPO>CONS>Fill Hole- This function fills holes on Faces.
TOPO>CONS>Release- This function releases CONS which have been automatically joined.
TOPO>CONS>Break- This function breaks the selected CONS by inserting Hot Points on locations of discontinuity.
TOPO>Hot Points>Project- This function defines a new Hot Point that lies on a CONS.

The above image represents that the geometry cleanup of the hood model has been completed.

PROCEDURE FOR MIDSURFACE EXTRACTION:

Midsurface extraction can be done both manually or automatically using the tools mentioned below
TOPO>Faces>Offset>Faces- This function offsets selected Faces by a given distance in order to create new Faces.
TOPO>Faces>Mid.Surface>Skin- This function turns the solid description of a thin part into a thin shell description by isolating the outer or inner skin of the solid description.
TOPO>Faces>Mid.Surface>Casting- This completely automatic function is used to create FE shell elements that represent the middle skin of a solid description.
TOPO>Faces>Middle- This function creates a middle Face between two selected Faces.
Here we are extracting the midsurface manually using the offset tool option.
To extract the midsurface using offset tool we shoul know the thickness of the hood model which can be measured using the measure tool.
After measuring we came to know the thickness of hood model as 0.75mm
Now with the offset option we can select the face of the Hood with feature angle option enabled to extract the mid surface.

PROCEDURE FOR HEMMING:

After midplane was generated the inner plane and outer plane of the hood were not in contact with each other. To make them get contacted we are involving a process called Hemming.
HEMMING: Hemming is the process in which the edge is rolled flush to itself.
For the process of Hemming the tools used are
TOPO>CONS>Project- This function projects, as CONS or 3D Curves, a number of selected 3D-curves, CONS, element edges, line elements or Hexa Box edges on a number of selected Faces.
MENUBAR>Utilities>Delete- This function of the Geometry Group can be used to delete various ANSA entities.
TOPO>CONS>Paste- This function pastes two or more CONS segments that lie close to each other, and which usually are boundaries of different Faces.
Here use the above tools to perform hemming, first the upper edge of outer panel has been projected onto the surface of inner panel and then to the surface of outer panel.
Then the outer panel upper surface has been deleted followed by the deletion of projected outer area of the inner panel.
Then using the paste option we will connect the inner panel with the outer panel which results in the triple CONS showing the hemmed area.

The above image shows the hemmed region.
Then we are assigning the PID\'s for inner panel and ouert panel with thickness as 0.75mm and material as mild steel.
The PID for hemmed area has been assigned with thickness as 2*OUTER PANEL THICKNESS + 1*INNER PANEL THICKNESS and material as mild steel.

PROCEDURE FOR MESHING THE MODEL:

To proceed with meshing we have to mention the following quality criteria and mesh lengths.
Here the mesh length is 5 and the quality criteria values are as follows

Now we can mesh the model using the tool MESH>Mesh Generation>Best
After meshing we can see that there are some quality criteria issues which are shown as off elements which can be cleared using the following tools.
Mesh>Elements>Swap- This function rotates the shell edge picked by the user, inside the two shells which have that edge as common.
MESH>Shell Mesh>Reconstruct- This function is a powerful tool for the creation of a high quality surface mesh.
MESH>Shell Mesh>SMOOTH- This function automatically applies Smoothing attributes so as to \'relax\' the mesh on already meshed Macro Areas.
MESH>Elements>Split- This function splits quadrilateral and triangular shell elements into smaller ones.
MESH>Grids>MV Surf- This function moves a selected mesh node on the Macro Area\'s surface, or a perimeter node along the perimeter segment on which it lies.
After using the above mentioned tools we can get rid of the errors and get a finer mesh.

CONCLUSION:

Thus the geometry cleanup, midsurface extraction and meshing of the hood model geometry is completed with accurate results.

Ship work like this
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