Week 3

The objective of this projects is to check for the geometrical errors and mesh with the given element Quality criteria
of a "Hood model" using ANSA software.

* Import the "CAD geometry" file into ANSA,the file should be of "STEP(.stp)" or "IGES(.igs)" or "STL(stl)" or "(.ansa)" formats only
because ANSA can only support these formats.

* After importing the CAD geometry we should perform some basic operations like
(a) Set different orientation for top and bottom surfaces.

(b) Check for any issues in the geometry (i.e, execute "geometry cleanup")
(c) Fix all the geometry issues if there are any.

(d) Now perform "Topology" to confirm that all the surfaces are stitched perfectly.
(e) Assign different "PID(part ID)" for different surfaces.

* Now its time for extracting the "Midsurface".There are two methods to obtain the "Midsurface" of any geometry
(1) Traditional Method: Steps to be followed the extract the "Midsurface" using this method is
> Measure the thickness of the geometry and calculate the midpoint of the surface.
> Go to faces tab and select the "offset - faces" and now select the faces for which midsurface has to be extracted and should
enter the midpoint value so that ANSA can generate the midsurface.
> Repeat the above step and should generate the midsurface for the entire geometry.
> There is also a shortcut option for identical geometries i.e, by using "transform" option in the tools section.
> After completing all these steps we need to perform topo to stitch all the midsurfaces.

(2) Auto Midsurfacing: This method can only be used for "closed geometries" therfore before performing this method we need
check the geometry.
To perform this method in we need to select the "Mid.Surface" and "Skin" option in the "Faces" tab and select the surface
for which midsurface has to be extracted.Here we always go for "Skin" option to get the midsurface for any geometry which has
uniforn thickness throughout.

Whenever we use this method for extracting the midsurface of any geometry we will loose the main volume of the geometry
i.e, parent surface will be gone,however we can able to regain it but still in "traditional method" we will be having an option
to retain or to loose the parent surface.

* Hence here i went for the "traditional" offset method to extract the midsurface for the entire geometry.

* Now after getting the midsurface for the entire geometry we need to go for "meshing" process.
> In the "Mesh" module all the 'cons' will be shown in 'green colour' and all the 'hotpoints' will turn from 'pink dots' to 'white spots'
and we can see many 'pink dots' between the hotpoints which are nothing but the 'perimeter elimental values'.
> Before "Meshing" we need give the "Quality Criteria" for the mesh.These "Quality Criteria" will vary for different geometry.
> In "Meshing" we have two types 'Solid Mesh' and 'Shell Mesh'.'Shell Mesh' is basically used for for geometries having uniform
thickness and 'Solid Mesh' is used for 'cast' or 'mould' geometries.

> So now for mesh generation we have various preset options, here i went for 'Best Mesh' option for the entire geometry.
> Before performing the meshing we should check for few things like:
(a) We need to check that all the circles(holes) present in the geometry is parallel to anyone of the closest perimeter because
diamond shaped holes will not give proper meshing therefore we need to "slide" those holes if there are any.
(b) There is also a thumb rule that all the 'holes' should be having 'even' number of 'edges' if there are odd number of edges
it should be realtered.
(c) We should also check for any measurements which are less than the 'minimum length' as per the 'quality criteria' given. If
there are any then in such a case we need to go for "Defeaturing" i.e, compramising on any one feature to save an other
feature, But we should not remove any material from CAD geometry.
> After performing all the above actions now we are good to go for "Meshing". But before start meshing check whether
'Quality Prameteres' and 'Mesh Parameteres' are keyed into the componet (Press F11 to get the quality window).

* After performing the meshing we get the 'check mesh' tab on the screen which will show the type of mesh and the number of
elements available in the mesh.
* To get the 'Quality Prameters' we should enable the "Hidden" mode. In check mesh tab we can see now in total how many
elements are failing.
* Now we should do the mesh adjustment for the elements failing the quality criteria.
* In ANSA we have various mesh improvement tools.
Example: We can go for 'Shell Mesh' tab and use 'Mesh Reconsturction' or we can also use 'Smooth' option to
improve the mesh generated.

* Hence "Mesh generation" is completed.

Conclusion
The "Hood model" is meshed with the given element 'Quality criteria' and the result has been attached bellow.