Week 4

AIM:

To create better mesh quality by applying given quality criteria parameters on the given plastic model and assigning proper thickness.

OBJECTIVE:

Make proper geometry cleanup before going to extract the midsurfaces of different components in the given model, After that go for meshing by setting given quality criteria parameters and correct the failed elements, By using quality criteria tools. Finaly assign the thickness to all the components in the given model.

GIVEN MODEL:

*Given plastic model is varying thickness along the component and it has ribs and teeth with different thickness show in Fig(1) below.

Fig(1).

PROCEDURE:

1.The Ansa software supports the generic CAD formats i.e( STEP,IGES,STL).

2.Import the cad geometry which is in any above format in ansa by using open option by, selecting the File >> open.

3.Observe the geometry carefully to notice that geometry have any symmetrical faces, thriple cons, single cons etc.

4.To identify above mentioned geometric issues we have to use Checks option in that click on Geometry to open the Geometry checks manager tab as shown in below Fig(2).

Fig(2).

5.Above Fig(2) shows that the geometry does not have any geometrical errors. since it has executed upto 100 percentage.

6.Once geometry checks completed then extract the 'mid surface' either using midsurface option or 'offset' option.

7.Mid-surface option is used mostly in sheet metal operations because they have constant thickness throught the component.

8.Offset option used in both constant thickness and varying thickness components, but mostly used in plastic components due to varying thickness.

9.In this model since it is a plastic component which is varying thickness along the component. I used offset,middle,multi middle option to extract the mid-surface of component by, Selecting the TOPO >> Faces >> offet (or) middle.

Fig(3).

10.If we observe the above Fig(3) we can find all the ribs and different components all those components are have different thickness.

11.Let's see how can we create the mid-surface for threads .

12.Extracting mid-surface for teeth and threads are a bit difficult i.e here first create a curve between two cons on the rib and then extend the curve to base mid surface then create a new face using New option in faces.

13.Below Fig(4) and Fig(5) shows how the mid-surface of the threads can be generted.

*Creating mid-curve for threads Fig(4). Extending the mid-curves to base mid-surface Fig(5).

14.After creating all the mid-surfaces for the parts in the component, then start meshing.

15.After completing the geometry cleanup we can create the Quality criteria parametre file and mesh parametre file as shown in Fig(6) and Fig(7).

Quality criteria parameters Fig(6). Mesh parameters Fig(7).

16.Before start the mesh assign the length value equal to average element length in parameters panel in topo i.e TOPO >> parameters >> length.

17.Perform the mesh using the Best option in Mesh Generation option i.e Mesh >> Mesh Generation >> Best. Perform the mesh operations and eliminate the off element by using Reconstruct,smooth ,split and different options.

Fig(8).

18.In above Fig(8) we can see clearly the unmeshed surfaces,off elements ,trias,quads,tria percentage etc.

19.Once after completing the mesh on the component make sure there are no off elements and unmeshed surfaces as shown in below Fig(9).

Fig(9).

20.The complete mesh on the plastic model in Fig(8) with having zero off elements and unmesh surfaces.

21.Similarly i performed same procedure for other components in the given Model.

22.To assign varies thickness we have to create varies PID's and apply those components to particular PID.

THINGS LEARNT IN THIS CHALLENGE

1.Creating mid-surface for thickness varying components like ribs,teeth,threads etc.

2.removing off elements an unmeshed surfaces.

CONCLUSION

1.Taking Mid-surafce for thickness varying components using mid-surfaace option i.e( auto mid-surface ) wiil lead to create bad mid-surface.

2.Manual mid-surface is the best method to generate the mid-surface for such components to get more approximate results.

RESULTS

*The Final Results shown in below Fig (10) Different color component shows that they belongs to different PID's.

Fig(10).