Week 3

• STEP 1: Study the given assembly of components thoroughly before starting any activities in ANSA for its geometry, criticality and total number of components present and segregate the parts accordingly using "iNot and AND Functions" effectively and assign New PID (Part ID) and material for each component as shown below.

• Component No.1 Initially go ahed with the simple part. There are sub steps involved in each component starting from seperating the parts till the meshing is completed.

1. Image 1: Selected part is performed for "Topology". The part chosen is named as "Center Latch"
2. Image 2: The part is then checked for any errors in Geometry using Checks Manager. Any geometrical erroes in the componenet will be highlighted.
3. Image 3: The errors geneated can be fixed by Right Mouse Button click on the error shown and select "Fix" command.
4. Image 4: Most of the Geometrical errors will be fixed.
5. However it is recommended to manually check for the Topological errors and correct hem by clicking right Mouse button on the error and select show only option. Use "And function" to bring back the corresponding nearest entities/surfaces, select the region where the error is shown, and click on "Release" option under "Cons" Module. upon releasing the cons the nearest faces will torn apart from each other initially. After this again follow the steps mentioned earlier to clear topo errors by selecting "Fix" command upon right click on error. Other option to clear the
6. Image 5: The given Sheet Metal Component is measured for thickness across carious edges as shown and an average is being taken, which in this case it is 1.2mm(Avg)
7. Image 6: The next step is to create the midplane for the half of the thickness of the component, which is 0.6mm in this case. Carefully select the face (recommended to click on "Cross Hatches" on the faces) and assign +/- sign for the entered value by looking at the arrow mark indication. Like wise select all the faces across one single plane. selection of faces in the opposite plane will result in errors like unstiched faces.
8. Image 7: Perform Topo on the midplane created and again check for Topo errors and follow the steps mentioned earlier to eliminate them. Stiched cons will be highlighted in Yellow colour and unstiched cons will be shown in red colour.
9. (Image 8, 9, 10): The cons are stiched using "paste" option in cons module and it looks like a single con in mesh mode after doing it.
10. After completing the Topological operations, the meshing part is being started by entering the Element length in "Length" command in Perimeters module. The chosen length of the element is 5.0 mm.
11. (Image 11, 12,13): Enter the Quality criteria and Mesh parameters as prescribed.
12. (Image 14): The meshing is done carefully by laying out user defined cut across the mid palne so as to ensure smooth mesh flow. Precautions to be taken to avoid opposite Traingular elements, circular pattern following any hole/ hollow geometry. Use "Best" command in Mesh generation module and click on the faces(near to the edges) to be meshed.
13. Image 15,16 and 17 shows that the meshing is completely done for the component with no off's and the association between the CAD geometry and the mesh is defined

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COMPONENET 2 AND 3 LOOKS SIMILAR WITH LEFT HAND AND RIGHT SIDE MIRROR GEOMETRIES (Name given as Latch LH nad Latch RH). THE STEPS FOLLOWED FOR MESHING IS SAME AS EITHER OF THEM

1. Image 1 Indicates that the Topology is beig performed on the component and it turns out that there are no errors.
2. Image 2 shows that the measurememt is taken for mid surface generation and the average thickness is 1.2 mm
3. Images 3 and 4 shows that the offst value for mid surface generaion is entered as -0.6 mm by looking at the arrow mark shown
4. Images 5 and 6 shows that the mid plane is created and it is taken out of the geometry by using iNot and And funtions. The mid plane is then performed Topo so that the unstitched seperate mid surfaces will be stitched back to one single entity. The mid surface so created will be again checked for Geometrical errors using Checks Manager and if there are any, it is rectified by the steps explained earlier
5. Image 7 shows that after the mid surface is created, the mesh element length is being entered in length command in Perimeters Module. After entering this, the mid plane is being carefully observed for any element length criteria is failing for the prescribed element length(5mm).
6. Images 8,10 shows before and 11,13 shows after images of the element length being adjusted by deleting the hotpoint and adjusting the number of hot points using Num+/- command in Perimeters module so as to comply for entered element length.
7. Image 12 shows that the feature of the geometry itself is failing for the element length criteria. In this case, the feature will be subjected to "defeaturing".
8. Image 13 shows that a parametric hot point is being generated at a distance equal to half that of the length between the two cons.
9. Image 14 to 17 shows that the parametric hot points are being inserted across the circumference of the faces with 2 parallel cons. The 2 two parallel cons is being deleted/ defeatured into a singe con to comply with element length.
10. Image 18 and 19 shows before and after instances, that the holes and hollow features of the geometry is being slided using Slide command in parameters module so as to ensure smooth mesh flow.
11. Image 20 shows that the user defined cuts is being used to create a smooth path for the flow of the mesh.
12. Image 21 and 22 shows the Mesh parameters and the Quality criteria credentials is being enterd as prescribed.
13. The selected portion is being partly meshed using Best command in Mesh Generation module (advised to use left mouse click near to edges/cons while selecting faces that needs to be meshed). The agenda is to attain smoothest mesh flow with minimum traingular elements, opposite traingles cicular pattern etc., Generally the mesh need to look like a clean Fish net
14. Images 23,24,25 shows that the mesh generated created an error regarding Jacobian. It can be rectified using Smooth command in Shell Mesh module.
15. Image 26 and 27 shows how an error like aspect ratio can be erased using Delete command in Hot points module.
16. Image 28,29,30 shows how an entire row of offs can be erased by a clicking on Num+/- command in Perimeters module.
17. Image 31 shows completely meshed component with no offs. (Latch LH)
18. Image 32 shows that the association between CAD geometry and the mesh generated. It is done by clicking on Offset command in Elements module and entering "0" for offset value. After this, turning off the Geometry visibility in Features section down, one can visualise only the mesh generated for the entire component. The Mesh so generated is defined as new part ID by clicking on SET PID Command in Faces module under Topo.
19. Image 33 shows other part (Latch RH)

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COMPONENT 4 IS NAMED AS OUTER HOOD AND ACTIVITIES IS AS FOLLOWS:

1. Image 1 shows that the Tological Errors are none.
2. Image 2 shows the thickness of the component as 0.75mm. This coponent is a bit confusing at the edges because this is a single metal sheet, bent to a certain geometry using sheet bending process which initially looks like there is two different thicknesses for this part. The thickness is viewed using iNot nad And functions by selection selected entities just at the edge where the sheet metal is being bent. A cross sectional view reveals that the thickness of the component. The other thicknesses remains at (0.75+/- 0.01) mm across the componenet.
3. Image 3 shows that to generate mid surface, all the faces is selected. Care is taken at the edges where the sheet metal is bent at the corners.
4. Image 4,5,6 shows the mid surgace generated is segregated from the CAD and is given a new part ID. Image 7 shows the element length is chosesn as 5 mm.
5. Image 8 followed by 9 and 10 shows that the feature of the geometry is failing for the element length criteria(Which measures as 0.14mm, which is much less than 5mm Element length ). So that feature needs to be defeatured and is done by inserting hot points using parametric offset at midway across the entire length of the component between the 2 cons failing to meet the length criteria. After the middle con is generated, the other original two parallel original cons is deleted and the same is followed across the entire length of the component to meet element length criteria.
6. After defeaturing the mid surface, delete all the cons using join command except just previously created con at the edge of the entire component. Image 11 and 12 shows the same.
7. Image 13 shows the cuts defined by the user to ensure smooth mesh flow.
8. In the next step, the Mesh parameters and Quality Criteria is being entered as prescribed and proceeded for meshing part using Best command in Mesh Generation module.
9. Image 14,15,16,17 shows an example how triangular elements are eliminated using a con introduced between them by using Cut command in Macros module and later the neighbouring elements should be smoothened to ensure no flow pattern/waviness is present using Smooth command in Shell mesh module.
10. Image 18 and 19 shows an example on how two opposite traingular elements can be erased by introducing a user defined cut in between.
11. Image 20 and 21 shows an example how 2 opposite Triangular elements cand be merged to a rectangular elements by clicking on Num+/- command in Perimeters module. Right mouse click on the con will reduce the hot point number and left mouse click will increase the number of hot points.
12. Image 22 and 23 shows an example on how 2 opposite trianglular elements are erased.
13. Image 24 and 25 shows an example on how elements like these can be smoothened just by introducing a user defined cut in between as shown.
14. Image 26 and 27 shows an example on how deleting unneeded hot point can erase an error.
15. Image 28 and 29 shows an example on how a cluster of traingular elements can be erased in one instance by introducing an user defined Cut as shown.
16. Image 30 shows completely meshed component. The mesh so created should be given New Part ID and should be saved.

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COMPONENT 5 IS NAMED AS INNER HOOD AND THE STEPS ARE AS FOLLOWS

1. Image 1,2,3 shows how the topological errors can be erased by selection of all errors and right click on mouse button and click on fix to fix the issues. But the actual manual methodology of eliminating Geometrical errors in being explained in 1st component.
2. Image 4,5,6 shows the Automatic Mid surface generation because there are various faces and contours across the geometry. So it would be time consuming to go with manually selecting the each and every faces to be meshed and the chances of missing a small face which is hard to visualize will create topological errors in the midsurface created. The Red colour resembles one of the two faces across the entire geometry and same goes with green colour. The blue colour is however the thickness variable in Z-Axis across this sheet metal component, which is 0.75+/-0.01mm across the component. The offset parameter is entered accordingly in image 7
3. In Image 8, the Mid surface generated is being checked for Geometrical errors in Checks Manager and should be procedeed further only if no errors exist.
4. Image 9 shows the element length is entered as 5mm.
5. Image 9 shows defeaturing of the geometry in some of the similar areas as described earlier in other components.
6. All the cons were deleted initially and user defined cuts were introduced across the geometry to ensure smooth mesh flow and following are the common commands used to proceed with mesh.

• "Mark/un" Command to mark the hot points module so that it won't change its position during meshing.
• "Project" command in Hot points module to copy the hot points to any neighbouring cons and "parametric" to enter the values to specific point from the start point.
• "Num+/-" command in Perimeters module to increase(with left mouse click) and decrease(with right mouse click).
• "Slide" in Perimeters module to rotate holes/hollow regions so as to allign it for smooth mesh flow.
• "Cut" command in Macros module (left mouse click) to insert new con and (right mouse click) to erase.
• "Join" command in Macros module (left mouse click) to remove the inserted con. Note that "Keep" option to be checked in options list at the bottom corner of the ANSA GUI.
• "Best" command in Mesh Generation module to mesh the user chosen surface.
• "Improve" and "Smooth" commands in Shell Mesh module to improvise the mesh generated.
• "Split" command in Elements module. Left mouse click on the con will insert the cons in a rhombus pattern with edges box checked in and right mouse click on the con will Swap the con to a neighbouring element.
• "Swap" function is used to interchange neighbouring elements with each other.

The final image shows the final meshed component wit zero offs and zero unmeshed areas.

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