Week 4 - 2D Meshing for Sheet Metal

2D MESHING FOR SHEET METAL: 

OBJECTIVE: 

the objective of this challenge is to obtain a preprocessing by using ansa software.

preprocessing consist of a geometry cleanup ,mid surface , quality creteria and meshing.

the generated meshing is based on the following creteria.

PROCEDURE:

CAD MODEL: CCB cad model

step 1: Import the geometry in ANSA software.

step 2: the geometry ready for geometry cleanup

step 3: after importing cad model into ansa, there might be a error because of format conversion from other file to ansa .

there might be a missing surface and it is very important to clear the all errors before meshing, the errors may be 

• single cone
• triple cone
• crack 
• unchecked surface

some of the steps to follow to clear the geometrical errors

•  faces>topo - with the help of this all the single cone error gets cleared
• tools>check>geometry - to ideantify the location of the error in the geometry
• tools>check> geometry>right clk>fix - most of the error gets resolved
• tools >check>geometry> right clk> show only - to show the exact location of the error and resolved manually.
• faces> orient - to avoid the oerientation issue , all the faces are oriented similarly

step 4: Extracting the mid surface:

after the geometry cleanup the geometry ready for mid surfacing and keep them in separate property id .

topo>faces>offset>select face >t/2>ask >middle mouse clk>set new propert id > assign thickness > ok> double clk on the propert id > mid surface gets generated.

i measure thickness at different location , i got parts with different thickness. selecting a parts one by one based on the thickness from property panel and performing a mid surface.

my property panel:

• MS_1.6 - T=1.6
• MS_1.2 - T=1.2
• MS_2   - T=2
• MS_2.5  -T=2.5

after extracted the mid surface check the error once , if it is there need to clean by check geometry.

the geometry has to be free from the error before going to meshing.

                         

            

step 5: Mesh generation :

the next step is to create a meshing. 

the mesh parameters need to assigned by using utilities>mesh parameters> it asks target length, maximum length and minimum length.

after that quality creteria has to be assigned by using utilities>quality creteria tab> assigne values or use short cut F11.

for mesh the perimeter should be same length ( L=5mm)- for that perimeter> length> select faces by window selection > L =5mm > for both perimeters and macros .

the perimeter length should be same.

start mesh the component one by one by using the best mesh for that go to mesh >mesh generation >best mesh.

the best mesh gives the meshing in the best possible manner.

after that check the quality creteria , quality check has done when only in the hidden mode .

resolving the quality issues by using commands like reconstruct,smooth,split ,swap,paste etc.

shell mesh > reconstruct - it helps to avoid the rotating quads.

try to kept trias as low as possible.

the following things needs to considered while handling the trias.

• No opposite trias
• No trias on features
• No back to back trias touching each other
• No trias touching the edges

for that we are using commands like split ,swap ,paste .

finally we got the better meshing based on the quality creteria.

CONCLUSION:

in this challenge we have done the mid surface and 2d meshing based on the quality creteria in ANSA.