MESHING HOOD FOR STRUCTURAL ANANLYSIS USING ANSA

MESHING HOOD FOR STRUCTURAL ANALYSIS USING ANSA

OBJECTIVE:

• Extract a mid plane and hem hood parts without any topological errors
• Generate a clean mesh of hood within the specified parameters

DESCRIPTION:

Hood is generally made up of MS sheet metal of uniform thickness of 0.75mm which consists of overlapping edges. To perform mesh in this model is quite cumbersome. Here is the process of Hemming which enables the sheet metal parts to free from overlappings to enable easy mesh. In this process, we project overlapped edge on to both inner and outer panel and delete the overlapped surfaces and isolate the hemming region and give the thickness of 2.25mm using formula [2O+I] where O-outer panel and I-inner panel.

METHODOLOGY:

• Topology clean up and midplane extraction
• Hemming of parts
• Assigning PID\'s and MIDs
• Meshing with specified parameters
• Rectifying mesh errors

Topology clean up and mid plane extraction:

• Hood consists of outer panel and Inner Panel isolate each at a time and perform operations
• Clean the geometry using regural topo commands avoid cracks and triple cons.
• After geometry clean up extract mid plane using Mid surface or Offset.
• Extract mid planes of both inner and outer planes.
• Now again check for any topo errors in mid planes.

Hemming of parts:

• Isolate only mid planes and perform hemming
• Hem is the overlapped area along edges of both planes
• project the overlapped edges onto both inner and outer planes
• Delete the hem up to fillet area and the inner plane which is under hem
• Then paste both planes results in a triple con which is acceptable in this case

Assigning PID\'s and MIDs:

• Assign PIDs for individual planes and for hem region alone.
• PID\'s are assigned by set PID command and selecting respective parts,below are the set of PID\'s s.
• MIDs are material IDs these are assigned while assigning PIDs by choosing MID in PID dialog box.
• Set thickness for planes as 0.75mm and hem region as 2.25mm while assigning PIDs.

Meshing with specified parameters:

• Switch to Mesh mode -> set length-> select whole planes and hem -> give length as 5mm-> ok.
• Then set Quality Criteria-> shells->assign respective values specified for mesh-> apply-> ok.
• Then Mesh generation-> Best-> visible.
• There will be a lot of mesh errors so hit Reconstruct->select whole mesh->middle button-> edges->middle button.

• After Reconstruct there are again some errors there are rectified by walking over each and every error and rectifying it.
• some might get fix by reconstructing the mesh in error identified parts alone
• some migth get fix by altering the geometries
• some remain hard to fix, these can be fixed by using certain tools
  • cut
  • swap
  • split
  • paste
  • join
  • MVsurf
  • MVfree
  • Elements-> Delete and New
• Finally, with the combination of all these, we get rid of all errors

RESULTS:

• The model is checked under geometry check and surface check after correcting errors the check results are as follow:

CONCLUSION:

• Extracted midplanes without any topological errors thus ensuring absolute geometry check.
• Hemming has been done with atmost concern to avoid topological and mesh errors in furthur operations.
• Rectified mesh errors and grip over mesh quality has resulted with hand full play of commands.

Drive link for HOOD:

https://drive.google.com/open?id=11-pAazVQ2WZRNXCuT_YHQeBhBHaVlILv