EXTRACTING MID SURFACE 2D MESHING OF A IP SUBSTRATE USING ANSA

EXTRACTING MID SURFACE 2D MESHING OF A IP SUBSTRATE USING ANSA

OBJECTIVE

• To create 2D mesh for IP substrate component with given element quality criteria and to assign midsurface thickness to the shell element using ansa.

METHODOLOGY:

1. GEOMETRY CLEAN UP
2. MIDSURFACE EXTRACTION
3. MESHING AS PER CRITERIA
4. ASSIGNING THICKNESS PROPERTY

1.GEOMETRY CLEANUP

• Open the IP substrate component ansa file.
• set the perimeter length and macros to 4mm under mesh module.
• give topo for the entire component and check usually for any abnormal faces.
• check the geometry for errors with check manager and correct the errors like triple cons,cracked faces,single cons.
• auto -fix the geometry.
• some of errors are manually removed.

2.MIDSURFACE EXTRACTION

• The given model is complex and has variable thickness.hence different mid surface extraction methods are adopted.

• Midsurface can be extracted from different methods,in this IP substrate model used manual midsurface extraction method because the auto mid extraction method not gives better midsurface as compare to manual mid mehod for complicated models.
• Commands used to create midsurface are

1. offset
2. middle
3. extend

1. OFFSET--This function offsets selected faces by a given distance in order to create new faces.
2. MIDDLE--This function creates a middle face between two selected faces.the new face will lie on a surface that is created between the surface of the two selected surface.
   
3. EXTEND--This function extends faces according to specified surface distance or they until reach targeted face.

3.QUALITY CRITERIA

• quality as to be assigned as per given quality criteria.The given element quality condition is entered into the quality criteria tab and it is saved.

S.No	Quality Criteria	Value
1	Target/Average length	4
2	Minimum Length	2
3	Maximum Length	6
4	Aspect	3
5	Warpage	15
6	Skewness	45
7	Jacobian	0.7
8	Minimum Quad Angle	45
9	Maximum Quad Angle	135
10	Minimum Tria Angle	30
11	Maximum Tria Angle	120
10	Tria Percentage	15

• JACOBIAN--Is a measure of the deviation of a given element from an ideally shaped element.the jacobian value ranges from -1.0 to 1.0,where 1.0 represents aperfectly shaped element.

• WARPAGE--Is defined as angle between normals to two planes formed by splitting the quad element along diagonals.max.angle out of the two possiblities is reported as warp.

• ASPECT RATIO--Is the ratio maximum edge length to the minimum edge length of an element.the ideal value of the aspect ratio is 1.however the aspect rato of less then 5 is accepted.

• SKEWNESS--Is the angular measure of element quality with respect to the angles of ideal.

4.MESHING AS PER QUALITY CRITERIA

Meshing can be generated using different mesh methods.

1. SPOT MESH
2. BEST MESH
3. BATCH MESH

a.SPOT MESH--This function automatically meshes Macro and FE shell mesh areas using a special meshing method for Macro-Areas that have \'weld spot\' nodes on their surface.

The Spot Mesh algorithm gives better results than the free meshing method and creates the optimum number of shell elements, taking into account the element type already selected and the defined meshing parameters.

b.BEST MESH--This function automatically meshes Macro Areas using all alternative meshing algorithms and keeps only the mesh of highest quality according to QCHECK. The Best function may be applied to selected unmeshed Macros, or to all visible Macros according to the chosen option (Selected or Visible respectively). The \'Re-Generate\' option applied to selected Macro Areas where, firstly, erases existing mesh, if any, and secondly meshes them using the Best meshing algorithm. The \'Options\' configuration feature enables the user to determine the meshing algorithms to be used. The resulting shell elements are of first or second order shell elements according to the status of the 2nd Ord flag.

C.BATCH MESH--batch mesh generation is a well organized way of meshing complex components.the mesh flow in batch meshing is perfect.feature capturing is perfectly done in batch meshing.

FOR PROPER MESH FLOW THE METHODS USED FOR IMPROVING MESH FLOW ARE

• RECONSTRUCT--Re-construction function is a powerful tool for the creation of a high quality surface mesh. It examines a given mesh and performs re-meshing to correct problematic areas and optimize the overall quality of the mesh according to the mesh parameters. For Geometry Mesh (Macro Areas) all modifications are made on the underlying CAD surface.
• SPLIT--This function splits quadrilateral and triangular shell elements into smaller ones. Element splitting is performed between selected nodes and/or inserted nodes along selected element edges. The function can be applied on individual or groups of shell elements in order to improve the mesh orientation, reduce the number of triangles, or refine locally or globally the mesh of a part. Refer to ANSA User\'s Guide for a detailed description of the use of the function.
• SWAP--The Mesh>Elements>Swap function rotates the shell edge picked by the user, inside the two shells which have that edge as common.

5.ASSIGNING THICKNESS PROPERTY

• while performing midsurface extraction ,midsurface parts and properties are set to auto create options.
• in the propert tab the mid surface are selected and renamed according to their names
• the thicKness values of each part are entered.