Extraction of mid surface and generate the mesh for hood using hypermesh

Objective-To extract the mid surface for the given model and mesh the model according to the given quality criteria and apply thickness.

Tools used to perform the above objective are:

• Quick edit:The Quick Edit tools can be utilized with the option to force the immediate re-meshing of surfaces after a topology change (set in the Meshing Options panel accessible from the Preferences menu\'s, Meshing Options sub-menu; the setting is labeled topology revision on that panel.
• Auto clean up:Use the Autocleanup panel to perform automatic geometry cleanup and prepare your model for meshing based on the parameters set in the Batchmesher criteria file.
• mid surfacing:Use the Midsurface panel to extract the midsurface representation of a solid part or to generate a finite element shell representation of a solid geometry.
• Auto mesh:Use the Automesh panel to generate a mesh of plate elements using surface geometry or existing shell elements to define the mesh area.
• element clean up:Use the Element Cleanup panel to perform automatic cleanup of 2D elements based on the element quality criteria from the Quality Index panel or a separate criteria file.
• quality index:Use the Quality Index panel to calculate a single value to represent the quality of the displayed shell (2D) model.
• smooth:Smooth panel to improve element quality in a surface-based mesh or a mesh of solid elements using one or more algorithms that adjust node positions to moderate sharp variations in size or quality in adjacent elements.
• rebuild:Use the Rebuild Mesh panel to streamline the process of remeshing existing meshes to generate a new mesh with good quality and flow.
• split:Use the Split panel to split plates or solid elements. In addition, hexa elements can also be split using a technique that moves progressively through a row of elements in the model.
• edit element:Use the Edit Element panel to hand build, combine, split, or modify elements.
• replace:Use the Replace panel to relocate one node to the position of another or manually equivalence two nodes.
• organise:Use the Organize panel to (re)organize your database by copying or moving data (entities) among collectors, includes, or parts.
• edges:Use the Organize panel to (re)organize your database by copying or moving data (entities) among collectors, includes, or parts.

Procedure:In order the accomplish the above objective we need to follow following steps:

• Import the model into hypermesh.
• clean up the topology.
• Extract the mid surface.
• mesh the extracted mid surface using 2dmesh.

1. Import the model into hypermesh: We import the geometry model into the hypermesh using import geometry in menubar.

2. Clean up the topology:In order to extract the midsurface we make sure that the cad model that is imported is free from topology errors i.e any deformation occurs while importing the file into hypermesh or any in the cad file itself.

note:in this model we don\'t have any such type of errors so we can proceed to further steps.

3.Extract the mid surface:

• In order to extract the mid surface we first make sure that the model is free from errors.
• Then we extract the mid surface using auto mid surface option in geometry pannel.
• We extract the midsurface for the hood individually for each components and assign the properties.
• The individual components are inner pannel,outer pannel,latch and hinge.

4.meshing:

• Inorder to mesh the component we ensure that the extracted mid surface is cleafrom topological errors..
• We mesh components individually using automesh in 2d mesh pannel.
• we mesh the components by assigning the element size as 5mm and element shape as quads.
• we first mesh half of the components and then we mirror it to other half using reflect option.
• we make the mesh more finer and eleminate trias as much as possible.
• While meshing of the mesh didnt properly attach to the components then we increase or decrease the node count for proper capturing of surfaces.
• After completing the mesh we check for the quality criteria and reorganise the elements where they fail to the given quality criteria.
• Then we mirror the mesh to other half of the component.
• After reflecting the mesh we fill the gap between mesh using the edges option in the tools pannel.
• The given quality criteria is below:

S.N	Quality Criteria	Value
1	Aspect Ratio	5
2	Skewness	45
3	Warping	15
4	Taper	0.5
5	Min. Length	2mm
6	Max. Length	8mm
7	Min angle Quad	45
8	Max angle Quad	135
9	Min angle Tria	20
10	Max angle Tria	120
10	Tria %	10

Conclusion: We have extracted the midsurface of the component and meshed the model according to the given quality criteria.