Meshing and geometry cleanup of hood components of vehicle using hypermesh

Objective: To mesh the hood components and to maintain the quality criteria as shown below:

Procedure:

1) First open the file of the hood having extension as .stp in hypermesh with optistruct profile.

2) After opening the file all the solids are deleted and midsurface is extracted seperately for every component. Midsurface is extracted by using

Geometry-Midsurface-auto midsurface-extract options-skin offset-surfaces

Note: skin offset is selected because while using other options there was error in automidsurfacing.

after that thickness values are assign to midsurface.

3) Hide the original component so that only midsurface is visible Now observe the geometry and plan your cleanup strategy to obtain meshable surface.

4) After extracting the midsurface geometry cleanup is performed using toggle option in edge edit for supressing the unwanted surface edges for getting better surface also autocleanup is performed.

5) Now generate 2D mesh by using automesh with mesh type as quads and elemnt size of 5mm.

6) Now from tools option go to check elements and enter the values of quality criteria.

7) Now check for the each criteria in check elems options. for e.g click on warpage> 15.

8) For displaying all the failed elements,

cick on savefailed - Mask - elements -retrieve - click mask - reverse

It will display all the failed elements and we can work on those elements to maintain the given criteria.

9) Element cleanup tool :

In qualityindex after entering required quality criteria, element cleanup tools are used for minimising mesh quality errors.

i)element/node optimize : First select the node or element optimize option and click near the elements which are worse,fail, etc. it will optimize the worse nodes and fail elements.and the mesh quality errors gets eliminated.

ii)Drag tria elements: used to drag the tria elements.

iii)split quad elements: used for splitting the quad element.

iv)combine tria elements: used to combine two tria elements.and to form quad element from two tria elements.

v)smoothing: Select the elements for smoothing for better curvature.

Note: Jacobians are always present on rotational quads ans we have to remove them.

10) Remove all the errors one by one which are mentioned in the check elements.

As we can see in the bottom left corner 0% failed elements is showing.

11) Obtain mesh with no quality errors and also with the better mesh flow or mesh without any rotaional quads, and percentage of tria elements within the given criteria.

Fig: Latch component

12) Tools used to generate final mesh with given quality criteria and better meshflow:

Rename- It is used to rename the components,curves,blocks,assemblies etc.

find attached - All the elements will be visible which are attached to selected node.

Reflect - This command is used for mirror the elements, this is used for mirror the elements of outer body.

Duplicate - This is used while reflecting to keep the original elements,surfaces etc.

Project - To project elements on to the surfaces etc.

Replace nodes - By using F3 button as shortcut key this is used for minimising the gaps between the two elements or to eliminate any free edges present between two element.

Find edges - To display any free edges between the elements.

Result and conclusion:

1)Midsurface is created.

2)And thus by using some tools and element cleanup tool, final mesh with elemnt type as quads and element size of 5mm is created and the given quality criteria is checked and satisfied. Here are some images of final meshed geometry.

Outer body

Hinge

Inner body