Hood meshing according to given mesh quality criteria in HyperMesh

OBJECTIVE:

Mesh the given components according to the given mesh quality criteria. There are five different sub-components which have to be extracted through the mid surfacing and further meshed.

Given mesh quality criteria:

PROCEDURE:

• Import the Hood.stp file in HyperMesh. It will have five sub-components.
• Extract the mid surfaces for each of the sub-components separately. Check the extracted mid-surfaces for unwanted free edges or irregularities.
• This mid-surface is used for 2D meshing further.
• Check the components symmetry and take its advantage for meshing. Mesh the component for symmetric half and reflect the created mesh onto the other half afterwards. This saves time.
• Now check for circular regions or fine curvatures. Create washer splits for circular regions for better mesh adaptability.
• Be aware of suppressed edges while doing auto-clean up. These edges are useful while meshing.
• Start with the one part and assign surface for meshing, go to 2D>automesh. Make use of edges for proper grading/mesh intensity.
• Increase or decrease the node intensity at edges to have structured mesh as much as possible. Make use of mixed elements if there are curved or complicated shapes because triangular elements capture the complicated geometry easily than quadrilateral elements.
• Then, move to the adjacent part which has been meshed properly. Take advantage of previous meshed region and try to create a good mesh in new regions with similar node intensity.
• After creating the mesh for a single region, check the mesh quality through tools>check elem. Set the given mesh quality criteria and see the affected elements.
• Various options like smooth, split, element edit, replace, combine, place node, element optimize, drag tria element can be used which are present in 2D mesh utility of HyperMesh.
• The option 2D>qualityindex, provides good edit options for mesh editing and displays the thresholds for mesh quality. The worst affected elements are highlighted and can be improved by editing.
• After this go to tools>edges and create edges by find edges option. This will give the free edges generated after meshing. Free edges in between the elements signify the element disconnectivity. So, these elements should be connected together and this can be done by \'replace\' node option.
• Go on creating the mesh to every region similarly step by step. Check the mesh quality index for every meshed region and resolve the errors as discussed above.
• Once the mesh is created for half symmetric region, go-to tool>reflect option. Select all elements and duplicate it before reflecting. Then again select the elements and choose the mirroring axis with suitable base node and reflect the elements on the other half.
• The reflected half will have a connecting boundary. This boundary can be detected through a \'preview equivalence\' option. These boundaries should be rectified by tools>edges>equivalence option.
• Meshed components are shown in the figures below.

Fig 1.1: inner_extract_body meshed

Fig 1.2: inner_extract_body magnified

Fig 1.3: outer_extract_body meshed

Fig 1.4: outer_extract_body magnified

Fig 1.5: Hinge reinforcement meshed

Fig 1.6: Latch reinforcement meshed

RESULT/CONCLUSION:

• Given components are meshed according to the given mesh quality criteria.
• Complex shapes/curvatures should be properly resolved and these surface should be split with split surf-node or split surf-line option. Big surfaces should be divided into simple blocks to get good quality structured mesh.
• The mesh quality should be checked for every small part of the component which has been meshed. This reduces the complexity and saves time for quality check at the end.
• For structural analysis, it is always better to have triangular elements rather than rotating quadrilaterals in curved or complex regions. So, rotating quadrilaterals should be avoided.