Meshing of Vehicle Side Door Plastic Model | HyperMesh

AIM : To mesh the plastic component of a passenger vehicle side door as shown below with the given quality criteria.

Quality Criteria –

Target Element Length = 4 mm

PROCEDURE :

At first we will open Hypermesh and choose our User Profile as RADIOSS. Then we will import the model using Import Tab. After importing the model in Hypermesh, we can see a component in the component tree named lvl0. As it is quite complex model we will divide the model into six parts and store them in individual components to make midsurfacing and meshing easy. As our model is normal to XZ axis, we will split our model twice in X-axis and once in Z-axis. To do this we will go to Surface Edit panel in Geom page. We have to trim our model with an axis or a plane so we will go to trim with surfs/plane subpanel where we will select the required surfaces to be trimmed with respect to required plane and a base point. Then we will click on trim and thus we can divide the model in six parts as follows,

Now we will move these six parts in six different components named as 1, 2, 3, 4, 5 and 6 respectively. To move the respective surfaces we will make the assigned component as our current component and then we will go to Organize panel in Tool page and we will select the required surfaces to be moved, we will duplicate them to current component and then we will click on Move. Now the model is easier to perform midsurfacing and meshing.

First we will start with the Geometry cleanup and midsurfacing of component 1 which is shown below,

We will hide all other components. Here we are going to manually midsurface the component. Before performing midsurfacing we will make sure that the topology and geometry of the model is perfect for midsurfacing. If there are any surface defects, we will remove those defects using suitable commands from Quick edit panel. Now we can proceed with the midsurfacing. In the model, there are two different surfaces, the outer surface and the inner surface. The outer surface will be consider as the base surface for midsurfacing and the inner surface has similar profile as the outer surface along with different ribs and attachments.

We will create new component named 1_Midsurface where we will store the midsurface. Then we will measure the distance between inner and outer surface by pressing F4 and navigating to distance panel. We will go to Offset subpanel under Surface edit and select the outer surface which we will offset inwards for specified center distance. After generating the base midsurface, we will take the midsurface of ribs and attachments. Before this we will remove the surface fillets which are less than 2 mm. This can be done in surf fillets option in defeature panel where we will find fillets in selected surfaces and remove them to obtain better geometry for midsurfacing. Now again we will navigate to Offset subpanel under Surface edit and select the ribs and attachments which we will offset for specified center distance.

As the ribs and attachments are not connected to the base surface, we will connect them using surface edit panel. Here we will extend the ribs and attachments to the base surface using extend over edges command by selecting lines to extend over and surfs to target. In some instances or for improper geometry, we will use Translate command in Tool page to translate the surfaces and then extend them to base surface.

Now to mesh the surfaces, we will have to perform the geometry cleanup on the component to clean up the model geometry which may contain free edges, merged edges or surfaces, missing surfaces or missing surface continuity, etc. In Geometry Cleanup, we will use toggle edge option, split surf-node option and replace point, add/remove point, add point on line options, etc. to obtain the better topology for meshing. The result of midsurfacing is as follows,

Now we will proceed for meshing. We will mesh the component with given quality criteria in Automesh panel in 2D page or by pressing F12 shortcut key. To reduce the number of Trias generated in the mesh, we will keep remeshing the elements. This method is generally carried away when there are a lot of Trias or opposite facing Trias as we want the model to have more Quad and less Tria elements as the orientation is better in Quads. Now we will check the quality index of the meshed elements under Quality Index panel in 2D. If any elements fail in worst quality, we will optimize the elements using Cleanup Tools. Then we will check for the specified quality criteria. The elements failing the given quality will be optimized in similar way using Cleanup Tools. To obtain better mesh flow and connectivity, we will use Align, Project and Replace commands as well.

In the similar way we will take the midsurface and mesh the other five components.

Midsurface Result :

Now we need to combine and connect all the meshed elements to complete the meshed model. So we will move and gather all the meshed elements in a single component named as lvl0_Mesh using Organize panel. After moving elements from different components, we will have to connect the elements to obtain connectivity throughout the mesh. We can obtain this by using equivalence command in edges panel under Tool page. In most of the cases, we will use the replace node command to connect the elements. So after connecting all the elements, we will remesh some areas where we can improve the mesh quality by using 2D Automesh panel. Then we will again check for elements failing in quality criteria and we will optimize the failing elements to obtain the final improved mesh of our model as shown below,

At the end we will have to specify the thickness to the elements as per the parent model geometry. So we will measure all the different surfaces, ribs and attachments to obtain the value of the thickness which we need to apply by using distance command. As a result we will get that the different thickness values in the model are approx. 1mm, 2mm, 2.8mm, 3.5mm, 4mm, 5mm, 6mm, 10mm, 27mm etc. So we will create 9 new properties in the Model browser and we will assign these thickness values for each property. Along with this we will also create 9 new components for each thickness value named as ElementThick_2mm, ElementThick_2.8mm and so on. Now we will select and move the elements to these components according to the thickness of their position in parent geometry by using Organize panel. To achieve better distinguishability of elements for different thicknesses, we will assign different colours to the elements. To check whether the elements have proper thickness assigned to them, we will view the elements in 2D Detailed Element Representation format. Thus our model is ready.

Model Tree :

Meshing Result :

CONCLUSION : The passenger vehicle side door model is meshed based on the given quality criteria. There are no discontinuties or free edges between the elements and almost every element is passing the given quality criteria.