Week 6-Meshing of Hood Challenge

https://drive.google.com/file/d/1nEaybdUpRsuLJ1jUVkOGKaeOJ9SuDD0c/view?usp=sharingIntroduction:

The movable cover above the engine of a car is referred to as the hood (North American English) or bonnet (Commonwealth English). On some rear-engine and some mid-engine vehicles, hoods can be opened to provide access to the engine compartment or trunk for maintenance and repairs.

In order to lessen the harm to pedestrians in the case of a pedestrian vehicle collision, work has recently been done on the bumper and hood design of the vehicle front end. When in an accident, the front part of the car, including the bonnet, is destroyed. Therefore, it is necessary to modify the existing bonnet design or use a different material. The motor vehicle's movable engine cover, known as the bonnet, provides access to the engine compartment for upkeep and repairs. As most bonnets do not open directly onto the passenger cell, certain functional requirements that are typically associated with closures—such as air tightness, passenger safety, low cycle fatigue strength, etc.—are given much less weight.These measures aim to lessen the number of pedestrian accidents involving vehicles that result in fatalities as well as the seriousness of the injuries they cause. Years of research into the frequency of impacts and severity of injuries have led to rating systems and better design. The bonnet system provides access to the engine compartment for maintenance of the drive belts, battery, fluid levels, and lamp units as well as the power train. Fundamentally, it is a reinforced skin panel that must meet a number of safety and quality requirements.

Meshing of Hood:

Here we will see the Meshing of different parts of Hood.

Hood consists four different components as below:

• Inner Extract
• Outer Extract
• Hinge Reinforcement Extract
• Latch Reinforcement Extract

Quality Criteria:

Quality Criteria for the Meshing of all the components are given as below:

Target Element Length = 5 Units

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

Inner Extract:

• There are four different components in the file when we import it.
• First of all make sure that only “Inner Extract” component is active all other mask it.
• Delete all solids from the component.
• Create Mid surface for only Inner Extract by selecting particular surfaces.
• Since this component is axis symmetric, we can cut it in to half and mesh it.
• As shown in above image, only the marked portion is not symmetric.
• So we can mesh that at the last.
• As shown in above image, split the midsurface and keep half of that for meshing.
• Start the Meshing with the closed area with less free edges.
• And avoid washer surfaces if possible.
• Keep the Mesh flow as per geometry and create mesh with less tria elements.
• Complete the mesh of the hald portion of the Inner Extract as shown in above image.
• Now we can reflect the elements on the other side and complete the total mesh on the component.
• As shown in above image, elements are reflected on the other side.
• Make sure that elements are in proper connectivity.
• So, create equivalence between the elements which are in symmetric line and make them connected as shown in above image.
• Thus we can complete the Meshing process for “Inner Extract” component.

Outer Extract:

• Here we can see the component is axis symmetric, so we can cut it into half.
• As shown in above image, the component is divided in to half.
• Create Midsurface after deleting solids from Outer Extract as shown in below image:
• As shown in above image, the hemming portion of the component is very thin.
• So, after creating midsurface, we can toggle the extra edges and split the component from the curvature area as shown in above image and easily create mesh without minimum length element.
• For easy and structured mesh, create rectangular portions by splitting the geometry with lines as shown in above image.
• Start with the curved or radius portion to avoid minimum length elements and step by step create mesh as shown in above image.
• We can further divide the curved portion marked in above image and create better quality elements in that region.
• Reflect the Mesh and create equivalence in the symmetry region.
• Thus we can complete the Mesh of “Outer Extract” component with better mesh flow.

_ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Latch Reinforcement Extract:

• Delete solids and create Mid surface for Latch Reinforcement Extract component.
• Do necessary cleanup and toggle extra edges.
• Remove edge fillets from marked portion for better mesh quality.
• As shown in above image, create washer surface with 5 mm distance and split the surface for better mesh structure.
• Keep the mesh flow as per geometry.
• Avoid tria elements at the free edges.
• As shown in above image, create mesh at the centre first and then proceed further for good mesh and complete the entire mesh for Latch Reinforcement extract.

_ _ _ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Hinge Reinforcement Extract:

• Here there are two components in Hinge Reinforcement Extract.
• If we create mesh only for one, we can reflect it on other.
• So, delete solids and create midsurface for only one part.
• As shown in above image, avoid creating washer surface for the holes for better mesh arrangement.
• Toggle the edges where minimum length element can occur.
• As shown in above image, mesh is created at the inner most area where less free edges are there.
• Then followed by them, rest of the part is meshed.
• As shown in above image, after creation of mesh on one part, with reflect option, mesh is reflected on the other part as well.
• Thus we can apply mesh on both the parts of Hinge Reinforcement Extract.

_ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Thickness:

• After meshing all the components, apply 2 units thickness to all.
• After applying thickness, complete Meshed Hood will look as shown in above image.

_____

________________________________________________________________________________________________________________

Mesh Results::

____________________________________________________________________________________________________________________

Inference:

• First thing to do with any given model is geometry cleanup and removing or toggling extra edges or lines.
• For good meshing, we should always take care of necessary lines and edges by which we can create easy and structured mesh.
• If there is small gap between two fillets, we can toggle one of the edges and simplified the meshing area to avoid minimum or maximum length elements.
• Important thing in meshing is mesh flow, which should be followed by the given geometry.
• We should avoid as much tria elements as possible.
• There should not be any rotational quads, which can disorient the analysis process and we can get poor results.
• We cannot avoid tria elements at the rounded or curved portions, so the elements at that area should be taken care with different splitting the surface.
• Where the elements are of poor quality, we can mask them any separately work on them to be corrected.
• Make sure that tria elements do not break the flow of the mesh.
• Thus, we can create good mesh with good arrangements of tria and quad elements and with proper flow and remeshing techniques.