Week 3 - 2D meshing for sheet metal

Aim :

For the given Hood model, Take the mid surface for all the components after checking the geometrical errors and mesh the mid surface with the given element Quality criteria.

Introduction :

The Hood or Bonnet is the hinged cover over the engine of motor vehicles. Hood can open to allow access to the engine compartment . In recent years , the work has been done on the bumper and hood design of the vehicle front end to reduce the injuries to the pedestrians in the event of pedestrian vehicle collision.The front portion of the vehicle get damaged including bonned when met with an accidient. so there is need to change the existing design of bonnet or by changing the material. The bonnet is the hinged cover over the engine of motor vehicles that allows access to the engine compartment for maintenance and repair.Bonnet usually do not directly open onto the passenger cell which greatly reduces the importance of certain of the functional cycle fatigue strength etc.The objective of these measures is to reduce the number of road accident fatalities and the severity of injuries sustained by pedestrians involved in a collision with a vehicle in urban traffic. Impact frequency and seriousness of injury has been studied for many years,resulting in rating systems and improved design.The bonnet system is an access panel to the engine compartment to enable maintenance of power train,drive belts , battery , fluid levels and lamp units. its fundamentally a reinforced skin panel with many safety and quality requirements.

Engine Hood :

The hood which is also known as ENCON , serves as an access panel to engine compartment of an automobile . it is an assembly made of outer and inner panels to meet various safety and design requiements.

The following are the design considerations involved in the design of engine hood.

• Pedestrian Safety
• Vehicle quality
• Easy to manufacture
• Styling
• Occupant safety

Meshing of Hood :

Hood consists four different components as below:

• Inner extract
• Outer extract
• Hinge Reinforcement extract
• Latch Reinforcement extract

Procedure:

Latch Reinforcment extract :

• There are four different compoenets in the file when we import it
• First of all make sure that only "Latch Reinforcement extract" component is active.
• Set length as 1mm for better geomerty shape
• Then we create the Target element as 5mm and save
• Next we set Quality critiria as per given and applying the given model
• Do the necessary cleanup
• Next we start to create the Mid surface
• Keep the mesh flow as per geometry
• Avoid tria elements at free edges

• As shown in above image , create at the centre first and then proceed further for good mesh and complete good mesh and complete at the entire mesh for Latch reinforcement extract.

Hinge Reinforcement extract:

• Here there are two compoenents in Hinge reinforcement extract.
• If we create mesh only for one , we can reflect it on other
• Toggle the edges where minium 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
• After creation of mesh on one other part as well
• Thus we can apply mesh on both parts of Hinge reinforcement extract
• we need check quality cirtria after meshing

Outer Extract:

• Here we can see the component is axis symmetric so we can cut it into half.

• Create midsurface after doing the necessary geometry cleanup in outer extract.
• As shown below image , the hemming portion of the component is very thin

• For easy and structured mesh, create reactangular portions by splitting the geometry with lines

• As shown the above reflect the Mesh . if we created proper mesh flow.
• Thus we can complete the Mesh of "Outer Extract" component with mesh flow.

Inner Extract :

• Create Mid surface for only inner extract by selecting particular surface
• Since this component is axis symmetric , we can cut it in to half and mesh it.

• As shown in above image , only the mark 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
• Keep the mesh flow as per geometry and create mesh with less tria elements
• Complete the mesh of the half portion of the inner extract.
• Now we can reflect the elements on the other side and complete the total mesh on the component
• Make sure that elements are in proper connectivity
• Thus we can complete the meshing process for "Inner Extract" component.

Mesh Result :

• Latch Reinforcement Mesh result shown below

• Hinge Reinforcement Mesh result shown below

• Inner Reinforcement mesh result shown below

• Outer Reinforcement mesh result shown below

Note : There is no any off element after checking the Quality critiria ( shown by above images )

Thickness :

• After Meshing all the componenets , apply the 2 units thickness to all
• After applying thickness , complete the Meshed Hood will look shown in below image

Thanks & Regards,

Vignesh.G