Week 6-Meshing of Hood Challenge

PREPROCESSING OF HOOD USING HYPERMESH

MESHING OF HOOD:-

INTRODUCTION:-

The hood (North American English) or bonnet (Commonwealth English) is the hinged cover over the engine of motor vehicles. Hoods can open to allow access to the engine compartment, or trunk (boot in Commonwealth English) on rear-engine and some mid-engine vehicles) for maintenance and repair.

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 a pedestrian vehicle collision. The front portion of the vehicle gets damaged including bonnet when met with an accident. 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 (weighting) of certain of the functional requirements normally associated with closures such as air tightness, passenger safety, low 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. It is 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 requirements.

The followings are the design considerations involved in the design of Engine Hood.

• Pedestrian Safety
• Vehicle quality
• Occupant Safety
• Styling
• Manufacturability

Types of Hoods:

• Invalid Hood or Built IN
• Wrap Around Hood
• Hood With Fenders
• Hood with Border Diagonal Frames
• Hood with Brace Frames

OBJECTIVE:- To extract mid-surface and generate mesh on Hood using Hyper mesh.

GIVEN MODEL:-

STEP INVOLVED:-

• Import the model into Hypermesh by using geometry option in the form of IGES format.
• Extracting Mid-surface by using offet skin method and assigning the properties.
• Meshing the surface with in the given quality criteria.

PROCEDURE:-

Step 1: Importing geometry and cleanup:

• To import the geometry, go to file ->> Import ->> select the file ->> Import.
• After importing the geometry, the geometry is checked for any missing surfaces or triple cons. If there are no errors present in the geometry then the geometry is ready for the mid-surface extraction.

Step 2: Extracting mid-surface and assigning properties:

• Mid-surface can be extracted by any of the 4 methods below.
  1. Offset + plane + sweep.
  2. Offset + plane.
  3. Offset
  4. Skin Offset.

• To extract the mid-surface, go to geom ->> mid-surface ->> select any extraction option ->> select the surface ->> extract. In this challenge offset + plane + sweep is used.
• After extracting the mid-surface, it is checked for any geometrical errors like needle faces, missing surfaces and triple cons. If any of the errors present then it should be rectified immediately.
• Now the properties like thickness, Material etc. need to be assigned to the mid-surface. To assign the properties, select model in database and right click and choose create and then property.
• Now all the properties are entered in the property tab and the properties are assigned to the respective mid-surfaces.
• To assign the properties to mid-surface, right click on the mid-surface and then select assign and select the respective properties which needs to be assigned.

• Since this component is axis symmetric, we can cut it in to half and mesh it. now we can mesh at last.

Step 3:- Generating mesh within the given quality criteria:

• Before generating mesh, the geometry is cut into smaller rectangles for good mesh flow.
• To generate mesh, go to 2D >> automesh >> select the surface >> mesh. To edit the mesh for proper flow, the elements are selected and meshed again.
• If any elements are failing for quality then cleanup tools option which is present in quality index can be used.

• 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.
• Thus we completed the Meshing process of hood.

FINAL IMAGE:-

CONCLUSION:-

• For the given Hood panel Mid-surface is extracted and mesh is generated with in the given Quality Criteria.
• For good meshing, we should always take care of necessary lines and edges by which we can create easy and structured mesh.
• Important thing in meshing is mesh flow, which should be followed by the given geometry.
• We should avoid as much tria elements as possible.
• 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.