Hood Design

Hood (Bonnet): -

• hood is opening body panel that covers engine in front engine vehicle.
• inner panel of hood provides strength and outer panel provide style surface to cover engine.
• embosses are provide on hood inner panel to dissipates energy of front impact to outside car body than inside.

1. Opening angle: -

One of design parameter for design of hood is opening angle. This opening angle is being control by supporting rod or gas stay. The length of supporting rod controls the opening angle of hood.

Supporting rod is placed on engine and after opening is attached to hood or vice versa.

We basically attached hood to engine compartment using primary latch. And secondary latch is provided below the driver seat to initialize opening of hood. clearance distance of 10to 15 is provided on primary latch.

1. Hood Stay: -

• It is basically mechanism which hold hood in open position.
• They are two type of hood stay.one is supporting rod and other is gas stay.

Supporting rod: -

• It is simple to design and cost effective.
• The length of rod decides the opening angle.
• They are not straight always. Sometimes intermediate bend is provided to strengthen to hold hood in open position.
• During its locking it might create scar on automobile body which results in corrosion prone area.
• They are hot in temperature since lies near to engine which result in difficulty in handling.
• Too much of curvature will result in weak design hence max curvature should be 35 mm.
• It will be placed in other side of battery compartment.

Gas Stay: -

• No man power is needed.
• Costly as compare to supporting rod.

Reinforcements: -

• Reinforce are the one who are added in to compensate the loss of material happened in specific area locally.
• If it is at latch and striker mechanism, we will call it as latch and striker reinforcement. If it is near hinge then we will call it as hinge reinforcement.

Stiffener pad: -

• It is provided between inner and outer panel.
• This is basically hard sponge material specifically provided to reduce the vibration happening during running of vehicle.

Mastic point/ sealant: -

• It is also small rubber parts.
• It is also kind of glue which connect inner panel& outer panel. Since we are not able to add spot weld.

Hood zone and NVH are the design criteria for design of hood.

Hood Design in CATIA V5:

Styling team gives us styling data of outer panel of hood.

Master sketch is provided with us. We have to extract surface and we are going to create operation on half section of hood. After completing all operation, we are going to mirror the half component.

Design Consideration: -

1. 2 mm and 4 mm offset is given in order to accommodate mastic sealant between inner and outer panel.
2. 25 mm max offset given based on pedestrian standard.
3. 40 mm distance is given to accommodate engine and side angle are provided near to 45 degree in order to deep draw the hood panel.
4. Emboss pattern is created in such way that impact energy will be directed outside hood body.

1. Reinforcement plate are provided at latch and striker position and hinge position to increase strength in localized area.
2. Relief are provided while hemming outer panel over inner panel to take care of spring back effects.

Hemming portion: -

Mounting for latch and striker and hinge reinforcement: -

Hinge and striker and latch reinforcement plate: -

1.5 mm in thickness