Hood design-Week 2

HOOD DESIGN-

Introduction:-

Hood is main component of a car at the front portion. It is used to decorate the car & add luxurious look.

Hood design consideration:-

The hood of a car is considered as the frontal BIW enclosure component. Bonnets are designed to reduce air resistance as the air flows around the car. Apart from this, bonnets are also designed to meet several other requirements. They serve a great deal of purpose in protecting the passengers inside the car & the pedestrians in the event of an accident. It also acts as the cover for the engine.

The European New Car Assessment Programme (Euro NCAP) is a program for evaluating the safety of new cars in Europe. It has developed test specifications and rating systems for evaluating pedestrian injuries caused by impacts with the front of vehicles. These tests include a series of impacts designed to bio-mimitate a 40 km/h collision.
They describe a scenario in which a car first hits one of a pedestrian's legs while the pedestrian is positioned laterally.Since head trauma accounts for the majority of fatalities, tests are performed on the leg, upper leg, and most importantly the head.
Therefore, the high impact area for adults and children has less thickness to prevent severe head injuries.In addition, there should be no reinforcement in that area because, in the event of a head collision, the hood will absorb the impact energy, causing the hood to collapse and protecting the head from serious injury.
The protection of the car's occupants in the event of a frontal collision is another important design consideration.The shape of the hood should be such that, in the event of a collision, the force should travel upward through the embosses and toward the car's body.thereby safeguarding the occupants within.
The following components are used in the hood assembly for this report: Hoodouter panel, Hoodinner panel, Hinge assembly, Striker assembly, Hood thickness: Outer panel thickness: 0.75 mm, Inner panel thickness: 0.75 mm, Reinforcement thickness: 1.5 mm, Inner Panel: We can only study and implement pedestrian and driver safety in the inner panel.Only this panel can be used to attach reinforcement, embossed pieces, mastic points, and other items.
The present invention aims to provide a hood inner panel with the ability to reduce the reaction force of the hood inner panel despite an increase in vehicle hood deformation and a sufficient capacity for energy absorption.

Outer Panel-

We can also call it as cover of inner panel. It is the part, which gives luxurious look to the hood or bonnet. Outer & inner panel can not join by any welding process like spot welding or rivet, which spoil the outer look of a car. The outer panel is generally extracted model from the prototype design.

Hinge Assembly-

Hinge is a component that fixes the hood to the fenders of the car. The latch must be fixed perpendicular to the hinge axis so that the hood opens or closes properly.

Striker Assembly-

Latch & striker is used for locking the hood with the car. It is usually placed on the space provided on the inner panel.

The process involved in designing hood as a sheet metal operations is Blanking

Hemming

Punch cutting or piercing Deep drawing Embossing

Hemming-

Hemming is a sheet metal forming process in which sheets are joined by bending it usually to 180 degree. Automotive body panels & parts such as deck-lids, trunk-lids, doors, hoods & tailgates are formed by hemming processes.

Roll hemming is carried out incrementally with a hemming roller. An industrial robot guides the hemming roller & forms the flange. Roll hemming operation can also be divided into several pre-hemming & final hemming process steps.

Coventional die hemming is suitable for mass production. In die hemming, the flange is folded over the entire length with a hemming tool. Normally the actual hemming is a result of a forming operation in which the flange is formed with a hemming tool after the drawing & trimming operations have been completed.

While doing the hemming process a relief angle is formed as a product of hemming when attaining at the corner of the sheet.

Deep Drawing-

Deep drawing is a manufacturing process that is used extensively in the forming of sheet metal into a cup or box-like structures. Pots & pans for cooking, containers, sinks, automobile parts, such as panel & gas tanks, are among a few of the items manufactured by sheet metal deep drawing.

A deep drawing of sheet metal is performed with a punch and die. The punch is the desired shape of the base of the part, once drawn. The die cavity matches the punch and is a little wider to allow for its passage, as well as clearance. For many calculations, the sheet metal thickness is assumed to remain constant. There are changes in thickness in certain areas, due to force involved.

Embossing-

The sheet metal embossing operation is commonly accomplished with a combination of heat & pressure on the sheet metal, depending on what type of embossing is required.

A sheet metal is drawn through the male & female roller dies, producing a pattern or design on the sheet metal. Depending on

the roller dies used, different patterns can be produced on the sheet metal.

Latch trajectory-

While opening or closing the hood, the latch must be perfectly aligned to the fixing or striker point. For that, the latches trajectory must be perpendicular to the hinge axis.

Hood Assembly- Output

TREE STRUCTURE

Conclusion-

We have designed a hood that falls under the rules & regulations of the manufacturer's standards.