Hood design-Week 2

HOOD DESIG

DEFINITIONS OF HOOD:

The hood or bonnet is the hinged cover over the engine of motor vehicles. Hoods can open to allow access to the engine compartment (or trunk on rear-engine and some mid-engine vehicles) for maintenance and repair. In hood region there are consist of four parts which we tell as hood region.

1. Hood outer panel
2. Hood inner panel
3. Latch and Striker re-enforcement
4. Hinge re-enforcement

HOOD OUTER PANEL:

• Hood outer panel is the upper or outer view of hood which good in asthectic view and safety fro accidents. it gives important to pedestrian safety.then mastic is used to seal the outer and inner panel.

HOOD INNER PANEL:

• Hood outer panel is the part that gives strength and rigidity to the outer panel. The master section represents the initial emboss shape and size. Then we provide the emboss for the latch and hinge elements after fixing the location.

RE-ENFORCEMENT:

• Reinforcements are provided according to the design requirements. Mainly it is provided at the hinge and latch regions to improve the strength locally. Usually, the thickness of reinforcements will be higher than that of the inner panels and the value varies according to cost and requirement. According to the design requirement here, it is given 1.5mm thickness to both hinge and latch reinforcements.

Latch Trajectory:

Latch trajectory is given by the circle drawn from the hinge axis point. The hinge axis point is the center point of the hinge axis. First, we can fix either the latch or the hinge. If we have fixed the hinge position then we should plot the Trajectory circle for the latch. For proper mating conditions, the striker axis through the tip of the striker should be tangential to the latch trajectory.

Mastic Data:

Mastic points are those points of the hood inner panel which are in contact with the hood outer panel with the help of sealants so as to minimize the effect of the vibrations produced by the engine.

Following are the design considerations for the mastic points

• The diameter of the mastic points was taken as 5mm.
• The distance between the mastic point and the hood outer panel is 5mm.

The distance between two mastic points was kept in such a way so as to minimize the vibrational effects

Emboss definitions

Throughout the inner panel, we provide different embosses. We can increase the stiffness of the inner panel through these embosses. The shape and size of the emboss also determine the direction of the force distribution resulting from a frontal collision. The force should be always distributed away from the passengers. Here in the figure the embosses are designed in such a way that the force is directed to either side of the car.

Embosses:

Various embosses were made in the hood inner panel by keeping in mind the following design considerations

• Pedestrian safety during the frontal crash.
• To improve the strength and stiffness of the body.
• the embosses were designed in such a way that the distance between the hood inner panel and the outer panel was kept 5 mm from the points it had to be attached to each other.
• Hinge emboss was done keeping in mind the striker and hinge axis correlation.

Deep Drawing:

Deep drawing is one of the most widely used processes in sheet metal forming. Apart from its use in many other sectors, it is applied in the automotive industry for the manufacturing of car body parts. The deep drawing process is a forming process that occurs under a combination of tensile and compressive conditions.

Sheet metal blank is radially drawn into a forming die by the mechanical action of a punch. It is thus a shape transformation process with material retention. The process is considered "deep" drawing when the depth of the drawn part exceeds its diameter. This is achieved by redrawing the part through a series of dies. The flange region (sheet metal in the die shoulder area) experiences a radial drawing stress and tangential compressive stress due to the material retention property. These compressive stresses (hoop stresses) result in flange wrinkles. Wrinkles can be prevented by using a blank holder, the function of which is to facilitate controlled material flow into the die radius.

Hemming:

Hemming is the process of joining the hood inner panel and the hood outer panel. Due to the styling finish of the vehicle both the panels cannot be joined using the welded joints so in order to avoid these joints hemming is used. Hemming for the hood was done with the help of the hemming data.

HOOD ASSEMBLY:

HOOD OUTER PANEL

HOOD INNER PANEL

RELIF

HEMMING