Hood design-Week 2

HOOD

• The car’s hood consists of an inner and an outer panel. The inner panel provides strength, while the outer panel is just a metal cover. The underside of the hood is often covered with a sound-absorbing material.
• Hood are typically made out of steel or aluminum, although aftermarket manufacturers may manufacture hoods out of fiberglass, carbon fiber, or dry carbon.
• The hood or bonnet is the hinged cover over the engine of motor vehicles that allows access to the engine compartment for maintenance and repair. On passenger cars, a hood may be held down by a concealed latch.
• Some high performance cars have ‘hood scoops’ which channel outside air directly to the air filter, which gives improved performance and efficiency.
• It is hinged thin sheet which covers and protects the main parts of car like engine. Its main function is to direct access to the engine, bettry and other crucial parts of the cars for repair and maintenance and to protect these parts from direct sunlight and dust. It also gives good looks and help to design car aerodynamically stable.
• Regulations have come into effect in recent years that place a limit on the severity of pedestrian head injury when struck by a motor vehicle. This is leading to more advanced hood designs.
• The hood release is a small lever, which is usually mounted under the dash. It is connected to the hood latch by a cable. The hood latch has a safety feature, which requires a second latch to be released before the hood will open. This is to prevent accidental opening while driving.

DATA:

Hood Inner Panel has been designed by following the master data:-

Data used:

Hood Thickness Information

• Outer Panel Thickness = 0.75mm
• Inner Panel Thickness = 0.75mm
• Reinforcement Thickness = 1.5mm

DESIGN:-

Inner panel:
The inner panel supports the outer panel. it consists of embosses & holes. Embosses provide stiffness as well as it dissipates energy towards reinforcement.

HOOD INNER PANEL SECTION INERTIA ANALYSIS

the calculation for section modulus,

We consider the MOI (Min) to understand what is the

MOI (Max) = 2.500049219e x 10⁶ mm⁴

MOI (Min) = 8.750351563e x 10⁵ mm⁴

Y = 942/2 = 471 mm

S_Max = 2.500049219e x 10⁶ / 471 = 14428.5316 mm³

S_Min = 8.750351563e x 10⁵ / 471 = 1442.85316 mm³

^{HOOD INNER PANEL DRAFT ANALYSIS}

^{The draft analysis technique is used to analyze whether our part model created in CAD is manufacturable based on the draft condition applied. Here the part should get easily removed from the dies panel.}

^{Outer panel:-
Outer panel is a outside cover for engine and its a used to make a car looks good.}

^{Corner Relief:-
There are many types of Hemming process but in Hoods Roller hemming is used. In this process the roller will be rolling over the edges of the Outer panel to close it with the inner panel. These rollers will be rolling over 2-3 time for perfect closing. so, the certain force is being used by rollers to all the corners but there are some areas where the roller cannot tighten the part properly so thats why we give some relief to the corners.}

Hemming:-

• The outer panel & Inner panel can't join by any welding process if we did it will leave a spot on the outer panel and it will spoil the look of a car. so, to join inner and outer closure panels together we use the Hemming process.
• It is the process of bending/folding the flange of the outer panel over the inner one.
• The flange of the outer panel is bent over the inner panel in progressive steps by means of the roller hemming head.

ASSEMBLY OF HOOD INEER PANEL, OUTER PANEL, STRIKER AND HINGE

Reinforcements:-
Reinforcements are used to provide more strength to the assembly.

1. Latch & striker
2. Hinge

LATCH & STRIKER:-
Latch & striker is used for locking the hood with the car.

HINGE:-
Hinges are used to connect the hood & cowl panel of an automobile. it enable the opening & closing operation of the hood.

Position of Hinge & Striker:-

The hinges should be usually placed on both sides of the hood in such a way that the strike fits exactly into the hole provided.

To ensure these conditions:-

1. Both the hinges should be on the same axis.
2. The centre of the striker's circular trajectory should be always perpendicular to the hinge axis.

CONCLUSION:-

Thus as per the given parameters and as per the EuroNCAP safety standard the Car Hood Design is completed and draft analysis is taken to find the part is drawnable in manufacturing using NX CAD.