All Courses
All Courses
Courses by Software
Courses by Semester
Courses by Domain
Tool-focused Courses
Machine learning
POPULAR COURSES
Success Stories
HOOD DESIGN Aim: - To Design and assemble the Car Hood/Car…
Prem Kumar
updated on 07 Apr 2021
HOOD DESIGN
Aim: - To Design and assemble the Car Hood/Car Bonnet Inner panel
Here we are going to understand What Is the Hood/Bonnet? What are the Materials Used to
Manufacture the Hood? What are the design considerations?
About Hood/Bonnet:
The hood or bonnet is the hinged cover over the engine of motor vehicles that allows access
to the engine compartment, or trunk for maintenance and repair.
On front-mounted engine cars, the hood may be hinged at either the front or the rear edge, or
in earlier models, it may be split into two sections, one on each side, each hinged along the
centreline. A further variant combines the bonnet and wheel arches into one section and
allows the entire front bodywork to tilt forwards around a pivot near the front of the vehicle.
Materials Used:
Hoods are typically made of the same material as the rest of the bodywork. This may include
steel. aluminum fiberglass, or carbon fiber. However, some aftermarket companies produce
replacements for steel hoods in fiberglass or carbon fibre to make the vehicle lighter.
Before we dive into the design, let us understand the rules and regulation standards for
designing the hood.
● A perfect hood design means it should have a great impact distribution angled outside
the car.
● In Japan and Europe, regulations have come into effect that places a limit on the
severity of pedestrian head injury when struck by a motor vehicle. This is leading to
more advanced hood designs, as evidenced by multicore hood inner panel designs.
● European Enhanced Vehicle-Safety Committee (EEVC), European New Car
Assessment Program (euro NCAP)
Design consideration:
While designing the hood we should have to focus on the Pedestrians safety, Occupant
Safety, opening angle, vehicle quality, etc.
Pedestrians safety:
Pedestrian safety is one of the important criteria which must be taken into consideration
during designing a hood. Based on the wrap-around distance and pedestrian head impact
zone, the hood is designed so that during a collision impact on the person must be reduced.
Around the impact zone, the hood is made softer by removing material. There are two main
zones in the hood that are considered while designing it. The Child head impact zone
(1000mm to 1500mm) and the Adult head impact zone (1500mm to 2100mm) as shown
above. The wrap-around distance is the distance from the ground level to the end of the hood.
The side reference line and the wrap-around distance are related to each other. If the side
reference line is on the fender, the wrap-around distance will be more and the impact zone
will be less and vice versa.
Opening angle:
The head clearance zone is the clearance such that when the hood is in fully open condition it does not
hurt the head of the person that is standing next to the hood. This is controlled by the opening angle of
the hood. The opening angle of the hood is decided for the region the car is manufactured. Some
regions may have people with an average height of 5.5 ft and another region may have people with an
average height of 6 ft. so deciding the right opening angle for the hood is an important criterion.
A hood stay is a device that is used to keep the hood in an open position. there are two types
of hood stays 1) Support Rod 2) Gas Stay
Support Rod
The support rod is usually inside the engine compartment, when we open the hood and keep it in open condition, one end of the support rod attaches to the hood and supports it. this support rod has to be fixed manually onto the hood. The design of the support rod is not linear but it should have some bends to increase the rigidity and strength of the rod. the support rod should be mounted such that it does not collide with other parts, also the support rod should be mounted on the opposite side of the battery to avoid interference with each other.
Gas Stay
A gas stay is used to open the hood, keep it in an open state, and then closing the hood. This is an automatic process, that is the gas stay uses an
actuator to open and close the hood. one side of the gas stay is mounted on the body side and the other side is mounted on the hood. gas stays for the front hood are mainly used in high-end performance cars.
Components of the hood/Bonnet:
Outer panel:
The outer panel is actually called the skin of the vehicle which is designed by the styling team to get a good look for a vehicle by covering the inner panel and engine parts of the car. This part should not be welded to the inner panel but using the sealant and mastic points makes contact between the inner and outer panel which acts as a bond between both and makes the hood stiff.
Inner panel:
The main part of the hood gives support to the outer panel of the car and with its embossing shapes dissipates the force in different directions when the vehicle takes crashes to not injure the men in the car.
Latch:
It is a part that helps in locking the hood with the striker which is mounted on the engine block when
it is not in use. It plays a major role in opening and closing hood for maintenance of car engine and
gives a tight locking position not to create undisturbed noises when the vehicle is running.
Hinges:
The hinge consists of two parts- hinge at the inner panel and hinge at the engine compartment. This
coupling allows the hood to open and close, as well as makes contact between the engine block to the
hood. It also controls the lifting of the bonnet mitigates the consequences of a collision between a
pedestrian and a vehicle.
Given Inputs
● Hood Styling Surface
● Hood Thickness Information
● Master sketch
● Hemming Data
● Relief rear section
● Front relief
Hood Thickness Information
● Outer Panel Thickness = 0.75mm
● Inner Panel Thickness = 0.75mm
● Reinforcement Thickness = 1.5mm
DESIGN INNER PANEL:
MASTER SECTION
The Master section is already provided by the team and the manufacturing requirements
The figure shows the path of forces on the hood in case of direct accidents
Here emboss are created in such a way that the forces are disturbed in order to avoid the direct impact to the passenger sitting inside the car
DESIGN OF HOOD OUTER PANEL WITH HIM:
Bottom view of outer panel
HEMMING DESIGN PARAMETERS
SECTION VIEW OF OUTER PANEL
humming data parameters
relief rear section
Latch Reinforcement
H- Hinge
HA- Hinge axis
CPS- Circle passing through striker, makes perpendicular to the striker endpoint.
The circle here is the trajectory of the opening of the hood and closing action, it's necessary that the trajectory line must pass through the end of the striker in order to work properly for the opening and closing action of the hood.
MASTIC DATA:
Mastic is the sealant applied between the hood's outer panel and the hood's inner panel
the blue circle components are mastic sealants
Mastic sealants have an 80mm diameter range of effect which holds and joins the outer panel and inner panel having a 5mm thickness
EMBOSS:
Embossing is a metal forming process for producing raised or sunken design or relief in sheet materials by means of matched male and female roller dies, theoretically with no change in metal thickness, or bypassing sheet or a strip of metal between tools of the desired pattern.
Characteristic of the metal embossing process include:
Materials commonly used in the metal embossing process include:
Leave a comment
Thanks for choosing to leave a comment. Please keep in mind that all the comments are moderated as per our comment policy, and your email will not be published for privacy reasons. Please leave a personal & meaningful conversation.
Other comments...
Week 12:- Documentation Challenge
Bill of Materials (BOM):A bill of materials (also known as a BOM or bill of material) is a comprehensive list of parts, items, assemblies and other materials required to create a product, as well as instructions required for gathering and using the required materials. The bill of materials can be understood as the recipe…
10 Nov 2021 05:49 AM IST
Week 10:- 2D Detailing Challenge
09 Nov 2021 11:25 AM IST
Week 9:- 2D Detailing Challenge
1.What are the drawing templates? A) Drawing Templates: If compared with the verbal or written description, drawing offers a far better idea about the shape, size & appearance of any object or simulation or location, that too in quite less time. Hence it has become the best media of communication not only in engineering…
01 Nov 2021 10:18 AM IST
Related Courses
Skill-Lync offers industry relevant advanced engineering courses for engineering students by partnering with industry experts.
© 2025 Skill-Lync Inc. All Rights Reserved.