Design of backdoor

BACKDOOR DESIGN
OBJECTIVE:
To develop the car backdoor by using given surface method by automotive sheet metal design.
BACKDOOR:
A backdoor is located at the rear end of the car which gives access for the boot space to store luggage.,spare whhel etc.These doors can be operated mannualy or
eclectric powered.In most of the luxuary car is electric powered.
Back Door also called as 'Hatch', or 'Tailgate', 'Trunk-lid', 'Boot-door' is basically the 5 door in a 4-door car. It's the rearmost part of the vehicle which gives access
to the trunk and has mounts for wiper motor, tail lamps, hinges for supporting its weight in opened position, gas stays which help with its opening and keeping it
open, radars and cameras etc.

A backdoor is usually made up of 1 inner panel and 2 or 3 outer panels joined together by hemming and spot welding wherever necessary.

The material used for backdoor varies as per the price range of the vehicle. Most of the low cost vehicles use steel as it is cheaper and use parts that are stamped
using moulds. These parts are usually of uniform thickness and reinforcements are added to improve local strength where needed. The premium vehicles use
aluminium parts which are usually die casted and hence can have variable thickness. This removes the need of reinforcements hence keeping the weight even
lower as aluminium parts are lighter in comparison. On the contrary aluminium is more expensive than steel hence its applications are limited in cheaper vehicle.
Currently due to the extensive use of plastics trims and plastic parts the cost of aluminium is affordable for the manufacturers in all price brackets. Use of
aluminium reduces the overall weight of the component and hence the vehicle improving its fuel efficiency.
REINFORCEMENTS:
As mentioned for local strengthening reinforcements are usually provided. Instead of making the whole panel off a thicker sheet, a thinner sheet with thicker local
reinforcements wherever needed is preferred. The reinforcements are usually 1-1.5mm thick whereas the panel itself is 0.55- 1 mm thick.

Backdoor parts thickness value used in this design:
1. Outter panel - 0.75 mm
2. Inner panel - 0.75 mm
3. Reinforcements - 1 mm
DESIGN CONSIDERATION FOR BACKDOOR INNER PANEL:
1. Rear Visibility.
2. Support structures like hinges and gas stays.
3. Mounts for wiper motor, tail lamps, and other wiring loops.
4. Fit and clearances.
5. Boot space
6.Rear crash regulations and requirements.
7.Sealing and its functions.
8.Joining techniques like hemming, spot welding etc.
TYPES OF DOOR OPENING:
Top mounted door
Side mounted door
Bottom Door
In these project, I designed Top mounted door,So here we discuss mainly about top mounted door only.
COMPONENTS OF BACKDOOR:
Inner panel
Outter panel upper
Outter panel lower
Hinge reinforcement LH
Hinge reinforcement RH
Gas stay reinforcement LH
Gas stay reinforcement RH
Wiper motor reinforcement
Latch reinforcement
Plastic trim.

INNER PANEL:
Car backdoor inner panel is made of either steel or alumminium.Most of the luxuary car's inner panel are made of aluminium because of is properties.But the cost
of aluminium is high.
STEEL ALUMINIUM
PARTS Parts are stamped Parts are casted
REINFORCEMENTS Necessary Can be neglected
THICKNESS Constant Can be Varied
COMPONENTS More Lessin number
WEIGHT More Lighter
COST less in cost as compared to Aluminium More as compared to Steel
Cost of aluminium is more as compared to steel .TO easiy understand , the cost of aluminium for inner panel is higher than the cost of all parts of backdoor
together.
Bechmark between companies who are using steel and aluminum inner pane