Back door inner panel Design

BACK DOOR INNER PANEL DESIGN

INTRODUCTION TO THE BACK DOOR:

The back door is part of the car that lets you access the boot space or the trunk.

Figure:5a

(Figure:5a shows the complete parts of the back door inner panel assembly)

Parts of the Back door inner panel assembly:

1-Outer panel

2-Inner panel

3-Hinge Mounting Bracket

4-Hinge inner reinforcement

5-Wiper motor support bracket

6-Stay inner reinforcement

7-Stay mounting bracket

8-Latch inner reinforcement

People often call it by names such as hatch, tailgate, etc. Here the hatch refers to the hatchback cars where the boot compartment is opened and closed by the door known as a hatch, which extends upwards with the help of hinges and a set of gas stays or brakes.

(Figure 5b shows the representation of a hatchback below)

Figure:5b

Tailgates are also referred to as back doors. This name was coined for its unique way of opening, where the door collapses downwards with the help of hinges and stays. Some tailgates have rolled down glass windows.

(Figure 5c shows the representation of a typical tailgate design below)

Figure:5c-1&2

INNER PANEL DESIGN:

Figure:5d

The inner panel is designed to support the styling surface on the outside, which mainly acts as reinforcement and gives rigidity to the outer panel during the rear collision of the car.

(Figure 5d shows the type of embossing done to give the structure rigidity)

MAIN CRITERIA CONSIDERED FOR THE DESIGNING OF THE INNER BACKDOOR PANNEL:

• HEMMING AND RELIEF

Heming is the process of joining two surfaces using a set of rollers to bend the parent over the subpart. The parent part is the outer panel, and the subpart is the inner panel.

(Figure 5e shows the hemming cross-section below)

Figure:5e

Relief is done to decrease the stress concentration along the corners and decrease the clumping of metal along the corners; this is done by trimming the corner by a minimum radius for the rollers to pass along smoothly.

(Figure 5f-1,2&3 shows the relief provided on the outer panel below)

Figure:5f-1,2&3

• STRESS FLOW DIRECTION

In the inner panel, to act as a sound reinforcement, it needs to disperse the stress outwards and not inwards; hence in this design, the embossing is designed to move the stress outwards away from the center.

(Figure 5g shows the stress flow direction below)

Figure:5g

• DRAFT ANALYSIS

Draft analysis shows that the metal can be drawn with the particular design without any tear in the metal of disfiguration. So the above design has been analyzed using the tool on NX CAD with 5 degrees as the allowance (All green is good to go).

(Figure 5h shows the draft analysis below)

Figure:5h

• REINFORCEMENTS

Here extra reinforcements are used to provide more support for critical positions such as the latch position, hinge position, and stays for the hinge position. These plates can have a thickness ranging from 1-1.5mm.

(Figure 5I shows the Reinforcement positions below)

Figure:5I

• RENDERED IMAGES OF THE DESIGNED BACKDOOR

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