Design of backdoor

To design backdoor of a car using the design surface provided.

Door

A door is a hinged part which is used for entry and exit of the vehicles. Back doors are one of the type doors of the vehicle which are located next to the passenger seat which provides access to the luggage compartment. In most of the cars, these back doors are operated with the help of gas stay which in turn reduces the effort required to lift open the door. Some luxury cars have powered backdoor which in turn is driven by an electric motor. This kind of system is also called a powered trunk lid system. Hatchback or station wagons are sold as 3 door or 5 door models. In this case, the rear hatch is classified as door this is because it enters the passenger compartment. The naming is mainly used in Europe countries. In case of safety, the back door designed should meet the safety requirement for the rear collision.

Types based on working mechanism.

Gas stays type:

Gas stay types backdoor/lift gate/tailgate is an ideal and most commonly used tailgate mechanism from lower segment car to luxury car segment. The ideal components of tailgate consist of a hinge, door, gas stay and some rubber beadings for sealing of door which is shown in the image below:

Powered lift system:

Power trunk lid system is another sophisticated way of trunk/lift gate opening mechanism which is to automatically open and close of the trunk/lift gate and release of the latch by the touch of a button. The following image shows the component as used in the powered trunk/back door lift system.

Powered trunk lift system consists of a power latch, anti-pinch switch, PTG ass’y, PTG main switch. When the switch is pressed in the compartment or outside the power latch releases the latch and the entire backdoor is opened. The anti-pinch switch is located in order to avoid accidental hand insertion during the operation of the door.

These are the most convenient type of back door in which the bottom split is used as a support or even as a table for the tour going people.

MANUFACTURING METHODS:

Recently, there have been two approaches to reducing automobile weight. One is by using material lighter than steel and the other is by redesigning the steel structure. Although the former seems very effective, it is very expensive so that it may only be used for an expensive automobile. Therefore, the automobile industry is trying to use steel, which is not costly and recyclable. Lightweight steel can be achieved by improving the performance of the structure or adopting new manufacturing techniques. One of the efforts is the ULSAB (ultra-light steel auto body) concept.

ULSAB suggests three main weight reduction techniques such as hydro-forming and the tailor welded blank (TWB).

Tailor welded blank:

A tailor-welded blank is a blank that is comprised of two separate pieces of sheet metal that have been welded together prior to stamping. Tailor welded blanks allow the welding of the different grades, different thickness or different corrosion coatings together in order to give the properties needed in different areas, without increasing the number of tools needed to form the part and eliminating the fit ability concerns. They also allow a high degree of flexibility in designing parts and large blanks can be formed from much smaller sheets. The use of tailor-welded blanks would reduce the weight of the car. Having the ability to selectively place different thickness of material would result in weight reductions. An example of this used in production is the door inner panel. The only strength requirement on a door inner is in the region where the hinges attach to the panel.

Objective: To model the BACK DOOR containing various reinforcements according to Engineering Standard using NX CAD.

Software: NX CAD.

Design requirements:

Outer upper and lower panel reference.

Components in Back Door:

• Inner panel
• Outer Upper Panel
• Outer Inner Panel
• Reinforcements

Design considerations:

• Rear visibility
• Latch & Striker reinforcement
• Hinge &Gas stay reinforcement

Theory:

Back door is also called as tailgate, which is most important for rear visibility criteria and it allows access to boot space, more the thinner the back door more the boot space we get.

For back door to prepare we need outer panel reference, we have to prepare inner panel.

Back door can be made by two materials Aluminum or Steel.

Aluminum back doors are good at strength and also as their density is less it can improve the performance of automobile. But the only disadvantage is the are costly.

Here are the some differences on both materials.

With aluminum entire inner panel can be deep drawn but we cannot do this with steel cause of its ductility. Here is the weight difference of the back door made with two materials.

There is a drastic change in weight in the aluminum of 4.7kg.

Nowadays many companies stared using aluminum for this.

This are some Benchmarks results of aluminum.

Assembly sequence of the aluminum back door.

Conclusion:
By applying solid and surface modelling methodologies and accord of Engineering
Standards, the design of Back door was completed using NX CAD.