Hood design-Week 2

HOOD DESIGN

Aim: To Design Hood outer panel, inner panel and the necessary reinforcements by following the Master section with the design parameter

Introduction: Hood is the main component of a car at the front portion. It is used to decorate the car and add a luxurious look. The shape of the Hood is made aerodynamic in order to minimize the air effect. Hood is generally used to access the parts easily such as radiator, engine and many other parts. A car hood, also referred to as a bonnet in some other countries, is the hinged cover that rests over the engine of a front-engine vehicle. Its purpose is to provide access to the engine for repair and maintenance. A concealed latch is typically used to hold down the hood. On vehicles with an aftermarket hood and on race cars, hood pins may be used to hold down the car hood. Hoods sometimes also contain a hood scoop, wiper jets, power bulge, and/or hood ornament. Car hoods are typically constructed from steel and sometimes from aluminum. Aftermarket car hoods may be constructed from various other materials, including carbon fiber, fiberglass, or dry carbon. The hood design may vary from one make and model to another.

while access for repairs and maintenance Hood can fix by two methods

1. Support Rod

2. Gas Stay

In the fig 1.1 shown Support Rod and Gas Stay

1. Hood Head zone for lock striker: In the fig 2.1 shows Hood Head zone for lock striker

Fig.2.1: Hood Head zone for lock striker

From the Fig. The opening angle of hood will give A, C, B And D with respect to the ground. those A, B, C & D are decided in the head zone. Opening angle varies from region to region depending on average human weight. Depending on the standards we are deciding the angle. So from the angle data, Support rod or Gas stay is designed. The position of Support rod is on the other side of the battery which is shown in the fig. below.

2. Adding latches and stiffener pad: Latches are added where and all the weight is added. On the inner panel we have Hinges and striker, which are attached to the inner panel so due to this attachment the strength of the inner panel is going weak. In order to strengthen the inner panel Latches will play a very important role. Stiffener pad is the sponge-like material place b/w Inner and outer panel to reduce vibrations.

3.MASTIC DATA:

Mastic Seals place b/w Inner and outer panel to reduce Noise, vibration, and harshness. Every Mastic will have an effect of 80mm Dia locally.

MASTER SECTION FOR HOOD DESIGN

Below we have been given the master section of the hood. Basically we'll take this drawing as the referance while designing the hood.

DESIGN OF OUTER PANEL

The outer panel is the outer skin of the inner panel which is joined to the inner panel by the techniqe called Hemming which is wrapping around the outer sheet metal with the inner panel sheet metal. it is basically a sheet metal joining process. This is done to avoid spot welding which might spoil the outer look.

The thickenss of the outer panel in my design is 0.75mm.

4. Emboss definition: Emboss are provided in the inner panel of the hood assembly. This helps in weight reduction of the hood and also to dissipate the force during collision.

a. Deep Drawing: Deep drawing is a sheet metal forming process in which a sheet metal blank is radially drawn into a forming die by the mechanical action of a punch. It is thus a shape transformation process with material retention. The process is considered "deep" drawing when the depth of the drawn part exceeds its diameter.

b. Hemming: Hemming is a forming operation in which the edges of the sheet are folded or folded over another part in order to achieve a tight fit. Normally hemming operations are used to connect parts together, to improve the appearance of a part and to reinforce part edges.

5. Hood For Better Pedistain Rating:

Inlaid Hood:The line which is drawn 45 deg. from ground to Side Reference of carand which is meeting point on fender is called Inlaid Hood.

Wrap Around Hood: The line which is drawn 45 deg. from ground to front surface of the Hood and which is the meeting point on the outer panel is called Inlaid Hood.

Depending on the Inlaid Hood & Wrap Around Hood we can design hood for head impact in the fig 5.1 shown position of head impactor.

Fig.5.1: Position of head Impactor

HOOD DESIGN

We have the follwing condition

The following class A surface has been given to us :

Now we have added the part as shown below :

Now we will extract the body from the hood outer panel as shown :

We create the first flange refer to master section

create the 2nd flange using through curve to blend the flanges.

LAW EXTENSION

EMBOSS

MIRROR GEOMETRY

SEW

THICKEN

HINGE ASSY

POSITION OF HINGE AND STRIKER

This is determined by measuring the distance between the hinges and drawing a trajectory to see the hood opening and closing. From that take hinge radius for the striker location and draw a circle.

HEMMING OTR PANEL

HEM RELIEF OTR PANEL

RESULT: