Hood design-Week 2

Hood Design-

Objective- To design Hood or Bonet of a car by referring given master section and standard procedure which is used in OEM manufacturer's.

Software used- Catia V5.

Given Master Section-

The following tasks are performed-

• Develop the inner panel Providing the proper embossing.
• Develop the outer panel with hemming data.
• Providing mastic data
• Positioning all the reinforcements.

Data to be used-

• Outer Panel Thickness = 0.75mm

• Inner Panel Thickness = 0.75mm

*Reinforcement Thickness 1.5mm

HOOD-

The car's hood consists of an inner and an outer panel. The inner panel provides strength, while the outer panel is just a metal cover. The underside of the hood is often covered with a sound-absorbing material. Some high-performance cars have 'hood scoops' which channel outside air directly to the air filter, which gives improved performance and efficiency.

Pedestrian Safety :

People and vehicles often share the road, especially in densely populated areas. In a fast-paced world with many distractions, the reality is that pedestrians and vehicles are involved in accidents with severe or fatal injuries as a result. Vehicle safety factors should simultaneously consider occupant and pedestrian safety, given that pedestrians are the third-largest category of traffic fatalities. Most pedestrian deaths occur due to traumatic brain injury, resulting from the hard impact of the human head against the vehicle's stiff hood or windshield. Therefore, how to design a pedestrian-friendly vehicle propose a new hood structure is a matter of urgency for minimizing pedestrian head and injuries. In this study, three kinds of sandwich hood structures are proposed for reducing pedestrian head injuries, including carbon fiber-reinforced polycarbonate , carbon fiber reinforced foam and aluminum-reinforced polycarbonate.

Deep Drawing-

For steel deep drawing is used. Deep drawing is one of the most widely used processes in sheet metal forming. Apart from its use in many other sectors, it is applied in the automotive industry for the manufacturing of car body parts. The deep drawing process is a forming process that occurs under a combination of tensile and compressive conditions. 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. This is achieved by redrawing the part through a series of dies. The flange region ( sheet metal in the die shoulder area ) experiences radial drawing stress and tangential compressive stress due to the material retention property. These compressive stresses ( hoop stresses ) result in flange wrinkles. Wrinkles can be prevented by using a blank holder, the function of which is to facilitate controlled material flow into the die radius.

Designing of Hood in CATIA V5 software-

Inner Panel creation-

Here we will work on half part of the master section and then mirror it.

Creation of Emboss-

Emboss is created to for compensating the removal of material.

Emboss is created in such a manner that it will change the direction of the impact force towards the hinges and also crumbles that will reduce the impact for the passenger

Mastic point-

Mastic points are areas where the inner hood panel is joined with the outer panel using mastic glue. This mastic glue keeps the inner panel stuck to the outer panel. The main purpose of the outer panel is for the aesthetic look. Thus, we cannot use rivets or spot welding. This has to be done with the help of the hemming and mastic sealants. Mastic sealants are elastic compound that behaves like rubber. It is placed between the outer and inner panel. Initially is it in paste form but after the hot furnace bath, it gets hardened thus joining the outer and inner panel.

Creation of profile of Mastic Points-

giving 0.75mm thickness to inner panel.

Creation of Outer Panel-

Given relief all corners-

giving 0.75mm thickness to outer panel.

The most important factor in the hood of the car is the trajectory of stricker. If it does not properly design, then fitting of the hood will create a problem.

Hemming-

Hemming is a sheet metal forming process in which sheets are joined by bending them to 180 degrees. Automotive body panels and automotive parts such as deck-lids, doors, hoods, and tailgates are formed by the hemming process, in this process usually, a sheet is bent with the help of the inner and outer sheets. hemming is formed in which the edge of the sheet is folded over another parting to achieve a tight fit. Roller hamming process

Pros-

To fasten two sheet metal parts by folding the edge of the sheet back on itself.

Types of hemming

• Rolled hemming

• Closed hemming

• Teared drop hemming

• Open hemming

Draft Analysis on Inner panel-

Multi View of Hood-

Exploded View-