Hood design-Week 2

AUTOMOBILE HOOD DESIGN

Introduction:- We are going to understand and design, the concept of front mounted engine's hood accourding to the standards. The hood or bonnet is the hinghed cover over the engine of motor vehicle that allows access to the engine components or trunck for maintenance and repair. On front mounted engine car, the hood may be hinghed at either the front or the rear edge or in earlier models, it may b split into two section. One each side, each hinged along the centreline. A further variant combines the bonnet and wheel arches into one section and allows the entire front body work to tilt forwards around a pivot near the front of the vehicle.

Materials Used:- Hoods are typically made of the same material as the rest of the bodywork. This may include steel, aluminium,fiber glass or carbon fiber. However, some aftermarket companies produce replacements for steel hoods in fiberglass or carbon fiber to make the vehicle lighter.

Rules and Regulation standards fir designing the hood:-

• A perfect hood design means it should have a great impact distribution angled outside the car.
• In japan and europe regulations have come into effect that placed a limit on the severity of pedestrian head injury when struck by a motor vehicle. This is leading to more advanced hood designs as evidenced by multicore hood inner panel designs.
• European enhanced vehicle safety committe (EEVC), European New Car Assessment Program( Euro NCAP).

Pedestrian Vehicle Collision:-

• India, However rank 1 in the number of road accident death across the 199 countries reported in the world road statistics 2018 followed by chine and the USA. As per the WHO globle report on road safety 2018, India accounts for almost 11% of the accident related death in the world.
• Road transport remains the most favored mode of transport for freight and passenger movement in india, The fast growing population, exceptional rate of motorization coupled with the ever growing urbanization has made people vulnerable to frequent road accidents resulting in fatalities, injuries or disabilities.
• Some images give below that are consider while desinging hood

Design Specifications for the Automotive Hood Componets:- Master Section data was already provided by the support instructions of the course.

• Outer Panel Thickness - 0.75mm
• Inner Panel Thickness - 0.75mm
• Reinforcement Thickness - 1.5mm

Process Involved in designing Hood:-

• Blanking
• Hemming
• Punch Cutting or Piercing
• Embossing

HOOD COMPONENTS

Hood Outer Panel:- A hood panel consists of two panels that are hemmed together to form the automotive hood assembly. The inner panel of the hood is not visible to the customer but this is the engineering feature of the outer panel. The outer panel has the aesthetic look to it but on its own is very weak and not capable of handling force during impact.The outer panel has the aesthetic look to it but on its own is very weak and not capable of handling force during impact.

• Most automobile hood outer panels are made of traditional steel plates, and their quality does not meet the needs of lightweight development. For this reason, it is necessary to obtain lightweight effects through the application of the automotive aluminum sheets.

Hood Inner Panel:- The hood inner panel is reqired to have a high initial reaction force againt the impact extend on the hood to enharance the energy absorption capacity. The hood is further required to minimize a reduction of a reaction force by deformation in a collision.

• It is an object of the present invention to provide a hood inner panel capable of reduction of a eaction force of the hood inner panel even if a level of deformation of a hood of a vehicle increase and ensuring a sufficient enery absorption capacity.
• In the inner panel only we can research and implement the safety of pedestrians and as well as the driver in this panel only we can attach the reinforcement, embosse, mastic point etc.

Latch:- A hood latch is a very simple componet. it's basically the fastener that keep your hood closed shut. This latch ensure that your hood is securely connected to your vehicle and that it doesnot pop open unexpectedly when tension is applied to the cable from the hood release handle. it pivotes the secondary latch , which pulls away from a retaining seat located latch then releases the hood a few inches before a safety latch take over.

Hinge:- Hinge is a component that fixes the hood to the fenders of the car. The latch must be fixed perpendicular to the hinge axis so that the hood opens or closed properly.

TECHNICAL TERM USED DURING HOOD DESIGN

Embossing in sheet metal:-

• The metal sheet embossing operation is commonly accomplished with a combination of heat and pressure on the sheet metal, depending on what type of embossing is required. Theoretically with any of these procedures, the metal thickness is change in its composition.
• A metal sheet is drawn through the male and female roller dies, producing a pattern or design on the metalsheet. depending on the roller dies used, different patterns can be produced on the metal sheet. The pressure and a combination of heat actually 'irons' while raising the level of the image higher than the substante to make it smooth. The term impressing refer of an image lowered into the surface of a material in distinction to an image raised out of the surface of a material.

Deep Drawing:-

• Deep drawing is a manufacturing process that is used extensively in the forming of sheet metal into a cup or box like structures. Pot and pans for cooking , containers, sink, automobile parts such as panels and gas tanks are among a few of items manufacturing by sheet metal deep drawing.
• A deep drawing of sheet metal is performed with a punch and die. The punch is the desired shape of the base of the partonce drawn. The die cavity matches the punch and is a little wider to allow for its passage as well as clearance. For many calculation, the sheet metal thickness is assumed to remain constant. However , there are changes in thickness in certain ares due to the forces involved.

Hemming:-

• Hemiming is a sheet metal forming process in which sheet are joined by bending. It usually to 180 degree. Automotive body panel and automotive parts such as deck-lids, trunk-lids, doors,hood and tailgates asre formed by hemming process.
• Conventional die hemming is suitable for mass production. In die hemming, the flange is folded over the entire length with a hemming tool. Normally the actual hemming is a result of a forming operation in which the flange is formed with a hemming tool after the drawing and trimming operations have been completed.
• Roll hemming is carried out incrementally with a hemming roller. An industrial root guide the hemming roller and forms the flange. Roll hemming operation can also be divided into several pre-hamming and final hamming process steps.
• If weld or belts were used to join the hood panel then the design and the aerodynamic feature would get damaged so hemming is more significant to use.
• While doing the hemming process, a relief angle is formed as a product of hem when attaining at the corner of the sheet metals.

Mastic data:-

• A mastic sealant data is used to fix or combine the hood outer panel and hood inner panel.
• They can provide thermal and acoustical insulation and may serve as fire barriers.They may have electrical properties as well. sealer can also be used for simple smoothing or filling. they are often called upon to perform several of these function at once.
• A sealant has three basic function-1.)It fill a gap between two or more substrates.2)It forms a barrier through the physical properties of the sealer itself and by adhesive to the substrate. 3) It maintains sealing properties for the expected lifetime service condition and environments.

Latch Trajectory Motion :-While opening or closing the hood, the latch must be perfectly aligned to the fixing or striker poin. For that, the latch trajectory must be perpendicular to the hinge axis.

Impact Force Distribution:-A hood design must be made in such a way that when a force is impacted in the front of the hood, all the force must be directed outwards from the vehicle and the distribustion of the force must be controlled along with the hood.

Draft Analysis:-

• 7 Degree draft analysis is made to the inner panel to find any negative draft. this process is done because we need to develop and submit a positive design to the manufacturers.
• We can see that there no negative draft by the inner panel, hence the design is positive and ready to manufactured.

Isometric View

Top View

Front View

Side View

Conclusion:- Therefore, we have designed a hood that falls under the rules and regulation of the manufactures's standards.