Hood design-Week 2

AUTOMOBILE HOOD DESIGN

Here, we'll learn about and create the concept of a front-mounted engine hood in accordance with industry requirements. The hood, often known as the bonnet, is a hinged cover that covers the engine and gives access to the engine compartment or trunk for maintenance and repair.

On cars with front-mounted engines, the hood may be hinged at either the front or rear edge, or it may be split into two portions, one on each side, each hinged along the centerline, as on previous versions. Another option Allows the entire front bodywork to tilt forwards around a pivot near the front of the vehicle by combining the bonnet and wheel arches into one component.

Materials

Hoods are usually made of the same material as the rest of the vehicle's body. Steel, aluminum, fiberglass, and carbon fiber are some of the materials that can be used. To make the vehicle lighter, various aftermarket businesses provide fiberglass or carbon fiber alternatives for steel hoods.

Before we dive into the design, let us understand the rules and regulation standards for 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 places 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 Committee (EEVC), European New Car Assessment Program (euro NCAP)

Pedestrian -Vehicle Collision

• India, however, ranks 1 in the number of road accident deaths across the 199 countries reported in the World Road Statistics, 2018 followed by China and the US. As per the WHO Global Report on Road Safety 2018, India accounts for almost 11% of the accident-related deaths in the World.
• Road transport remains the most favored mode of transport for both freight and passenger movement in India. The fast-growing population, exceptional rate of motorization coupled the ever-growing urbanization has made people vulnerable to frequent road accidents resulting in fatalities, injuries/disabilities.
• the sequence of injuries and events in pedestrian collision images are mentioned below.

Design specifications for the automotive hood component

Master section data was already provided by the support instructors of the course

Data used

Hood thickness information

• Outer panel thickness = 0.75mm
• Inner panel thickness = 0.75mm
• Reinforcement thickness = 1.5mm

the process involved in designing a hood as a sheet metal operation is

• Blanking
• Hemming
• Punch cutting or piercing
• Deep drawn
• Embossing

Design of hood

Inner panel design

• To improve the energy absorption capacity, the hood inner panel must have a high initial response force against the impact imposed on the hood. In a collision, the hood must also reduce the reduction of a response force due to deformation.
• An object of the present invention is to provide a hood inner panel capable of reducing the response force of the hood inner panel even when the level of deformation of a vehicle's hood grows, while also providing adequate energy absorption capacity.
• Only in the inner panel are we able to research and apply pedestrian and motorist safety. Only in this panel may we attach reinforcing, embossing, mastic points, and so on.

Embossing in Sheet metals

• Depending on the sort of embossing desired, metal sheet embossing is generally achieved using a combination of heat and pressure on the sheet metal. The metal thickness is modified in its composition in theory using any of these processes.
• A metal sheet is dragged through male and female roller dies to create a pattern or design on the sheet. Different designs can be created on the metal sheet depending on the roller dies used. The pressure and a mixture of heat "irons" the picture while also elevating the level of the image above the substrate to smooth it out. In contrast to an image dropped into the surface of a material, the phrase "impressive" refers to an image lowered into the surface of a substance.

Deep Drawing

• Deep drawing is a manufacturing technique that is commonly used to shape sheet metal into a cup or box-like forms. Sheet metal deep drawing produces a variety of goods, including cooking pots and pans, containers, sinks, and vehicle parts such as panels and gas tanks. Once drawn, the punch is the desired shape of the part's base. The die cavity is designed to match the punch and is slightly larger to allow for its passage and clearance. The thickness of the sheet metal is believed to be constant in many computations. However, due to the forces involved, there are changes in thickness in particular regions

Hemming

Hemming is a sheet metal manufacturing method that involves bending sheets to 1830 degrees. Hemming procedures are used to create automotive body panels and pieces such as deck lids, trunk lids, doors, hoods, and tailgates.

• For mass manufacturing, traditional die hemming is appropriate. The flange is folded across the full length with a hemming tool in die hemming.
• Roll hemming is done progressively with a hemming roller and is usually the result of a forming operation in which the flange is produced with a hemming tool after the drawing and trimming operations have been completed.
• The hemming roller is guided by an industrial robot, which produces the flange. Pre-hemming and final hemming processes can be separated from the roll hemming operation.
• Using weld or bolts to link the hood panels would compromise the design and aerodynamic aspects, thus hemming is more important to utilize.

Relief points

Mastic

• They can act as fire barriers and provide thermal and acoustic insulation. They could also have electrical qualities. Sealants can also be used for filling and smoothing. They are frequently asked to accomplish multiple of these tasks at the same time.
• A sealant performs three basic functions: it fills a gap between two or more substrates; it forms a barrier by virtue of the sealant's physical qualities and adhesion to the substrate; and it maintains sealing properties over the projected lifetime, service conditions, and environments. These roles are accomplished by the sealant's proper formulation, which results in precise application and performance attributes.

Hood components

Latch

A hood is a pretty straightforward component. It's essentially the fastener that holds your hood in place. This latch keeps your hood securely attached to your car and prevents it from opening suddenly.

By pivoting the secondary latch, which pulls away from a retaining seat positioned beneath the hood, when stress is given to the cable from the hood release handle, the hood is released a few inches before a safety latch takes over.

Hinge

The hinge is a part that connects the hood to the car's fenders. To ensure that the hood opens and closes properly, the latch must be placed perpendicular to the hinge axis.

Latch trajectory motion

The latch must be completely aligned to the fastening or striking point when opening or shutting the hood. The latches' path must be perpendicular to the hinge axis to achieve this.

Impact force distribution in hood design

When a force is impacted on the front of the hood, all of the forces must be deflected outwards from the vehicle. Along with the hood, the force distribution must be adjusted.

Draft analysis

• The inner panel is subjected to the analysis of a 5-degree draft in order to detect any negative drafts. We need to build and submit a positive designs to manufacturers; thus, we're going through this procedure.
• The inner panel shows no negative sketches, indicating that the design is positive and ready to be manufactured.

Hood assembly design