Challenge

Hood design-Week 2

YYogesh S2 Jan 2023

HOOD DESIGN

AIM

Design outer panel with the hemming process and develop the Inner Panel, create all the needfull Reinforcements, Mirror and position the Hinge & Striker using tragectory method, provide Mastic Data, and provide the required Emboss height considering the thickness and mastic.

WHAT IS HOOD

Hood is an main part in the front portion of the car which is used for many purposes. It is made considering the aerodynamic in shape to reduce air drag. Generally, it is used to cover car engines, radiators, and many other components, the design must meet pedestrian's requirements and design should be satisfying and also design should be made in a way that when an accident occurs the impact energy should not reach the people inside the car.

DESIGN DIMENSIONS

Outer Panel Thickness = 0.75mm
Inner Panel Thickness = 0.75mm
Reinforcement Thickness = 1.5mm (0.75+0.75)
Minimum fillet radius - 3.75 mm
No sharp corners inside the component
A minimum draft angle of 7 degrees

FUNCTION OF HOOD

Bonnet is also called hood in US and CANADA. It is hinged,hemmed thin sheet which covers and protects the main parts of car like engine.

Its main function is to direct access to the engine, battery and other critical parts of the car for repair and maintenance and to protect these parts from direct sunlight and dust.

EURO NCAP Test

EURO NCAP Test is performed to check the safety of pedestrians by considering head impact, leg impact, etc.

Head Impact Injury Criteria

COMPONENTS IN HOOD:

OUTER PANEL

INNER PANEL

HINGE

STRIKER

ASSEMBLY

SUPPORT ROD

Support rods are designed by providing embosses and holes on them to avoid bending of the rod as compared with straight support rods.

DESIGN PROCEDURE/DESIGN FLOW CHART:

INNER PANEL

The hood inner panel is required to have a high initial reaction force against the impact exerted on the hood to enhance 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 reaction force of the hood inner panel even if a level of deformation of a hood of a vehicle increases, and ensuring a sufficient energy 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, embossed, mastic points, etc.

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 changed in its composition.

A metal sheet is drawn through the male and female roller dies, producing a pattern or design on the metal sheet. 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 substrate to make it smooth. The term "impressing" refers to 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. Pots and pans for cooking, containers, sinks, automobile parts, such as panels and gas tanks, are among a few of the items manufactured 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 part, once drawn. The die cavity matches the punch and is a little wider to allow for its passage, as well as clearance. For many calculations, the sheet metal thickness is assumed to remain constant. However, there are changes in thickness in certain areas, due to the forces involved

HEMMING IN SHEET METAL

Hemming is a sheet metal forming process in which sheets are joined by bending it usually to 180°. Automotive body panels and automotive parts such as deck-lids, trunk-lids, doors, hoods, and tailgates are formed by hemming processes.
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 robot guides the hemming roller and forms the flange. Roll hemming operation can also be divided into several pre-hemming and final hemming process steps.
If weld or bolts were used to join the hood panels then the design and the aerodynamic features 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

WHAT IS MASTIC?

This material has the task of filling the irregularities that may occur between two surfaces by isolating the junctions of materials of the same or different nature. Mastics can also fill cracks in surfaces such as concrete, fiberglass, and other hard building materials. It can also be used outdoors as it is resistant to water, heat, and UV rays.

They can provide thermal and acoustical insulation, and may serve as fire barriers. They may have electrical properties, as well. Sealants can also be used for simple smoothing or filling. They are often called upon to perform several of these functions at once.
A sealant has three basic functions: It fills a gap between two or more substrates; it forms a barrier through the physical properties of the sealant itself and by adhesion to the substrate; and, it maintains sealing properties for the expected lifetime, service conditions, and environments. The sealant performs these functions by way of correct formulation to achieve specific application and performance properties.

HOOD COMPONENTS

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 closes properly.
The hood hinge is a pivot and bracket mechanism that makes it possible for you to open and close your hood. Each car typically has a pair of hood hinges installed in the front of the vehicle.

STRIKER

A hood striker is a very simple component. It's basically the fastener that keeps your hood closed shut. This latch ensures that your hood is securely connected to your vehicle and that it doesn't pop open unexpectedly
When tension is applied to the cable from the hood release handle, it pivots the secondary latch, which pulls away from a retaining seat located under the hood. By design, the secondary latch then releases the hood a few inches before a safety latch takes over.
It is attached to the hood and is used to keep the hood panel in the lock position.

Hood Latch Striker is designed for long-lasting use. Its durable steel construction safeguards against body damage, ensuring the vehicle hood won't unexpectedly open while driving.

REINFORCEMENT

Reinforcements are the support given to hinge and latch emboss as direct forces act onto it. To provide extra strength reinforcements have been provided.

TRAJECTORY MOTION

WHAT IS TRAJECTORY MOTION?

The trajectory is the curved path of an object in relation with motion along with the gravity. It can also be called as projectile motion. In simple words, it is the curved path of an object under the gravity. The example of trajectory will br a ball thrown uwards, the path taken by the ball is determined by the gravity and resistance of air.