Hood design-Week 2

DESIGN OF HOOD ASSEMBLY

OBJECTIVE

Design Hood outer panel, inner panel and the necessary reinforcements by following the Master section mentioned with the design parameter.

CONTENTS

1. Introuduction

• Design Guidelines

• CAD Design

• Conclusion

Introduction

Hood is one of the primary BIW Closure Component , it serves as a Cover for the Engine compartment and can be opened for maintenance or servicing of the Engine , battery and other Driveline Components.

It primarily Consist of Hood Outer Panel , Hood inner Panel , Latch and Striker , Reinforcements for Latch and Striker, Support rods.

Outer Panel is a styling surface and has lots of aesthetic and gap and flushness requirements to be met for designing , Inner Panel is designed using the outer as a master considering the interface with Latch , Striker , Hemming , Mastic requirements.

Both Combined together are designed for meeting pedestrian requirements primarily and designed to divert the force from frontal collision towards the Side Pillars.

2) Design Guidelines

Hood is a critical closure BIW Component and has lots of regulatory and Safety requirements to be considered before starting the design. Few of them are listed below.

*Head Clearance.

This requirement is different for different regions around the word , depending on the average height of individuals.

Based on the distance C and D as observed from the graph the correct opening angle can be inferred which helps in deciding the position of Striker and Latch also.

*Wrap around Distance

The Wrap around distance is an important criteria in design of the inner panel , Its a measurement of distance from Ground to the head impact zone and is different for different individuals.

*Support Rod and Gas stay.

Support rod and Gas stay are two different ways by which the hood is held in open condition

Gas stays are Semi Automatic and once the hood is slightly open , the hydraulic mechanism lifts the hood completely without any other effort. Gas stays require more strong designs and additional reinforcements compared to a normal support rod which is manual.

Support Rods are manual bent rods which are attached to engine compartment on one side and to the hood using a hook type mechanism to support the hood in open condition.

CAD Design

Input Parameters:

Hood Outer Thickness: 0.75mm

Hood Inner Thickness: 0.75mm

Reinforcement Thickness: 1.5mm

Final Design:

Mastic Locations

Hood Opening Trajectory.

For Proper Opening of Hood the Striker should be perpendicularly placed , this is done by Creating a trajectory for the hood hinge and the striker is aligned tangentially to the trajectory.

Hemming Relief.

Hemming is an operation used to join inner and outer panel together by folding the inner panel on the outer using hemming rollers.

Since the Rollers cannot cover the entire edge in one Single Pass , multiple rollers and multiple passes are involved which requires a relief to be provided in the corners for easy bending of the inner panel.

Deep Drawing process is used for manufacturing of sheet metal parts , which consist of Die , Punch and Binder.

The material used varies depending on the Formability and strength requirements mostly High strength steels or Deep drawing steels are used due to the complex shape of Inner Panel.

Conclusion:

Hood Assembly is designed using all required parameters and considering all regulations.