Challenge

Hood design-Week 2

SSrota Das25 Aug 2022

OBJECTIVE:

Design Hood outer panel, inner panel and the necessary reinforcements by following the Master section mentioned with the design parameter explained in the videos. Submit an assembly of Hood inner panel, outer panel, latch, hinge and the reinforcements.

The software used for this CATIA V5.

INTRODUCTION:

Safety of Pedestrian : Safety is the most important criteria in automobile designs which concentrates on both pedestrian and occupant safety. The pedestrians are the most vulnerable road users and are at high risk of traffic accidents.

The major reason for the fatality of the pedestrian in traffic accident is due to the head injury resulting from the hard impact of the head against the stiffer hood or the ground. This leads to the necessity of new inner hood panel which is less stiffer and pedestrian friendly.

The fatality of a head injury is based on the head injury criterion (HIC) value. This HIC value is calculated on the basis of the resultant acceleration of the head’s centre of gravity (hereafter called the head centre) during head impacts.

Hood: A hood structure comprises an outer and an inner which form a closed cross section through spaces. The inner's cross-sectional shape is a sine curve, an nth-power-raised sine curve, or a spline curve having a corrugation length approximate to an outside head diameter. This corrugated hood structure can provide a uniform, excellent head impact resistance independently of impact positions on the hood. The corrugated hood structure also excels in tension rigidity, bending rigidity, and torsional rigidity. Accordingly, the car body hood panel structure satisfies requirements of head impact resistances for pedestrian protection and rigidity improvement such as the tension rigidity.

Hinge:Hinge is used as a controlling element for opening & closing of the hood. It connects the hood & engine compartment of car. The hood's hinges serve one other purpose besides holding the hood-safety. In case the hood latch should fail, the hinges are there to keep the hood attached to your car.

Latch: It is used for locking purpose of hood with engine compartment.

Reinforcements : Hood reinforcement structures as provided to reduce impact in collisions & sound absorption.

Embossed Surface : Embossed surface plays an important role in car hood panel while crashing or accident of car. Because during the collision, hood is most affected part which sustains all the impact forces while crashing.

Mastic: The main purpose of the outer panel is for the aesthetic looks. 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. Its also help for NVH purpose.Mastic sealant has the tendency to increase the strength of the panel and has influence of 80mm diameter.

THE MANUFACTURING PROCESS USED IN THE HOOD PANEL ARE:

Deep Drawing:

Deep drawing is a sheet metal forming process in which a 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.

Hemming : Hemming processs is basically used to join the inner hood panel & outer hood panel together.

Hemming metalworking processe in which a sheetmetal edge is rolled over onto itself. Hemming is the process in which the edge is rolled flush to itself, while a seam joins the edges of two materials.

Hems are commonly used to reinforce an edge, hide burrs and rough edges, and improve appearance.

Trajectory:

The latch trajectory is the path which the striker will follow when the hood is open/closed while pivoting on the hinge axis. The latch trajectory is taken as a circle with the hinge axis as the center of the circle. The striker is placed 90 degree such that it is tangent to the circle.

For Hood Design All the steps are mentioned below:

Tool : CATIA V5

Master Data: