Hood design-Week 2

HOOD DESIGN - NX

Objective-Designing of hood outer panel, inner panel and reinforcements with the given outer hood skin, master section and design parameters using nx.

Introduction-The hood or bonnet is the hinged cover over the engine of motor vehicles.Hoods can open to allow access to the engine compartment, or trunk on rear-engine and some mid-engine vehicles for maintenance and repair.A typical hood assembly consist of hood outer panel, inner panel, latch and striker, hinge, hood stay. Hood stay is an apparatus for supporting the engine hood of a moto vehicle in its open position. The purpose of opening the engine hood is for inspecting engine room, replenishing cooling water and engine oil, changing parts and making repairs etc.

DESIGN DATA-

Hood Thickness Information

Outer Panel Thickness=0.75mm

Inner Panel Thickness=0.75mm

Master section-

DESIGN PARAMETERS

Outer panel-

Outer panel is the outer cover for engine and it is used to make car more finished and protects the inner parts.

Inner panel-

The inner panel supports the outer panel. it consists of embosses & holes. Embosses provide stiffness as well as it dissipates energy towards reinforcement.

Hemming-

The outer panel & Inner panel can't be joined by any welding process if we did it will leave a spot on the outer panel and it will effect the car's finishing. so, to join inner and outer closure panels together we use the Hemming process.It is the process of bending/folding the flange of the outer panel over the inner one.The flange of the outer panel is bent over the inner panel in progressive steps by means of the roller hemming head.the gaps used for hemming is 0.2mm and thickness given is 0.75mm.

Corner Relief-
The corner relief is used on the hemming part. In this process the roller will be rolling over the edges of the Outer panel to close it with the inner panel. These roller will be rolling over 2-3 time for perfect closing. when the rollers could not be tighten we need to use corner releif.the process can be done by bridge curve or curve on surface tools.

Mastic sealant-
The Mastic sealant or mastic points is a elastic compound that behaves like a rubber. it is applied between Hood's outer panel and inner panel. it have an influence area of about 50mm.

Reinforcements-
The reinforcements used are-

• Latch & striker
• Hinge

they both are used to give more strength to the assembly.Latch & striker is used for locking the hood with the car. it's usually placed on the space provided on the inner panel.Hinges are used to connect the hood & cowl panel of an automobile. it enable the opening & closing operation of the hood. the hinge should be made strong enough to to handle the weight of the hood and also to handle the force action on it during the collision.

Position of Hinge & Striker:-

The hinges should be usually placed on both sides of the hood in such a way that the strike fits exactly into the hole provided.Both the hinges should be on the same axis.The centre of the striker's circular trajectory should be always perpendicular to the hinge axis.

Emboss:-
They are the projections made on sheet metal using deep drawing techniques. the operation is carried out the mostly for the purpose of stiffening flat surface and design in the inner panel. the major function of embossing is to dissipate the force acting on the hood during the collision of the car toward the hinges as early as possible. this helps to reduce the impact of the force on the passenger sitting inside.thus the safety is enhanced by this process.

Draft analysis:-

after the design fully developed, the inner panel of the hood is anaylzed for manufacturability. here draft analysis shows that all parts are clearing when core is removed from cavity.thus it is eligible for manufacturing.

Conclusion-

All the parts are designed as per the requirements and based on the given dimension.with completion of the hood design succesfully its can be forwarded for manufacturing and

can be used for vehicles.here the safety of both the occupant and the pedestrian is taken to consideration which is designed based on euroNCAP safety regulations.