Hood design-Week 2

CAR HOOD DESIGN Using NX

Aim: To design car hood in NX using given master section and provided design parameters.

Hood and its components:

1. Hood:

Car hood/bonnet is a hinged cover that rests over the engine in a front-engine car. A latch is provided under the hood in order to prevent accidental opening during driving. Purpose of hood is to provide access to the engine and battery for repair and maintnance. It also protects for repair and maintenance. It also protects these parts from direct sunlight and dust.

2. Components-

The car hood consists of following components.

Hood outer panel:

The outer panel works as a metal cover. It is resposible for aesthetics of the vehicle.

Hood Inner panel:

The inner panel provides strength and supports the outer panel. It is where hood balanccr and hinges are attached.

Hinges:

Hinges allow the hood to rotate around a fixed axis for opening and closing movement. One part of the hinge is fixed with the engine compartment, while other part is connected to hood.

Assembly:

Latch and stricker-

Latch and striker mechanism is provided to lock the hood, in order to prevent accidental opening of the hood during driving. The latch is present on the engine compartment while the striker is attached to inner part of hood.

Support Rod-

It is a device that support the hood in open position. It is also called as hood balancer rod.

Reinforcement-

The reinforcements are provided to add material to the inner panel to provide extra strength to the hood to compensate for loss of strength near component installation regions.

Latch Trajectory-

It is the path along which the hood rotates during opening and closing movement. The striker on the hood follows a particular path while opening or closing the hood, Which is along circumference of a circle with center at the hinge axis. This path is nothing but latch trajectory. It is a very important aspect in hood design, in order to decide hinge, latch and striker installation points.

Design Methodology:

The procedure followed for designing the hood and its components is as follows,

- First the inner panel is designed from the given master section using the various commands and features. We create the embossing using the offset surface from the original master section. Similarly, we create the cuts on the emboss by sletching and using trim surface option.

- Then the outer panel is designed from the same master section, Here we are supposed to provide the hemming to outer panel. The parameters of hemming are taken as per given values.

Hemming-

- Now on the inner panel, the embossing for hinge and striker are produced by considering their respective dimentions and assembly positions. First the emboss for hinge is created and then by fixing the hinge into its positions, we draw an axis passing through both side hinge axes to form a common axis. And then we position the striker such that it will move along circumference of a circle whose center is at midpoint of the common axis. Thus , position of striker is decided and we can create emboss for the same.

- Data provide-

Outer panel Thickness - 0.75mm

Inner panel Thickness - 0.75 mm

Reinforcement Thickness - 1.5 mm

Important features used in designing:

• Trim Body - It is used to trim one or more bodies using a face or plane. You can also specify the bodies to retain and the bodies to discard.
• Offset surface - It allows you to offset one or more existing surfaces.
• Offset in face - This command will allow you to offset particular edges or curves on selected faces.
• Trim sheet - It is used to trim off a portion of a sheet body using curves, faces, edges, planes.
• Through curves - It will allow you to create a body through multiple sections, where its shape changes to pass through each section.
• Law Extention - This command extends a curve or edge to create a sheet body at desired angle length by changing the rules under angle law and length law.
• Trim and Extend - It helps you to trim and extend intersecting surfaces and make cornor at their intersection.
• Face Blend - It creates fillets between faces
• Edge Blend - It creates fillets on edges.
• Extend sheet - It will allow you to extend an existing surface to required distance.
• Emboss - Emboss command creates an embossing by modifying a body with faces created by projecting a curve/section along a direction. You can modify the emboss using options like endcap location and draft angle.
• Projected curve - It is used to project an existing curve/curves on a selected plane or surface by selecting a direction for projection.
• Mirror Geometry - As name suggests, it allows you to mirror geometries about selected plane or surface.
• Sew - It combines sheet bodies together by sewing their common edges. There shouldn't be any gaps larger than specified tolerance.
• Thicken - It is used to convert a surface to solid body by providing thickness.
• Extrude - It helps you to create a feature from a sketch. You are also able to create thin feature using a sketch or curve under this command.
• Wave Geometry Linker - With this you can create, associative or linked copies of any entity of a part into other parts. It may be a surface, edge, curve, body, sketch etc. The changes made to the original entity will be reflected in the copy of that entity.

Conclusion:

I designed the car Hood along with its components and assembled the same, using NX CAD, under given parameters.

Google link:https://drive.google.com/file/d/1ydFH2DvwVga0_vMydHfcBh4yCIMVKtWo/view?usp=sharing