Hood design-Week 2

AIM:

To design the inner panel of the hood. The inner panel of the hood gives strength to the hood outer panel and helps for safety purposes both pedestrian and crash. We also design the assembly of the hinge and the striker components.

THEORY:

A Hood is a cover used to protect the engine Assembly from any external damage. Also, it is an important feature for pedestrian safety guidelines. Steel and aluminium are some of the common material used to manufacture the component but in high-end sports vehicle, high quality plastic materials are also used.

The hood consists of 2 parts an outer and an inner panel. The Outer panel is for aesthetics purpose. While the inner panel provides support and required strength for passenger safety. The inner part of the hood is joined with the outer panel through a process called hemming. The hood part must be designed in such a way that the force distribution during the collision is outside the body and very minimal force reaches to the passenger cabin.

The hinge and the striker are the components which provide and restrict the motion of the hood the angle at which it can open and the point at which it is going to be locked.

DESING CONSIDERATIONS:

There are two things to keep in mind: Always follow the codes for the country/region that the control panel is going to. Use good, common sense. Simply following codes is only part of the art of designing control panels. A neat, nicely laid-out control panel is very important.

It is very important to consider all the said safety and quality features for the any part of the car to be made and every country has their own way of making a detailed description of the panel safety according to the heights and other restrains of the geometrical and biological complications of the region.

DESINGING OF INNER PANNEL:

Master Sketch:

Data to be used:

Hood Thickness Information

• Outer Panel Thickness=0.75mm
• Inner Panel Thickness 0.75mm
• Reinforcement Thickness = 1.5mm

Inner panel:

Inner panel supports outer panel. It consists of different embosses and hole at different places. Embosses provide stiffness as well as dissipate energy towards hinges. To determine the most effective position of hole, the method of modal stiffness is employed. Inner panel is offset of the parent work surface. Inner panel thickness is 0.75mm.

One of the most basic requirements to make emboss on the inner panel is to minimize the pedestrian crash impact specifically on the head. This is why the centre part is of the inner panel is cut out and made so that it can crumble on heavy impact there are small embosses at the extreme outer edges so that the hood crumbles outwards in an inverted v shape and reduce the damage in the driving compartment to minimum.

Outer panel designing:

Design of Outer panel -

• The outer panel is a cosmetic part but it has an important purpose of protecting the engine part assembly from environmental damages
• Hemming is used to combine the inner and outer panel
• Front and end relief is provided during hemming to reduce stress concentration at the corner

0.75 mm thickness is provided

• The outer panel is a styling part so it is generally developed inside OEM's facility

Hemming feature on the outer panel.

Positioning of hinge and striker assembly:

For positioning hinge and striker, we have to place hinge tentatively and take hinge axis point and place position from data taken from the parent car or our own. The other major functional of the hood is the opening and closing of the hood. This is done with the help of the latch and striker. To position the latch and striker effectively, we position the hinge and draw the hinge axis: Now, using the hinge axis as the centre we draw a big circle to the position where we need the latch to be placed. Then, we draw a tangent line to the circle at that point and place the latch in that region.

Final assembly:

The emboss of the latch and striker component is made by using the Law extension feature and that of the hinge component is made by sketching on a parallel datum plane as described in the positioning of both parts.