Hood design-Week 2

Hood -

• The Hood/Bonnet is an opening body panel or BiW part, which covers the front of a vehicle
• It covers the engine room in case of the front-engine vehicles and luggage room in rear-engine ones
• A hood is similar to a door

Commonly used materials in Hood -

• These materials are selected based on the required properties -
• Steel
• Aluminium
• Magnesium
• Composite materials
• Desired Properties -

• Strength, Manufacturability, Availability, Cost, Chemical or Mechanical resistance, durability etc.

Components of Hood -

• Hood Outer Panel
• Hood Inner Panel
• Hinge Reinforcement (LH)
• Hinge Reinforcement (RH)
• Latch Reinforcement
• Hood Stiffener

Hemming -

• Hemming is a process of joining the sheet metal parts together by bending a sheet over another
• The flange which forms after bending is called a Hemmed Flange or Hem Flange. There are various types of 

HemSafety Standards -

• NCAP - New Car Assessment Program - Created in 1979 by the US National Highway Traffic Safety Administration. It was put into practice in order to produce better and safer vehicles
• Every car follows a set of standards
• Regions (except Global NCAP) -
• Bharat - NCAP
• European - NCAP
• Japan - NCAP
• British - NCAP

Pedestrian Safety -

• Pedestrian Head Impact
• Wrap-Around Distance (WAD)
• Under Bonnet Clearance
• Head Form Test Method

Wrap Around Distance -

• Distance which is traced by a line which goes from the ground to the end point of contact.
• Child - 1000mm to 1500mm
• Adult - 1500mm to 2100mm

HIC - Head Injury Criterion :

• HIC is the value on the basis of which the safety rating for head impact is determined.

• a = Resultant accl. Measured in units of gravity
• t1 and t2 = Time considered during A-3 ms
• A-3 ms = Maximum force that lasted for 3 ms

• Data considered during HIC -
• Event Duration - 100 to 250 ms
• Instances duration - 35 to 45 ms
• Instances are taken considering A-3 ms