Body and Chassis

Question 1

Mass Volume

Answer 1

Over 250,000 per annum
Unitary BIW in advanced steels

Question 2

Mid Volume

Answer 2

Below 50,000 per annum
Materials: Steel, aluminium, composite

Question 3

Niche/ Low Volume

Answer 3

Less than 10,000 per annum
Materials: Carbon composite, aluminium or steel

Question 4

Longitudinal Load cases

Answer 4

IIHS front 40% ODB, NCAP front impact, FMVSS 301 rear 70% ODB

Question 5

Two Lateral Load cases

Answer 5

IIHS side impact, FMVSS 214 pole impact

Question 6

One vertical load case

Answer 6

FMVSS 216 roof crush using the IIHS four-times strength-to-weight ratio

Question 7

Zones

Answer 7

Rigid High strength structural passenger cell and ductile ‘crumple zones’ to absorb impact energy

Question 8

Torsional Structural Requirement from ULSAB 1996

Answer 8

Industry benchmark 11,500 NM/deg (8,000 -14,500 Nm/deg) with glass
Torsional Stiffness / mass (Ct/m) average 44, range 30-60 most 40-50 (Nm/deg)/kg

Question 9

Bending Stiffness Requirement

Answer 9

Industry benchmark - 12,000N/m (8,000 - 14,500 N/m)
Bending Stiffness/mass (Cb/m) average 45 range 25-60 (Nm/m)/kg

Question 10

Resonant Frequencies

Answer 10

Industry Benchmark - 38Hz (34-45Hz)

Question 11

BIW usage

Answer 11

Used on modern mass volume vehicles. Steel blanks of various grades (140MPa – 900MPa) and thicknesses (0.6- 2mm)

Question 12

BIW production

Answer 12

Highly automated processes highly capital and volume intensive
Steel blanks are laser
welded together. Typically the steel is zinc coated on both sides to add anti-corrosion
coating.
2D blanks are press formed into 3D panels
3D panels are robotically located in fixtures and resistance (spot) welded together to make
substructures.
Substructures are robotically assembled in jigs and fixtures and resistance welded to make
BIW

Question 13

Benefits of Laer/tailor welded approach

Answer 13

Different steel grades can be used in different areas of the vehicle to meet the requirements of that zone and allows engineering freedom

Question 14

Ladder Frame

Answer 14

Steel frame that sits on top of the wheel base. Typically used in the US pick-up truck market

Question 15

Space frame

Answer 15

Series of metal tubes put together to create structure. Typically steel and used in component cars such as Caterhams

Question 16

Monocoque

Answer 16

Mostly used in the supercar market formed of a carbon fibre tub with either an Aluminium or Steel subframe

Question 17

Component Masses by material

Answer 17

Current steel 400kg
Optimised can give 10-20% decrease
Aluminium up to 40% reduction
Magnesium 50%
CFRP 60%
The reduction in weight however is relative to the material cost

Question 18

Steel Costs

Answer 18

£383 per tonne

Question 19

Aluminium Cost

Answer 19

£1,340 per tonne

Question 20

Carbon Fibre Cost

Answer 20

12,900 per tonne

Question 21

Mass of BIW

Answer 21

Benchmark for a mid sized vehicle was 270kg (240kg - 320kg) however moder crash requirements have increased this to 310kg

Question 22

Use of the Platform Concept

Answer 22

Having many cars following a similar platform allows components (drivetrain, seats, electrics, etc) to be shared across different vehicles with different BIWs