Page 582 - Automotive Engineering Powertrain Chassis System and Vehicle Body

18.1
Chapter 18.1

Design and material utilization

Geoffrey Davies

had to respond to a series of different outside influences
OBJECTIVE
among them legislation on safety, emissions control and
To briefly review the historical development of the recycling. Thesehaveresultedinsomeconflictingresults,
automotive body structure before considering how mate- for while weight reduction and use of lower density mate-
rials have helped to realize engineering and associated rials have extended the choice the increased variety and
objectives. Specific examples are selected to illustrate particularly the use of some plastics have caused additional
the changes that have taken place in the selection of steel headaches for the dismantling industry.
grades, the emergence of aluminium and the increasing After a consideration of milestones in autobody design
trend to hybrid material combinations. through the last 100 years, the rationale of the modern
designer is introduced with an example (from BMW) of
CONTENT how this is influenced by material choice. Examples are
then given of alternative approaches to design using
A brief outline is given on the evolution of various design
lightweight alternatives to steel, the traditional choice.
concepts and materials utilization – reference is made to
Reference is made here to broader initiatives such as the
specific examples, where relevant changes have been
major aluminium programmes (ECV, ASVT) and steel
made – the criteria typically used in optimizing design
(ULSAB), which have demonstrated the feasibility of the
using FEM are defined – the utilization of coated and high newer technology. The spin-off from these background
strength steel (HSS) grade are introduced – alternative ‘enabling’ projects has been adopted in many parallel
body architecture is considered – use of aluminium and model programmes in recent years and this is self-evident
other lightweight materials are referenced together with in some of the instances given in this chapter. The same
the use of hybrid structures.
applies to many international initiatives (e.g. BRITE
1
LightWeightVehicleProgrammeBE–5652 )plussupplier/
18.1.1 Introduction user projects which have provided increased confidence
in longer range concerns, and although the immediate
While highlighting significantdevelopmentsinthe design pay-off from these programmes is not always immediately
architectureoftheautomotivebodystructure,theemphasis obvious it is critically important that funding for these
of this chapter is more concerned with the selection and general ‘feeder’ activities continues.
use of materials, and how engineers have utilized relevant
properties to satisfy their selection criteria over a timescale 18.1.2 Historical perspective and
which now covers at least 100 years. Early materials selec-
tion was fairly limited and chiefly dictated by cost as the evolving materials technology
demands of mass production grew. Later availability became
an issue, as two world wars had a draining effect on re- The progess made in the development of engineering
sources. But perhaps the period of greatest interest has structures over the last century has been dealt with ex-
spanned the last 30 years. During this time engineers have pertly elsewhere 2 and with regard to recent model
Materials for Automobile Bodies; ISBN: 9780750656924
Copyright Ó 2003 Elsevier Ltd; All rights of reproduction, in any form, reserved.