Automobile Materials
SRJC - ENGR 45 Semester Project (Fall ’09)
Brian Goff
Mario Grasso
Oscar Briceno
Some Background...
Cars at first were built entirely of wood, and later of
wood frames with steel body panels.
In the early 1900’s, the idea of a body-on-frame
design came about.
These vehicles had
a load-bearing chassis
that supported all the
mechanical parts
and a body usual made
of steel.
Ford Model T
Courtesy Car Body Design
http://www.carbodydesign.com/articles/2005-04-13-chassis-history/2005-04-13-chassis-history.php
Moving Forward...
Honda Civic Frame
http://automobiles.honda.com/images/2009/civic-sedan/safety/safety-header.jpg
Today, most smaller
vehicles such as small
SUV’s and sedans use a
unibody (or monocoque)
construction.
Heavy-duty vehicles like trucks and busses still use
the idea of body-on-frame.
Regardless of the construction technique, steel is still
the predominant material used in automotive frames.
A Quick Comparison
Typical Ladder Frame
Monocoques
What it’s all About
Today, the new revolution in car design is the use of
new materials in the vehicle structure.
As fuel economy restrictions become tighter,
manufacturers must find new ways to meet them.
This has led them away from using so much steel in
the vehicles, and more and more are moving towards
aluminum.
The central theme of our project was to compare
these new lightweight aluminum cars to their steel
predecessors and see if anything is being sacrificed
and/or gained.
A Basic Comparison
Two common alloys used in car manufacturing:
For Aluminum: AA 5182
For Steel: AISI 1020
Steel
Al
Yield Strength
(MPa)
294.8
395
UTS (MPa)
394.7
420
Hardness
(HB500)
104
58
Data Courtesy efunda
http://www.efunda.com/materials/alloys/carbon_steels/show_carbon.cfm?ID=AISI_1020&prop=all&Page_Title=AISI%201020
http://www.efunda.com/materials/alloys/aluminum/show_aluminum.cfm?ID=AA_5182&show_prop=all&Page_Title=AA%205182
Properties
Density of Steel: 7.88 g/cm3
Density of Aluminum: 2.7 g/cm3
Aluminum is about 3 times lighter than steel per unit
volume, but can be made just as strong using certain
alloys/shapes/bonding methods.
Because of this, AL parts can be thicker, and thus
stronger, than their steel counterparts, all while
weighing less.
The Cost Issue
While Al may seem like a miracle metal for car
production, there is a reason not all cars are made
from Al... It costs a lot more than Steel.
The Move to Aluminum
The first production vehicle to move to an Al frame
was the Audi A8 in 1994.
This allowed Audi to make their full-size car lighter
than the competitions (BMW, Mercedes,Lexus...),
thus giving them the edge in performance & handling.
This comes at a price premium though, for instance
compared to a Lexus LS460 (Steel framed) which
costs around $65,000. The A8 starts at $75,000
Audi A8
Lexus LS460
An Increasing Trend
http://www2.prnewswire.com/mnr/duckerworldwide/37515/
Cars Utilizing Al Frames
Audi A8
Honda NSX
Jaguar XJ
Audi A2
Corvette Z06
Audi R8
Weight
The most obvious advantage to using aluminum in
place of steel in cars is aluminum weighs less.
Cars with Mostly Al
Space Frames
Safety
Not too many safety tests have been performed on Al
framed vehicles due to their usually higher price.
However, the Audi A2 is an inexpensive compact car
that has been tested, and received overall favorable
reviews compared to its steel bodies counterparts.
Some other advantages...
There are some manufacturing
methods that can only be done with
aluminum, such as extrusions.
These extrusions allows the Al
Space Frame to have about half the
amount of parts as a traditional steel
monocoque.
Because of all this, Al is already a
cheaper material to use for low
volume production cars (under
100,000 units a year or so).
A Few Other Facts...
Today, the average car contains about 200 pounds of
aluminum parts.
Aluminum space frames (like that from Audi), contain
fewer parts and fewer connection nodes, which helps
keep production costs lower.
In The Future
http://andrewbeard.wordpress.com/2009/05/11/technology-carbon-fiber-monocoque-chassis/
While Aluminum may be the wave of the future for
now, some exotic car companies are already looking
ahead to composite materials.
Take for example Porsche Carrera GT, which used a
completely Carbon-Fiber monocoque construction in
addition to Carbon-Fiber body panels.
Because of this, the curb weight of the car was only
3000 lbs., even with a 5.7L V-10 engine powering it.
Porsche Carrera GT
http://upload.wikimedia.org/wikipedia/commons/thumb/6/65/Porsche_Carrera_GT__Goodwood_Breakfast_Club_%28July_2008%29.jpg/800px-Porsche_Carrera_GT__Goodwood_Breakfast_Club_%28July_2008%29.jpg
References
Building an aluminum car
http://www.allbusiness.com/professional-scientific/scientific-research-development/443897-1.html
History of Automobile Body and Chassis
http://www.carbodydesign.com/articles/2005-04-13-chassis-history/2005-04-13-chassis-history.php
Automobile Bodies: Can Aluminum Be an Economical Alternative to Steel?
http://www.tms.org/pubs/journals/JOM/0108/Kelkar-0108.html
Different Types of Chassis
http://www.autozine.org/technical_school/chassis/tech_chassis2.htm
Aluminum Versus Steel
http://www.travistrailer.com/public/pag16.aspx