Automobile Materials SRJC - ENGR 45 Semester Project (Fall ’09) Brian Goff Mario Grasso Oscar Briceno

Courtesy Car Body Design 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 Audi A8 Lexus LS460 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