Lightweighting

When applied to an optimized automotive body structure, aluminum can provide a weight savings of up to 50 percent compared to an equivalent steel structure. Aluminum body structure stiffness and crashworthiness are equal or superior to steel.

These results can be achieved, even though the stiffness modulus of aluminum is only one-third that of steel, because aluminum has only one-third the density of steel and a higher strength-to-weight ratio. By using appropriate increases in aluminum thickness and section size coupled with efficient joining, body structure strength and stiffness targets can be met at metal thicknesses about 1.5 times those of steel and still result in a 50 percent weight reduction.

For body panels such as hoods, decklids and fenders, aluminum can yield even larger weight savings. And alloys 6111 and X6022, which strengthen significantly during E-coat paint baking, provide dent resistance equal or superior to steel.

The chart below for the Ford Taurus/Sable-based aluminum-intensive vehicle (AIV) illustrates what can be achieved in such a vehicle where the unibody structure is weld bonded for efficient joining. The structure was not redesigned, yet a weight savings of 46 percent was achieved.

* Unglazed body structure
Note also the increased torsional rigidity

* Unglazed body structure
Note also the increased torsional rigidity

	Steel	Aluminum	Weight Saved	% Chg
Body structure (lbs.)	596	320	276	-46
Hood, deck & fenders (lbs.)	90	38	52	-58
Front and rear doors (lbs.)	132	79	53	-40
Total body-in-white (lbs.)	818	437	381	-47
Torsional rigidity (ft. lb./deg)*	7.4	11.0	—	+49
Total vehicle (lbs.)	3245	2894	381	-11.6

Primary weight savings also enable many of the other vehicle systems to be downsized, such as the engine, transmission, brakes, suspension, wheels, etc. The chart above shows how hypothetical secondary weight savings in a mid-sized sedan could lead to a total weight reduction of over 700 lbs..

These weights can be further reduced by using aluminum for manufacture of the components. Both Ford and Chrysler demonstrated this in their Synthesis 2010 and Neon Lite concept vehicles with weight savings of 900 lbs and 680 lbs respectively.