| Steel
vs. Aluminum:
Crashworthiness
Current generation (in-production) front rail profile made from HSLA GR350 Steel compared to an aluminum extruded front rail profile from the a 2003 Honda Insight. Corresponding optimized hydroformed steel profiles proposed are shown on the left, which will have nearly identical performance in terms of crash energy management at nearly identical weight.
Today,
more than ever, safety sells cars. For car buyers it is a key element of
their purchasing decision. It's essential that consumers obtain reliable
and accurate comparative information regarding the safety performance of
individual car models.
The same crash
standards must be met by steel intensive and aluminum intensive
vehicles. Steel offers the best solution for:
- Maximum
energy absorption at mixed failure modes
- Energy absorption
in bending and axial collapse
- Positive
strain rate sensitivity
Based
on this U.S. Steel Product Technologies undertook a study to compare the
crush performance of the current Honda Insight front aluminum extruded
rail to an advanced high strength steel alternative, based on the
identical design space and test conditions.
Both rail designs tested utilize a hexagon profile at 3.5” in
diameter. However the
aluminum extrusion possesses a six-sided web structure in the interior,
while the TRIP 780 1.3 mm steel version was a hydroformed design produced
from a round tube into a hexagon profile.
Weight wise, there is a 10% differential.
Both
numerical and experimental studies were carried out at U.S. Steel to
compare the performance between the 1.3 mm TRIP 780 hexagon profile to the
Honda Insight aluminum extrusion profile.
As shown in the figures bellow, the TRIP 780 hexagon profile proved
almost identical performance to that of the 6XXX-T5 aluminum extrusion in
terms of crash energy performance. Again,
both parts are nearly identical in weight.
This
example exhibits the potential for the new steel grades being developed at
United States Steel for similar weight savings at a much lower cost than
aluminum use.
(click
for larger picture)
Example
of Real Life Frontal Crash Testing
(440 KB)
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