The United States Automotive Materials Partnership LLC (USAMP) has successfully built a new magnesium-intensive vehicle front-end body structure. The milestone experiment, a part of the group’s Magnesium Front-End Research and Development (MFERD) Project, was carried out to establish the practicality of building such a structure in order to build lighter, yet equally safe, production cars.
Phase I of the project indicated it is possible to achieve a 45 percent final net weight reduction in a magnesium-intensive front-end unibody structure and a 24 percent weight savings in a body-on-frame architecture through increased use of magnesium, when compared to baseline designs using conventional materials.
In addition to the reduction in weight, the part count was reduced by 59 percent through the integration of die casting and addition of aluminum extrusions, while meeting all specifications for vehicle stiffness and fatigue and with a crashworthiness equivalent of the baseline models based on simulations.
Two front-end architectures were selected by the project team; a rear-wheel-drive (RWD) unibody represented by the Cadillac CTS passenger car and a body-on-frame (BOF) represented by the Ford F-150 pickup truck. The OEMs provided the baseline steel data, vehicle design and performance targets for the USAMP team for hypothetical design and technical cost modeling of the magnesium front-end structures.
As part of Phase II of MFERD, the USAMP project team then designed, fabricated parts, assembled, surface finished and completed testing of more than 200 demonstration structures, representing major components in the unibody front end. Half of these magnesium structures were built using friction stir linear welding (FSLW) and the remaining structures were built utilizing a laser-assisted, self-piercing rivet (LSPR) process.
The first phase of the project ran from 2007 to 2009 and developed key enabling technologies in magnesium extrusion, sheet, high-integrity body casting, joining and assembly. During this pahse, a significant knowledge base was also established in magnesium corrosion protection, crashworthiness, fatigue and durability, and noise, vibration and harshness (NVH).
“Consistently improving vehicle fuel economy is important to everyone,” said Steve Zimmer, executive director at United States Council for Automotive Research (USCAR). “Vehicle lightweighting is an essential part of that effort, and USAMP is a key industry player in needed research and development.”
USAMP is a team within the United States Council for Automotive Research (USCAR), a cooperative research effort formed by GM, Ford and Chrysler.
by Collision Week: www.collisionweek.com/cw/news/2012/1129-rese.asp