The need to build lighter cars is being driven, in large part, by the United States, which will require all new cars and light trucks sold in the country to meet 40 percent higher fuel efficiency standards by 2020.

"Honda, like all automakers right now, is looking to lightweight our vehicle without compromising safety standards," says Duane Detwiler, Manager and Chief Engineer, Vehicle Structure Research—Reliability at Honda R&D Americas, based in Raymond, Ohio.

More than $600,000 was awarded through the Automotive Partnership Canada (APC) initiative to support the research, which builds on an earlier NSERC-supported project that successfully used tailored hot stamping to develop a key part in the midsection of the car, called a B pillar, which protects passengers in a side impact.

Currently, auto parts makers heat up steel to about 950 degrees Celsius until it is soft enough to form, and then quench it in water for rapid cooling to guarantee uniformed strength throughout. This high-strength steel is primarily used in the safety cage—the vehicle frame that surrounds the passenger compartment.

The University of Waterloo has built a prototype die that is able to heat certain sections of a part while leaving other sections cold. By changing the cooling rate, it becomes possible to achieve different levels of strength within a single part. The rapidly cooled regions display ultra-high strength, while the slower cooling rates impart lower strength, but enhanced energy absorption.

"We're achieving safety in the cage today using a weaker material of greater thickness," explains Detwiler. "With this new process, we could use stronger steel that's thinner, with one part serving multiple purposes instead of having multiple parts with different thickness and different materials. You have the potential to reduce both the cost of future vehicles while keeping the same high level of safety."

Tailored hot stamping is being used by some automakers, but the design is done on a trial and error basis which increases design costs. This APC project will develop computer models that simulate and predict how these tailored materials will perform in the event of a crash.

"We will be simulating the whole experiment from the manufacturing right through to service performance and crash testing," says project leader Michael Worswick, at the University of Waterloo's Department of Mechanical and Mechatronics Engineering. "When we're done, we will have a complete set of material behaviour, and know how to do the tailoring and how to model those tailored parts in a full car crash which companies like Honda or Promatek could then incorporate into their product design. That's our ultimate goal."