Automakers Turn to Simulation-Driven Design to Meet Efficiency Rules

Nov. 22, 2011
Intelligent simulation is a key technology in weight-management strategies for OEMs, and simulation-driven design is establishing processes that can help rapidly accelerate the industry toward the fuel economy and emissions goals down the road.

Manufacturers are recognizing that new rules relating to the ways automotive technology impacts our lives require new technologies to change the way we build vehicles.

In the United States, new and existing regulations requiring dramatic improvements in mileage for both cars and trucks already are creating another revolution in vehicle design, as OEMs attempt to make their products lighter, more fuel-efficient and less polluting. In Europe, legislation mandating reduced CO2 emissions by as much as 30% over the next few years is leading to similar design reconsiderations.

Designers are employing several strategies to attain new levels of light-weighting, which will translate into better mileage and lower levels of emissions.

One technique has been the introduction of multiple types of materials to substitute for conventional steel. Using a combination of metal alloys and lighter substances -- like aluminum and composites -- designers are making vehicle weight a primary factor in their work.

Traditionally, the industry has sought to balance cost and performance, with weight as an outcome of performance. Now, however, weight is being controlled and proactively engineered, elevated to equal status with cost and performance in balancing design considerations.

For example, engineers fabricating the BMW M3 bumper beam -- ordinarily a metallic structure -- have substituted steel for a glass-fiber-filled polymer and are achieving a 40% weight reduction. The Audi A8 spare-tire wheel well uses a similar material to achieve a 30% weight saving.

In addition, many designers are focusing on developing lighter body-in-white structures, because they estimate that shaving 1 kilogram of weight from this primary structure allows them to save an additional 1 kilogram in secondary mass on other components that can be built of more lightweight materials.

Even more significant for light-weighting, however, may be vehicles like the BMW i3, which not only employs an electric powertrain but also is constructed primarily from composites. It is planned as the first high-volume composite vehicle and is the type of technology envisioned and required by the future rules of the road.

Intelligent Simulation is a Key Technology

Whatever the strategy, designers and engineers will need to rely on sophisticated, intelligent technology to optimize the designs of the components, systems and vehicles they produce, ensuring they are designed with the least amount of material that enables maximum performance.

Without simulation tools, such optimization can be difficult. Composites, for example, add great flexibility to vehicle design, but this flexibility is accompanied by increased complexity.

To guide their efforts, designers are turning to intelligent software tools, such as OptiStruct, that can automatically recommend the most optimal design configuration.

Whereas computer simulation has long been used to validate designs at the end of the development process, designers and engineers increasingly are recognizing the value of introducing simulation to their processes at the very earliest ideation stage and then incorporating simulation in each of the succeeding stages. The auto industry is adopting this simulation-driven design process as a methodology for meeting the light-weighting requirements that confront their planning.

For example, using OptiStruct as part of a simulation-driven design process, a team at Altair ProductDesign developed the body-in-white for the SAIC Roewe 550. They screened every component of the vehicle for its optimization potential, and OptiStruct was applied to all those that could be effectively optimized.

Altair ProductDesign applied a variety of optimization methods -- including free-form optimization -- in which the designer indicates the forces on and space restraints for the product, and the software creates the optimal material layout for that space. In the earliest stages, concept optimization allows designers to look at global performance characteristics.

As the program progresses, the focus shifts to local performance and continuing to go after more mass reduction. Design of the Roewe 550 involved a massive deployment of optimization technology for all attributes, including crashworthiness, noise-vibration-harshness and durability.

The role of optimization tools will expand further as the auto industry evolves. With the smaller electric powertrains, for instance, designers gain more creative freedom to use free-form optimization to design new vehicle architectures. Optimization tools can provide invaluable guidance in developing these designs.

The adoption of simulation-driven design is rolling throughout the auto industry, as the design process is impacted by increased computing power, more software integration, and the predictability and intelligence that today's computer-aided engineering tools can offer.

Intelligent simulation is a key technology in weight-management strategies for OEMs, and simulation-driven design is establishing processes that can help rapidly accelerate the industry toward the fuel economy and emissions goals down the road.

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