SATURN'S SPACE-FRAME TECHNOLOGY IMPROVES VUE'S HANDLING, SAFETY

The Saturn VUE represents the next evolution of Saturn's space-frame technology that provides important benefits to customers. The structural composition plays a big part in VUE's responsive handling, contributes to a quiet interior, helps absorb and dissipate the impact of a crash, and reduces weight in order to improve fuel economy.

"VUE's welded-steel space frame allows us to structure the vehicle for optimum strength with minimum weight," said Jim Ulrich, Saturn vice president of engineering. "The VUE's structure furnishes the stiffness needed for outstanding ride and handling characteristics. High rigidity also is necessary for a smooth, quiet ride free of squeaks, rattles and wind noise. In addition, the space-frame structure has inherent safety advantages, providing a protective steel cage to help maintain the integrity of the passenger compartment during a crash."

Backbone of every Saturn
The VUE benefits from Saturn's many years of experience with space frames, which are the backbone of current S-Series and L-Series vehicles. Constructed almost entirely from high-strength steel, the VUE's space frame incorporates full-length frame rails and a rugged steel safety cage in a single, welded unit. The space-frame approach, along with the use of polymer panels for fenders, doors, quarter panels and fascias, maximizes stiffness while minimizing mass.

Conventional vehicles have inner and outer skins of metal, with the outer skin defined by styling requirements. As a result, the inner skins must carry most of the structural loads. This is accomplished by adding reinforcements where needed.

An advantage to Saturn's approach is that engineers don't need to be concerned about styled surfaces, because polymer panels fulfill that role. This means they can shape the inner steel skin to best meet structural requirements.

Single-piece side frame
VUE's single-piece side frame runs from the A pillar to the rearmost part of the vehicle. In addition to contributing a highly efficient continuous load path, the single-piece design yields consistent door fits to minimize wind noise and water leaks, while enabling a high quality fit and finish. The area around the front hinge and A pillar has higher-yield-strength steel and increased thickness to resist roof crush, while the rocker uses higher-strength steel and a galvanized coating for corrosion protection.

Higher thickness and yield strengths are used in the forward portion of the inner door panels. The panels also are bolstered with X-shaped reinforcement beams to resist intrusion during a side impact.

"The VUE's structure is designed to crush progressively at both the front and rear in order to absorb collision energy while maintaining passenger compartment integrity," Ulrich said. "As part of this design, the main underbody rails run continuously from front to rear and help to absorb front and rear collision forces."

Multiple purposes
Many structural elements serve multiple purposes. A welded-steel beam inside the instrument panel supports both the instrument panel and steering column, serves as an air duct for the HVAC system, and contributes to body structural rigidity and side-impact strength. Cradle assemblies at the front and rear of the vehicle that carry driveline, steering and suspension hardware also serve key structural roles, especially in absorbing collision forces.

The front bumper beam, an add-on item in most vehicles, is welded on, contributing to front-end stiffness and eliminating the need for an extra crossmember. Front suspension towers are solidly tied to the dash and ventilation plenum area of the vehicle as another aid to rigidity. To further add stiffness and durability, weld-through structural adhesive is applied in certain areas of the structure.

Low step-over rockers facilitate easy entry and exit, without the need to climb up and over a tall sill. An inner rocker brace helps absorb energy during a rear-offset collision.

A wrap-around upper tie bar at the front of the engine compartment helps assure a high level of accuracy in fender, headlamp and fascia attachments.

High-strength steel is used for 90 percent of the space-frame structure, including every major structural member. This saves weight and improves fuel economy. In addition, all underbody, engine compartment and roof panel components exposed to the environment are made of galvanized steel to protect against corrosion.

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