Chassis is responsible of the vehicle basic performances of safety, comfort, driveability but plays an important role also in determining the vehicle’s weight and cost.

Mission of this activity is to show the weight reduction potential of a structural chassis component using the best mix of materials, forming and joining technologies. The goal is to obtain, at affordable cost, the same performances of a conventional steel sample (in term of static and dynamic stiffness, crash behaviour) archiving at the same time a 35% of weight reduction.

The chassis sub-component selected for this study is the front sub frame of a D segment reference car. This is in fact a challenging test case due to the several constraints and mission that the components has to deal with: 

• suspension arms, engine tie rods, antiroll bar, steering rack are fixed on it;
• the sub frame has to bear road loads;
• sub frame must be stiff enough to avoid vibrations and optimize handling behaviour;
• during front crash the sub frame deformation helps to absorb kinetic energy.

The HYBRID subframe achieves the target 35% weight saving with same packaging and performances of conventional reference solution. This result is obtained through a complete redesign of the original project. Materials, shapes and technologies are chosen with the aim to put “the best one at the right place”.

For instance, longitudinal extruded rails are chosen to maximize energy absorption during crash, cast aluminium parts are used where tight tolerances and high stiffness are required, stamped steel is placed where high Young Modulus and elongation are necessary.