QFR18: Anti-roll bar design

Queen’s Formula Racing’s performance in Formula Student 2017 was one of its strongest in recent years. Topping the timesheet in the acceleration run was a highlight but the team was let down by disappointing times in the skid-pad event. This marked a clear development path for QFR18, to improve the car’s handling.

In a bid to improve the car’s handling, a final-year project was devoted to the design of a new anti-roll bar system. Mechanical Engineering student, Andrew Hawthorne, is responsible for the new design.

Anti-roll systems connect the movement of one wheel to the other. When cornering, roll causes the outside spring to compress and the inside spring to extend. An anti-roll system uses the torque along the anti-roll bar, created by load transfer, to provide resistance to roll. This reduces roll, helping to control camber change and maximising tyre traction.

“The newly designed anti-roll system is fully adjustable,” explained Andrew. “Allowing the vehicle’s load transfer and tyre loads to be altered whilst controlling body roll.

“This allows fine-tuning of the car’s dynamics, permitting optimal vehicle handling.

“Feedback from QFR17 suggested that its performance suffered because of understeer.

“After further testing this year, we believe it was due in part to an overly stiff anti-roll bar.”

Following calculations, an appropriate anti-roll bar stiffness was chosen and in co-operation with the suspension team, a greater understanding of the car’s total load transfer characteristics was gained.

To reduce anti-roll bar stiffness, a hollow tube was integrated into the system as opposed to the solid bar used last year. Not only will this improve the car’s handling, but it has also helped reduce the system’s overall mass by 600 g.

Another component which was redesigned to reduce mass was the anti-roll bar moment arms. This component translates the vertical motion of the drop-link to anti-roll bar twisting. Andrew used FEA to design a lighter moment arm and tested the new design to ensure it meets its strength requirements.

Moment arm QFR18

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