Anti Roll Bar Design
Please enjoy the 2-minute summary gallery below, or scroll further to explore my work in greater detail
As is readily apparent on this website, the majority of my work pertains to vehicle dynamics modeling and simulation, as well as kinematic design. My skills are not limited to computer coding and dynamic systems, however! One of my other design projects for the 2020 Clemson Formula SAE car was the anti-roll system, and on this page I'd like to walk you through the major steps in the design and development process.
Rendering of the Tiger22 Front Suspension Assembly, including anti roll bars.
Early on in the full vehicle design exploration, the team had decided to pursue a suspension concept with decoupled pitch and roll modes. Typical decoupled suspensions employ a bi-directional spring and damper element, which can introduce cost and complexity to develop. Other teams have worked around this by implementing two roll units, one which actuates in either roll direction, but this is a heavier and larger solution. We decided to use an anti-roll bar (ARB) for the relative simplicity, packaging freedom, and cost to develop. As a bonus, shifting the ARB pickup points to the pitch rockers enabled us to minimize torsion loads across the actuation axes, minimizing weight and compliance.
Design table summarizing the primary considerations behind each concept
Example of a decoupled suspension, with bi-directional roll element, on the Mercedes-AMG Project One.
Source: Topspeed.com, 2017, www.topspeed.com/cars/mercedes/2020-mercedes-amg-project-one-ar167883.html.
Moving forward, I created a list of constraints and criteria to guide the project and design direction. The static roll stiffness targets were calculated from target roll gradient and roll center locations which had already been finalized by that point.
One of the most important functions of anti roll bars are to serve as adjustment tools to fine-tune the cornering balance of the vehicle. Because of this, the criteria to "Maximize adjustment range and resolution" was one of the most important considerations throughout the design process. Before moving forward, it was important to quantify what adequate adjust-ability looked like. Neglecting kinematics, I explored the effect of the lateral load transfer distribution on the steady state handling balance of our vehicle. These results were supplemented by steady state directional control testing data (using SAE J266 test procedure) characterizing multiple setups on an older vehicle. Based on driver feedback of these setups, a target understeer gradient of 0.45 deg/g was selected, with a threshold of 1.5 deg/g before driver complaints became significant.