Brake pulsation is a low frequency vibration phenomenon in brake judder. In this study, a simulation approach has been developed to understand the physics behind brake pulsation employing a full vehicle dynamics CAE model. The full vehicle dynamic model was further studied to understand the impact of suspension tuning variation to brake pulsation performance.
Brake torque variation (BTV) due to brake thickness variation from uneven rotor wear was represented mathematically in a sinusoidal form. The wheel assembly vibration from the brake torque variation is transmitted to driver interface points such as the seat track and the steering wheel. The steering wheel lateral acceleration at the 12 o’clock position, driver seat acceleration, and spindle fore-aft acceleration were reviewed to explore the physics of brake pulsation. It was found that the phase angle between the left and right brake torque generated a huge variation in brake pulsation performance.
Multiple analyses have been run to understand the relationship between the brake pulsation performance and suspension tuning. The suspension tuning parameters incorporated in the study were suspension bushing stiffness, bushing damping for a potential hydro-bushing implementation, the magnitude of the pulsation torque, unsprung mass, and spindle length.
Simulation results have demonstrated the physics behind the brake pulsation reasonably well. This study would enable engineers to find a good compromise of suspension tuning to improve brake pulsation in vehicle dynamics performance.