Brake-Dive Sensitivity Analysis Using a Five-Degree-of-Freedom Lumped-Mass Model and Design of Experiments

The sensitivity of the brake dive of a sport utility vehicle (SUV) was analyzed using a five-degree-of-freedom (5-DoF) lumped-mass model and design of experiments (DoE). A program was developed and validated using Visual Basic for Applications (VBA). The analysis parameters used actual kinematics and compliance (K&C) data without linear assumptions, enabling detailed numerical and systematic descriptions of previously unorganized knowledge obtained from the experiences of tuning engineers. The initial shock and residual ripple of the nose-dive angle were defined as DoE performance metrics, and the required suspension parameters and shock absorber piston speeds were identified. The initial shock was greatly influenced by the rear and front spring forces, followed by the rear rebound damping, rear anti-lift force, and front anti-dive force. Further, the residual ripple was highly sensitive to the front and rear rebound damping forces. The initial shock can be improved to some extent by applying only shock absorber tuning to effectively reduce the residual ripple.