Analysis of nonlinear vibration transmission through a vehicle suspension damper at low audio frequencies

Active control is an attractive solution to the problem of structure-borne interior road noise in cars. However, nonlinear suspension dynamics could limit the cancellation that can be achieved with a linear feedforward road noise control system. The hydraulic dampers in a vehicle suspension have previously been found to be a source of nonlinear vibration transmission at low audio frequencies. This paper presents experimental measurements and modelling of the front and rear suspension dampers in a test vehicle aimed at understanding the physical processes causing their nonlinear dynamics. Experiments are shown that highlight the different nonlinear effects present in the dampers, including friction and the mechanics of the piston valves. A suitable model was then selected from the literature, fitted to the measurements and validated. Analysis of the models revealed that, in the front damper, both friction and the valve mechanics contribute significantly to the damper’s nonlinear dynamics between 50–300 Hz. Friction in the rear damper is much less significant, meaning that its nonlinear dynamics are almost entirely caused by the piston valves. Although the front damper’s friction behaviour proved challenging to model, the effect of the piston valves was captured very accurately in both damper models. •Experiments and modelling identify important nonlinear processes in two suspension dampers.•Nonlinear vibration transmission in the front damper is due to friction and the valves.•Friction in the rear suspension damper is less significant than in the front.•Nonlinear vibration transmission in the rear damper almost entirely due to the valves.