Automotive dampers are essential vehicle components regarding vehicle dynamics by
keeping the road contact and reducing wheel load fluctuations. So damper
degradation could not only significantly influence driving comfort but also the
dynamics and therefore driving safety. The aim of this study is to expand
knowledge about the behavior of passive automotive twin-tube dampers degraded by
loss of oil and pressure. This serves to improve the understanding of inner
processes of the damper and modeling the behavior of degraded dampers. To
analyze the damper behavior, an intact damper has been modified and validated to
allow adjusting the oil and pressure level. Using a dynamic hydraulic damper
test rig a preconditioning routine for degraded dampers is developed. With this
routine, a wide measurement program at various amplitudes, frequencies,
oscillations, and damper configurations is carried out and the obtained results
are discussed. The conducted measurement program did not cover small amplitudes
(<8.4 mm) and high frequencies (>19 Hz).
The results show that the loss of oil or pressure leads to complex dependencies
on all varied parameters such as amplitude, frequency, number of oscillations,
and waiting time between two measurements. While the absence of pressure only
leads to small performance reductions, especially the loss of oil leads to
significant deterioration of the damper performance. Already at a level of 90%
of the original oil volume, the examined damper loses up to 30% of its
performance under disadvantageous operating conditions. Furthermore, the loss of
oil can make a damper almost useless when 40% of the oil is still present.