Analysis of transient phenomena in automotive vehicle suspension dampers

An automotive damper is a mature technology in the industry. From an engineering standpoint, the device design is a compromise between handling characteristics of a car, passenger comfort and safety, NVH and durability. Recently, new automotive trends in vehicle chassis design have generated research and engineering efforts. The engine and powertrain vibration reduction, the entry of hybrid/electric vehicles have caused all vibration sources due to vehicle chassis operation recognizable by both driver and passengers. Moreover, due to the increasing structural stiffness requirements imposed by vehicle OEMs (Original Vehicle Manufacturer) the energy dissipation efficiency of the damper has become a research and engineering challenge. It is, therefore, vital to propose means for eliminating or reducing their influence through changes that will result in vibration level reduction and techniques methods, metrics for evaluating them. In the dampers any disturbances in force generation translate into the device's internal pressure fluctuations, and then piston rod vibrations transmitted to the body of the vehicle. It has been identified the pressure fluctuations are due to the valves' inadequate performance. The dynamic effect known as rattling is detrimental to the passenger's comfort. The phenomena have unique noise/vibration characteristics which can be related to the valves' operation within the frequency range usually from 200 to 600 Hz. In the paper the authors investigate the opportunities for identifying the transient phenomena characteristics using a time and frequency domain signal processing technique – Short Time Fourier Transform. They examine a number of damper configurations, test them, and then apply the technique for the purpose of analysing related symptoms. Finally, they draw conclusions.