Modeling and Simulation of a Vehicle Suspension with Variable Damping and Elastic Properties versus the Excitation Frequency

Usual vehicle suspensions employ hydro-pneumatic absorbers (e.g., oil, colloidal and air dampers) mounted in parallel with compression helical springs. Although the damping coefficient of the vehicle suspension is changing versus the excitation frequency, conventional design method is based on simplified models that assume for constant damping and elastic properties. In this work, three types of suspensions were considered and modeled as follows: oil damper mounted in parallel with a compression helical spring, for which a Kelvin-Voigt model, consisted of a dashpot and an elastic element connected in parallel is considered, colloidal damper without attached compression helical spring, for which a Maxwell model, consisted of a dashpot and an elastic element connected in series is considered, and colloidal damper mounted in parallel with a compression helical spring, for which a standard linear model, consisted of a Maxwell unit connected in parallel with an elastic element is considered. Firstly, the vibration transmissibility from the rough road to the vehicle´s body for all these suspensions was determined under the constraint that damping varies versus the excitation frequency. Then, the optimal damping and stiffness ratios were decided in order to minimize the transmissibility of vibration from the rough pavement to the vehicle´s body. Such results are useful to improve the vehicle´s ride-comfort.