Investigation of magnetorheological shock absorber used in semi-active suspension

Abstract

The automotive industry is rapidly moving towards autonomous vehicles. In this case, the answers of the vehicles can be change in different scenarios. At this point, the suspension system must be semi-active or fully active. Magnetorheological shock absorbers can be used in semi-active suspension systems. In this study, studies were carried out on the examination and testing of magnetorheological shock absorbers. These systems can change the stiffness of the shock absorber with the effect of magnetic field depending on the data coming from the road and the condition of the vehicle. It does this by changing the viscosity with the nano powders affected by the magnetic field. Ferromagnetic nanoparticle additives are used in the shock absorber. However, one of the biggest risks in these shock absorbers is the precipitation of nano powders in the oil. If this happens, it starts to fail to fulfill its shock absorber feature. To prevent this, oil density and nano powder density should be close. In this study, low density polystyrene coated with magnetic material and these particles was added to the oil in the shock absorber. As a result, particles with a density of 0.877 gr/cm3 were obtained and oil with a density of 0.971 gr/cm3. As a result of the observation, no significant precipitation was observed in the liquid formed. A prototype MR damper was produced using this mixture. In the next step, the effects of the electromagnetic field on the shock absorber were investigated and the shock absorber is controlled by electromagnetic field. As a result, the piston velocities of the damper in response to the force were measured under 3 different forces, without magnetic particles and at different current values after the magnetic particle was added. Damper hardening with current was observed.