On The Problem Of Dependence Of Damper Force On The Concentration Of Free Air In Working Liquid

In-process of damping of vibrations with great velocities (greater then 2 m/s) the concentration of the free air in working liquid of the two-jacket hydraulic damper increases. This phenomenon is allowed by the free surface of the liquid in the accumulator of the damper and invoked by the changes of equilibrium conditions between the quantity of air evolved from liquid and the quantity of air dissolved in oil in dynamic state for greater damping velocities. In the paper two unfavourable effects of this phenomenon are analyzed: delay on the working damper characteristics, which leads to the considerable degradation of damper force, and decrease of damper valve resistance to the self-excited oscillations. These vibrations can arise in steady parts of both damper expansion and rebound phases where all transient phenomena have gone off long ago and working valves are fully open. The zones of self-excited vibrations coincide with regions of linear asymptotic instability of the system, i.e. with the areas where the real part (natural damping) of at least one of the damper eigenvalues achieves positive value.