Optimization of a Semi-Active Shock Absorber for Aircraft Landing Gear

Abstract

We propose an optimization method for a semi-active shock absorber for use in aircraft landing gear, in order to handle variations in the maximum vertical acceleration of an aircraft during landing caused by the variation of the aircraft mass due to the variations in the number of passengers, and the amounts of cargo and fuel. In this optimization, the maximum vertical acceleration of an aircraft is set as an objective function to be minimized. Design variables searched in the first step of this optimization are discrete orifice areas formed by the outer surface of a hollow metering pin and a hole in the semi-active shock absorber. The design variable searched in the second step is a compensating orifice area which is controlled based on the mass variation. Using the optimum target orifice area obtained in the second step, we optimally determine a practical orifice area that is controlled by a stepping motor. The optimizations for a passive shock absorber and for semi-active shock absorbers with target and practical orifice areas indicate that the semi-active shock absorbers can handle aircraft mass variation much better than the optimum passive shock absorber. Furthermore, the robustness of the optimum practical orifice area controlled by a stepping motor is shown via simulation.