Aircraft landing gear system with magnetorheological shock strut: Performance evaluation via drop test

This work presents a magnetorheological (MR) damper applicable to the landing gear system in the aircraft. The proposed MR landing gear (MRLG) is modeled as a two degrees of freedom (2-DOF) system for the drop performance evaluation. A mathematical model of the governing equations is then formulated considering a flow path whose pressure depends on the major and minor losses. The flow path of MR fluid is composed of annular orifice and bypass as the required damping force for compression and extension is much different, and relief valve operates in conformity with the motion direction of the piston rod. An entry region is added to guarantee precise controllability of the field-dependent damping force. In addition, the magnetic intensity and total loss coefficient are estimated using magnetic analysis and computational fluid dynamics tools, respectively. It is demonstrated from the drop test based on the Federal Aviation Regulation (FAR) Part 23 that the shock struct efficiency (SSE) of the proposed MRLG can be increased from 42% at zero current to 84% at 1 A, and the agreement between simulation and experimental results is excellent showing similar pneumatic force, strut force, and jerk behavior which validates the accuracy of the proposed model.