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

Abstract

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.

Landing Impact Load Analysis and Validation of a Civil Aircraft Nose Landing Gear

“…This figure shows that both the loads at the WA center and GC point and both the loads in the vertical and longitudinal directions were all in good agreement between the simulation and test, validating both the accuracy and comprehensiveness of the work previously performed. Compared with other studies on the drop test [4,8,17,32,33], the longitudinal tire loads are basically similar in shape, as are the vertical history loads, but the longitudinal loads of the wheel axle, as described before, were not obtained in previous tests. This test result proves that a significant load difference between the WA and GC exists and could motivate other researchers to conduct WA load research.…”

“…The minimum absorption efficiency of 65.9% meets the requirement of 65%. Compared with other studies published recently [4,8,17,33], in which the efficiencies ranged from 60% to 80%, the design of the nose landing gear described herein is adequate, and the properly designed oleo-pneumatic shock absorber has been proven to have stable performance.…”

“…This shows that the shock absorber efficiency of the gear can meet the minimum shock absorber efficiency requirement (greater than 65%). Compared to the other cases [4,8,17,33], the curve shapes and the absorber efficiencies are basically similar. However, if the vertical loads before 250 mm can be optimized from 100 kN to about 150 kN by redesigning the damping parameter, the absorber efficiencies may be better.…”

“…Numerous studies have been conducted on the fundamental components of the system, including the air spring force, oil damping, bearing friction, tire deflection, wheel rotation, tire friction, structural arrangement, and structural flexibility [5][6][7][8][9][10][11][12][13]. Some studies have even looked at the impact from the aircraft level, like airframe flexibility, aerodynamics, and the controller systems effect [14][15][16][17][18]. Nowadays, theoretical modeling and simulation analyses are still crucial areas [19][20][21].…”

Design, structure analysis and shock control of aircraft landing gear system with MR damper

“…In the above, H is the Heaviside step function; k t and κ refer to the tire stiffness coefficient and index governing the tiredeflection process, respectively. The tire stiffness coefficient and index, yield stress, and optimal parameters for MRAMLG were determined in previous research [17]. In the previous study that optimized the MR valve using the Karush-Kuhn-Tucker conditions, the orifice gap was set as a decisive variable that minimizes uncontrolled SSE under the constraints of the optimization problem, where the constraints are as follows:…”