Multibody Analysis of Lever-Spring Landing Gear with Elastomer Shock Absorbers: Modelling, Simulations and Drop Tests

This study investigates the ground reaction force of lever-spring landing gear (LSLG) equipped with compressible elastomer shock absorbers (ESA) during the landing process. First, a numerical dynamic model of the LSLG was developed in MATLAB/Simulink, revealing that runway roughness exerts a negligible influence on the ground reaction force during landing. The load characteristics established fundamental references for subsequent FEA-based structural design. Furthermore, an FEA model integrating the LSLG and the aircraft was developed with parameters calibrated for elastic units. The multibody dynamics simulation (MBDS) quantified the vertical ground reaction force and the structural stresses of LSLG, demonstrating two critical relationships: (1) the overload coefficient correlated with the sinking velocity yet exhibits no correlation with aircraft mass and (2) the peak of oscillating force attenuated faster with heavier landing weight at higher sinking velocities. A nonlinear multi-variables function was fitted to predict the maximum vertical ground reaction force. Subsequently, experimental validation via a landing gear drop test (LGDT) showed a maximum error of 8.39% between the results of the LGDT and the MBDS, confirming the accuracy of simulation and the fitting surface function for force prediction. The study further validates the feasibility and reliability of using the MBDS to model and study the LSLG with ESAs.