With the widespread use of composite materials and the increasing demand for weight reduction in modern aircraft, the stiffness of the fuselage has gradually decreased, leading to more frequent occurrences of pendulum motions. Traditionally, pendulum test rigs often overlook the elasticity of the fuselage, which can affect the accuracy of the pendulum test results. This study, based on fuselage dynamic characteristic simulation, simulation criteria, and two-degree-of-freedom vibration theory, decouples the bending and torsional degrees of freedom to design a combined bending–torsion fuselage simulator. Using finite element analysis in HyperMesh, the fuselage stiffness and modal information were obtained and incorporated into the simulator for parameter calculation. Both the mass and spring parameters meet the design requirements, and the model’s accuracy was validated through modal testing. Finally, a dynamic equation system for the landing gear’s pendulum motion, considering the fuselage’s dynamic characteristics, was established. The impact of fuselage elasticity on the stability of the pendulum motion was analyzed, and the results indicate that fuselage elasticity lowers the pendulum frequency of the aircraft’s landing gear. When the system’s pendulum frequency approaches the fuselage’s natural mode, pendulum phenomena are more likely to occur. Therefore, the impact of fuselage elasticity should not be neglected when studying the pendulum stability of modern aircraft landing gears.
Hou et al. (Fri,) studied this question.