Abstract
To investigate the influence of nonlinear transmission characteristics of a semi-levered nose landing gear mechanism on landing impact responses, a nonlinear dynamic model calibrated using quasi-static load–stroke tests is established. The coupling relationship between wheel-axle motion and shock-strut stroke is derived through kinematic analysis of the mechanism, while the effects of the oleo-pneumatic shock strut, nonlinear tire characteristics, and wheel spin-up are incorporated into the model. Cross-validation is performed using an ADAMS model. The analytical model agrees well with the ADAMS model in terms of the major response trends and peak-value predictions, demonstrating that the proposed model can effectively capture the landing impact characteristics of this type of landing gear. Parametric analysis indicates that the diameter of the main metering orifice is a key parameter governing the trade-off between impact load and shock-strut stroke. At Dn = 6.0 mm, the system exhibits a favorable overall response, and a candidate design range of 5.6−6.4 mm is further identified. The results provide a theoretical basis for landing-response prediction and shock-absorption parameter matching of semi-levered nose landing gear.