Singularity Analysis and Optimization Design for Landing Gear Locking Performance Considering Ground Loads

The locking mechanism assumes the responsibility of locking the landing gear in the extended position, which is the key to ensure that the landing gear is stable to withstand the landing load of the aircraft. However, the reciprocating change in the direction of the spin-up and spring-back ground loads can cause vibrations in the locking mechanism, potentially leading to unintended unlocking during the landing phase. Designing mechanisms with enhanced locking performance is challenging due to a lack of analysis techniques and design indexes. Thus, this paper presents a technique using numerical continuation and singularity theory to analyze and optimize locking performance, focusing on the over-center lock mechanism. First, the impact of the landing gear on the locking performance at various singular positions is studied. After discussing the motion law of the configuration with varying numbers of singular points under ground load action, the critical unlocking condition is discovered. Second, the inclination angle between the locking point and the singular point is defined as the locking performance index based on the principle of virtual displacement. The influence of structural parameters on the singular point position and locking performance is analyzed, and the evolution mechanism of the number of singular points is expounded. Finally, a comprehensive optimization model with locking performance as the optimization objective is established. Results show that combining singularity analysis with numerical continuation effectively captures performance trends with structural parameters, significantly improving the landing gear’s critical unlocking load by 108% and reducing the locking mechanism’s oscillation angle by 87.5%.