Kinematic reliability evaluation of landing gear door lock mechanism with non-uniform joint clearances

This study investigates the kinematic reliability of a landing gear door locking mechanism, incorporating the influence of non-uniform clearances within joint interfaces. These clearances, primarily resulting from operational wear, significantly affect the accuracy of the mechanism. Existing research has largely focused on planar mechanisms under the assumption of uniform clearances, which often deviates from actual operational conditions. In this work, non-uniform clearances are parameterized using B-spline curves. This study establishes a positional deviation model accounting for irregular joint gaps, input parameter variations, and geometric imprecisions within the mechanical linkages. Through analytical derivation, the expected value and variance-covariance matrix of positional error distribution are obtained, while the probability density function (PDF) is calculated utilizing the central limit theorem framework. Kinematic reliability within the workspace is subsequently assessed through direct integration of the PDF. This approach is broadly applicable to mechanisms with irregular joint clearances caused by wear and is validated through Monte Carlo simulations, confirming its accuracy and effectiveness.