Reliability analysis of aircraft landing gear retraction and extension mechanism based on coupled dual-extreme value response surface method

Abstract

The landing gear system is one of the critical subsystems of an aircraft, directly affecting the safety of takeoff and landing. The landing gear retraction and extension mechanism (LGREM) exhibits strong nonlinearity, with complex coupling interactions among its parts. Using multi-rigid-body kinematics and dynamics to calculate stresses and strains of the LGREM would be highly challenging. This paper proposes a coupled dual-extreme value response surface method (CDEVRSM) that considers parameter coupling between parts. By taking the dual- extreme values obtained from finite element (FE) transient structural simulations as output responses, and using overload coefficient, material density, and gravitational acceleration as random variables, a response surface function (RSF) is constructed for strength reliability analysis of the LGREM. Employing the Monte Carlo algorithm with 1,000,000 large-scale sampling, the reliability of the LGREM is calculated to be 99.9844 % by statistical calculation. Its relative error was reduced by approximately 61 % compared with the extreme value response surface method. Moreover, compared to approximately 1000 hours required by FE methods, the CDEVRSM reduces computation time to approximately 10 hours, greatly improving computational efficiency. The sensitivity of three random input variables to the reliability of the LGREM was analyzed, and the main and secondary factors affecting the reliability of the LGREM are ranked in descending order of importance as overload coefficient, material density, and gravitational acceleration.