Reliability analysis for close position accuracy of gear door mechanism based on Importance Sampling

Methods of FOSM (first order and second moment) or MCS (Monte Carlo simulation) are not suitable for some complex mechanisms, especially those with the characteristics of high dimensions, low failure rate and highly nonlinear. Gear door mechanism is one of the most important subsystems in landing gear system of the aircraft, and many of its components and factors affect the close position accuracy. In this paper we focus on the close function failure mode of the gear door mechanism. At first the dimensional error of door's components and the mismatch error of hinges are defined as the basic random variables, the reliability model and performance function for close position accuracy of the gear door mechanism can be constructed. Then the IS (Importance Sampling) method is used to simulate samples for the performance function. At last, the reliability for the close position accuracy of gear door mechanism and its sensitivity about distribution parameters of every basic variable can be evaluated based on the simulation result. The result of analysis is helpful for its designing, design modification, reliability estimation and some problems that should be noticed in its employment and maintenance.