Reliability Analysis for Aero Engine Gear Considering Dependence of Multiple Failure Modes Based on Copula

A transmission gear commonly has multiple dependent failure modes. The reliability analysis methods that ignore the dependence effect often have substantial errors. This paper constructs the limit state functions of failure modes based on the stress-strength interference theory, characterizes the dependence among multiple failure modes with the help of Copula theory, transforms the multidimensional dependence problem into several two-dimensional Copulas based on Vine Copula, and uses square Euclidean distance to identify the optimal function. Using this method, a D-Vine Copula model is established for the spur gear in an aero engine accessory transmission system to carry out the gear reliability analysis considering the dependence of multiple failure modes, which demonstrates the rationality and effectiveness of the proposed method.