Abstract: The influence of components’ life related failure (an important related failure) on wind turbines gearbox reliability was taken into consideration during the study of system reliability of the 1.5 MW wind turbine gearbox. To begin with the components, the dynamic reliability model of mechanical components is introduced to compute the reliability of the components. The curves of life distribution functions are obtained through the relationship between components’ reliability and life distribution functions, then, life distribution function of each component can be estimated by sampling method and least square method. The frequency histograms of related components are drawn based on the life distribution function of the main failure components of wind turbine gearbox, the Copula reliability model of wind turbine gearbox under components’ life related conditions is established with appropriate Copula functions combined with the relative theory of Copula function and Sklar theorem. No need is required to determine the joint distribution function of random variables with the model built through this method. In addition, not only the limitation of linear correlation assumptions between each component’ life distribution is avoided, but also the multifarious integral operation is replaced with simple Copula function operation. The dynamic reliability of wind turbine gearbox is figured out with parameters which reflect the degree of correlation between each life distribution estimated with Matlab R2012b software. The varying pattern of the reliability of wind turbine gearbox system to time and parameters mentioned above is given and the theory for the design, manufacture and maintenance of wind turbine gearbox is provided.

Key words: Copula function, fatigue life, related degree parameters, relevant failure, system reliability analysis