Fatigue damage evaluation of structure with uncertain parameters under random load

Based on improved interval analysis and spectral fatigue estimate methods, two new approaches, full combination method and simplified method, are presented to evaluate fatigue damage of structure with uncertain parameters under stationary Gaussian load, in which interval variables are introduced to describe uncertain parameters of structural systems. In proposed methods, uncertain parameters of structure are defined by interval parameter models, and randomness of external loads is described by power spectral density. Interval frequency response functions of structure and dynamic response intervals of uncertain structure under stationary Gaussian load are explicitly expressed by the Rational Series Expansions. The proposed full combination method wholly combines the bounds of uncertain parameters in the fatigue estimation stage, which can accurately estimate intervals of expected fatigue damage rate of structure with uncertain parameters. The simplified method properly combines the bounds of uncertain parameters, which approximately calculates intervals of expected fatigue damage rate through explicit expression. Finally, numerical examples are used to illustrate the accuracy and applicability of the proposed methods. It is shown that both methods have high calculation accuracy and greatly reduce the amount of calculation. © 2020, Nanjing Univ. of Aeronautics an Astronautics. All right reserved.