Forward Probabilistic Methodology for Static Damage Initiation and Vibratory Characteristics of Laminated Composite Fan Blade With Multiscale Aleatory Uncertainties

Abstract An investigation is conducted to ascertain the feasibility of using integrated probabilistic design to evaluate structural integrity of composite fan blade used in advanced high-bypass-ratio turbofan engines. The structural probability analysis obtains statistical properties at the macroscopic level under multiscale uncertainties and quantifies the failure probabilities of design criteria against static damage initiation and resonance margins. Due to the geometry and laminate design complexity, this represents an extremely intricate but novel application for forward uncertainty quantification. Nonintrusive polynomial chaos expansion (PCE), Gaussian process, and field metamodel are established and validated. A suitable compromise among affordable computation cost and prediction accuracy is fulfilled. For field quantities, uncertainty of ply stresses and modal displacement are evaluated through field statistical measures. Variance-weighted average of the explained variance is evaluated for ply stress by synthetic random field discretization. It shows that fiber orientation explains 81.1% variance of ply stress field and covers a great layer extent, whereas ply thickness is rather small and has a slight influence on field variance. Ply stress field is a non-Gaussian and nonstationary random process. At last, static damage and resonance frequency design are fully illustrated in probabilistic manner. Failure probability of static damage is 1.48 × 10−4, and the second bending mode has the maximum resonance probability, which could help the engineer understand the potential risks of structural design for composite fan blades.