Uncertainty Quantification of the ONERA 7A Rotor Performance and Loads Using Comprehensive Analysis

Quantification of blade stiffness uncertainties and sensitivities on rotor power and structural loads for the ONERA 7A rotor is established using the U.S. Army and ONERA rotorcraft comprehensive analysis tools. A stochastic-based approach is implemented to generate probabilistic bounds of the response outputs, including rotor performance and loads due to uncertainties in blade stiffness using 1) a Monte Carlo approach coupled directly with U.S. Army's rotorcraft comprehensive toolset, and 2) a surrogate of ONERA's rotorcraft comprehensive analysis solver using polynomial chaos expansions to efficiently predict the response outputs. The analysis showed that uncertainties in blade torsion, flap, and lag stiffnesses impact the predicted rotor power by a quantifiable amount. Significant uncertainties in peak torsion, flap, and chord bending moments are also confirmed. The sensitivities of the stiffness properties on response outputs using Sobol indices are also studied. The results show that total required power is exclusively sensitive to variability in torsion stiffness with no interaction effects with flap and lag stiffnesses. Sensitivities due to independent parameter effects and by combining with other parameters on peak structural loads are also examined. The analysis demonstrates the merits of integrating a stochastic, data-driven approach for uncertainty and sensitivity analyses in rotorcraft aeromechanics predictions.