Asymmetric Coupled-Adjoint Optimization Using a Structural Surrogate Under Wing Sizing and Cruise Conditions

Prior work from the authors presented a new method for addressing the computational and organizational challenges of wing aerostructural optimization at the preliminary design stage. This new method employed a one-shot surrogate model of a structural suboptimization embedded in a coupled-adjoint formulation and is herein referred to as asymmetric coupled-adjoint optimization using a structural surrogate (ACOSS). However, this earlier work only investigated the method under a single cruise condition, and it is of interest to consider separate multidisciplinary analyses (MDAs) for both the sizing and cruise conditions as a further development of the methodology. As shown herein, the cruise MDA is dependent on the sizing MDA since the surrogate model represents a structural sizing process. This dependence is also characteristic of other architectures that include a structural suboptimization. To capture this dependence, an expanded coupled-adjoint formulation for ACOSS is presented in this work. The methodology is demonstrated on an aerostructural optimization of the NASA Common Research Model wing. The ACOSS architecture and adjoint methodology are also further generalized to cases with multiple sizing load cases and multiple cruise cases.