Wing Optimization Using Curvilinear Spars and Ribs (SpaRibs), and Curvlinearly Stiffened Panels

We have developed two optimization frameworks, EBF3SSWingOpt and EBF3PanelOpt to design wings with curvilinear spars and ribs (SpaRibs), and curvlinearly stiffened panels, respectively. The curvilinear stiffening tries to utilize the larger design space created by additive manufacturing techniques like Electron-Beam-Free-Form-Fabrication, Friction Stir Welding, and Selective Laser Sintering. Structural loads of future aerospace vehicles may not be well characterized using our knowledge-based databases, so medium-fidelity software like Msc.Patran (geometry and meshing), and Msc.Nastran (finite element analysis) are integrated in EBF3PanelOpt and EBF3SSWingOpt frameworks. In EBF3SSWingOpt, the shape and sizes of SpaRibs, and skin thickness are optimized, but the optimization is yielding wing with too many SpaRibs. The EBF3SSWingOpt minimizes the wing mass with the constraints on flutter velocities and von Mises stress for different flying conditions. Similarly, EBF3PanelOpt minimizes the mass of the stiffened panel with the constraints on buckling, von  Mises stress and crippling of the stiffeners. The utilization of EBF3PanelOpt along with EBF3SSWingOpt requires modification of EBF3PanelOpt such as non-uniform in-plane loads and application of boundary conditions as displacements obtained from EBF3SSWingOpt. The panels for EBF3PanelOpt would be extracted from the intersection of wing-skins, and SpaRibs. Different levels of interactions between EBF3SSWingOpt and EBF3PanelOpt are possible depending upon the computational cost. During these interactions, panels could be un-stiffened, straight stiffened, curvilinearly stiffened (stiffener end-points fixed), and curvilinear stiffened (end-points of the not fixed). The application of the interaction of EBF3SSWingOpt and EBF3PanelOpt results in substantial mass saving as compared to stand alone application of EBF3SSWingOpt.