Multiobjective Optimization

Aerospace structures are usually operated in extreme and uncertain environment, and subject to the requirements of minimum weight, high performance and reliability. An interval-based game theory technique, coupled with interval-based nonlinear programming techniques is used for the optimum solution. The methodology is illustrated with two examples. The first one is a symmetric double wedge airfoil and the second one is a supersonic airplane wing. Three objectives, namely, the minimization of structural weight, minimization of energy and maximization of flutter Mach number for a specified flight condition are considered. The maximum stress, wing tip deflection, root angle of attack, natural frequencies and the stresses in the wing structure due to taxiing, gust and landing loads are suitably constrained. To deal with imprecision present in the system, probabilistic and interval approaches are used. Numerical examples are presented to illustrate the computational feasibility and effectiveness of the approaches. This work should be useful to students and researchers who are studying aerospace engineering during their preliminary design of an airplane structure.