| Aerospace structures are usually operated in extreme and uncertain environments, and subjected to the requirements of minimum weight, high performance and reliability. A procedure is described for the interval analysis-based automated optimum design of airplane wing structures subjected to multiple behavior constraints. Three objectives, namely, the minimization of structural weight, minimization of energy and maximization of flutter Mach number for a specified flight condition are considered in the problem formulation. The maximum stress, wing tip deflection, root angle of attack, the natural frequencies of the wing structures and the stresses induced in the wing structure due to taxiing, gust and landing loads are suitably constrained. To deal quantitatively with imprecision and uncertainty present in the system, probabilistic and interval approaches are used for finding the stresses. Numerical examples are presented to illustrate the computational feasibility and effectiveness of the approaches presented. The procedure outlined is expected to be useful during preliminary design of an airplane structure. A sensitivity analysis is performed on the optimization results corresponding to the finite element model. The thesis is divided into thirteen chapters and five appendixes. |
