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Evolutionary structural optimization of multiple load case generic aircraft components

Avgın, Murat Atacan
Structural optimization is achieving the best objective function from a predefined medium, well bounded by constraints. Optimization methods have been utilized on different engineering applications to minimize the conceptual design effort that creates the necessity of new optimization techniques. Evolutionary Structural Optimization (ESO) is a topological optimization algorithm, which is defined as removing of inefficient elements from a design domain. ESO stress based method is applied to linear elastic, isotropic aircraft components for multiple load case. The bulk structure is modeled and discretized into three dimensional solid hexahedron or tetrahedron mesh, afterwards constraints, load and boundary conditions are defined in MSC.PATRAN. MSC.NASTRAN is utilized as finite element solver. The stress results are collected and evaluated by program developed in MICROSOFT VISUAL BASIC. The elements which are below the stress limit are eliminated. The remaining elements are operated after increasing the stress limit. The iteration process continued until prescribed rejection ratio is reached. Well known examples in literature are solved using program code and similar results are obtained which is a check for the code developed. Four generic aircraft components, the clevis, the lug, the main landing fitting and power control unit fitting were structurally optimized. The stress distribution in optimized results and existing aircraft designs are compared.