| Abstrakt: |
The article presents the solution of the problem of synthesis of the optimal contour of a sealed shell with simultaneous search of its optimal design of the load-bearing arrangement. The weight of the sealed shell is minimized with a view to the constraints of fracture mechanics (for possible fatigue cracks in the sealed shell), constraints on static strength in the “landing” case of loading (preventing loss of stability of the constructiveness of the elements), design and dimensional constraints, and also constraints on the rigidity characteristics of the shell when it is subjected to lateral bending and torsion. We used 57 constraints in the form of inequalities with 17 independent variables: the thickness of the skin and the cross-sectional area of the stringers (in the upper, lower, and two lateral panels), the cross-sectional area of the rings and crack stoppers, the number of rings and stringers (in each panel), and also the coordinates of the places of over-lapping of the panels and their radii. Optimization was carried out by a combination of the methods of penalty functions and of steepest descent with changed “Fibonacci” step whose rational correction was applied by the present authors for the first time to the case of many variables. Examples of optimization are presented. The obtained convolutions of the optimal parameters can be used in the practice of planning sealed fuselages. |
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