MULTIDISCIPLINARY OPTIMIZATION OF PRO COMPOSITE STRUCTURAL LAYOUTS OF HIGH LOADED AIRCRAFT CONSTRUCTIONS
The concept of structure layout based on hybrid lattice rods panels is presented. The algorithm for calculation of rational parameters is developed. The optimization procedure of hybrid lattice rods panels, based on the developed algorithm, considering strength, buckling and heat insulation requirements have been developed. The results of flying wing fuselage panel weight estimation are presented. 1 General Introduction Composite materials has been using for lightly loaded parts of aircraft structure, such as slats, wing flaps and fairings for a long time. The main feature of these structures is low active strains level (less than 0.3% At present time they try to use composite materials for high loaded parts of aircraft structures. The basic load bearing element of current high loaded composite structures is laminated skin. According to a number of investigations, this type of load bearing elements, due to heterogeneity and large difference of components' mechanical properties, has some essential disadvantages: low ultimate deformation of package, high sensitivity to the impact, low reparability [1] 2 Lattice and truss structures A method to solve the problems mentioned above is seen in designing the structure based on layouts considering features of composite materials and allowing to use potential of highstrength carbon fibers. Such layouts are called "pro composite" The main idea of procomposite layouts is maximum alignment of main force flow and carbon fiber directions [1] The example of structure based on procomposite layout is lattice structure. The main load bearing element of this type of structure is composite UD rib, in which carbon fibers are directed coaxial with rib. Such layout allows to reduce level of internal stress concentrations and, due to this fact, increase ultimate deformations. However, reduction of strength of UD rib after impact is larger than for laminated skin. It should be noticed that the problem of protection for UD ribs can be effectively solved, unlike for laminated skin. A question about repairing of lattice structure is stay opened [2][3] Truss structure based on load bearing composite rods, whose fiber direction is very close to axis of rod, is another example of procomposite layout. Rods, as lattice ribs, have a bigger than laminated skin ultimate strains. Protection of rods from impact is very simple. A large quantity of subunits allows repairing the truss structure by replacement a broken part by a new one without weight increase [4] MULTIDISCIPLINARY OPTIMIZATION OF PRO COMPOSITE STRUCTURAL LAYOUTS OF HIGH LOADED AIRCRAFT CONSTRUCTIONS Ivan Mareskin Moscow Institute of Physics and Technology (MIPT)