Integrated Layout And Topology Optimization Design Of Multi-frame And Multi-component Fuselage Structure Systems

The research of this work is motivated by the densified,integrated and light-weight design of the aerospace structural systems.Based on the traditional integrated layout and topology optimization design of the multi-component structural systems,we present the design formulation dealing with the integrated layout and topology optimization design of the multi-frame and multi-component fuselage structure systems.We improve the mathematic model of the traditional optimization design method which containing a large number of non-overlapping constraint conditions into a penalty function based formulation involving no non-overlapping constraint conditions.The proposed formulation is applied to solve the optimization of the typical multi-frame and multi-component fuselage structure systems.The innovation points of this work are marked as followings:Firstly,the improved penalty function based method is proposed to deal with the integrated layout and topology optimization design of a typical multi-component structural system which contains hundreds of non-overlapping constraints formulated by the finite-circle method.In the traditional method,it is difficult to obtain a feasible design of the same system.In the improved penalty function based formulation,hundreds of non-overlapping constraints are added into the objective function by a proposed controllable and intuitive penalty term.By using this method,the optimizer will not deal with hundreds of separated non-overlapping constraint conditions and the numbers of constraint conditions decrease sharply.The analysis of the design sensitivities of the proposed formulation are given in this work and the validity and feasibility of the proposed penalty function based formulation is tested by several numerical examples.Secondly,the idea of the integrated layout and topology optimization design of the multi-frame and multi-component fuselage structural system is proposed.Here,the movable frames are introduced into the fuselage structural system.The layouts of the frames as well as the topological configurations of the frames are taken into consideration.During the optimization design procedure,there are four kinds of design variables,i.e.,the pseudo-density variables of the main structure and of the movable frames,the geometrical design variables of the movable frames and components.The connections among components,frames and main structure are simulated by using the multi-point constraints.The proposed penalty function based formulation is implemented here to deal the optimization design procedure.The centroid position constraint is taken into account to maintain the balance of the fuselage structural system.The influences of different centroid position constraints,material properties of the frames,material usages of frames and main structure are discussed in detail.The optimized design result indicates that the layouts of the movable frames and their topological configurations can make a difference to the final optimized design result.And the proposed new idea in dealing with the layout and topology optimization design of the multi-frame and multi-component fuselage structural systems is verified to be valid and it brings much freedom into the design of the multi-frame and multicomponent fuselage structural systems.Finally,the proposed formulation is applied into the layout and topology optimization design of the typical multi-frame and multi-component fuselage structural systems in the aerospace industry.It is indicated that the components and frames work with each other to decrease the burden of the main structure to obtain a better performance of the multi-frame and multi-component fuselage structural systems.And this work makes an essential foundation for the integrated design of the complicated fuselage structural systems.