Research On Reduced-scale Topology Optimization Method For Refined Design Of Large Complex Structures

Large complex structures are widely used in the national defense industry and civil life.The optimization of structure design is of great significance to the improvement of equipment performance.Topology optimization can obtain a high-quality configuration of the structure through the reasonable layout of materials.Using topology optimization methods to design large and complex structures can effectively improve the performance of the structure.However,due to the complexity of its own structure and many features,the large-scale complex structure has a huge scale of refined design and calculation based on topology optimization,which leads to difficulties in design and solution.In addition,there are sometimes situations where the boundary load is uncertain in the structure,and the attached auxiliary structure has a great influence on the optimal design,which makes it difficult to accurately describe the boundary conditions.Considering the influence of the attached structure will further lead to the calculation scale.rise.Therefore,a topology optimization method for scale-reduced needs to be established.The substructure can effectively reduce the amount of calculation under the premise of ensuring the calculation accuracy to improve the calculation efficiency.It is often used in the finite element analysis of large-scale complex structures.Aiming at the problem of refined design of large-scale complex structures,this paper introduces substructure technology into the topology optimization of large-scale complex structures,and studies and establishes a substructure-based scale-reduced topology optimization design method.Based on this,the accurate description of the boundary conditions of the aircraft’s reinforced frame and the corresponding topology optimization design are realized;for the design problems of multiple local areas in the complex large-scale structure,the topology optimization design method of the partition configuration is constructed.Specific research contents and results are as follows:(1)Topology optimization design method with scale-reduced based on substructure.This paper proposes a substructure-based scale-reduced topology optimization design method,which can be used for the refined design of large and complex structures.In order to accurately describe the boundary conditions of the structure and reduce the calculation scale of the degrees of freedom,this paper firstly establishes the analysis method of the static condensation degrees of freedom of the substructure,and proposes an equivalent way to describe the boundary conditions.Using the proposed method,the attachment structure that has a greater impact on the structural design domain can be used as a substructure for dimensionality reduction processing,and the boundary conditions of the structural design domain can be equivalently described by retaining the condensed node information.This reduces the number of structural degrees of freedom,reduces the calculation scale,and achieves the goal of scale-reduced topology optimization design.The last few numerical examples show that the proposed method is effective for improving the efficiency of the topology optimization design of large and complex structures.(2)The topological optimization design of the reinforced frame structure in the middle section of the aircraft fuselage.The stress environment of the large and complex structure of the mid-section reinforced frame of the aircraft fuselage is complicated.The load boundary conditions such as shear force and bending moment are mainly derived from the surrounding structure,and the refined design and solution of topology optimization are difficult.Aiming at this complex structure design problem,this paper uses the established substructurebased scale-reduced topology optimization design method,considering the influence of the auxiliary structure connected to the reinforced frame,and adopts the method of substructure aggregation to strengthen the frame attachment structure to obtain an accurate description of the reinforced frame boundary conditions.In this way,the topology optimization design of the reinforced frame structure in the middle section of the aircraft fuselage is realized,and the effectiveness of the method for improving the efficiency of the local structure topology optimization design is further verified.(3)Topology optimization method of complex structure partition configuration based on substructure.Large-scale and complex structures often have multiple local area design problems.Because of the large number of boundary nodes in each area,directly adopting the substructure-based dimensionality reduction topology optimization method to design will still be time-consuming and inefficient.This paper proposes a topology optimization method for the partition configuration of large complex structures,with structural compliance as the goal,reducing the calculation scale while enhancing the structural performance as much as possible,and improving the efficiency of optimization.The main strategy is to first design one of the regions based on the substructure topology optimization method.Based on the initial topology optimization results of the region,perform the topology optimization of the next region,and so on,until the configuration design of each region is completed.Then,based on the optimization results of other regions,the first region is optimized for the second time,and iteratively,and finally a more accurate topology optimization design result of the partition configuration is obtained.On the one hand,this method can reduce the calculation scale so that it can run on an ordinary computer and improve efficiency;on the other hand,it reduces the influence of separate design on the optimal topology optimization results.