Research On Folded Shell Structure Based On Topology Optimization

The single-layer reticulated shell structure is a curved grid structure composed of rods.The essence of the reticulated shell structure is the latticeization of the thin-shell structure,which not only has the advantages of reasonable force and lightness and aesthetic appearance of the thin-shell structure,but also achieves the goals of industrialized production and assembly construction.The single-layer reticulated shell structure is one of the most widely used forms of large-span spatial structures,and it has outstanding advantages in the aspects of architectural appearance,structural force performance,and production and construction.At present,the scholars propose and design the geometry of the single-layer reticulated shell structure based on the mathematical curve set by man,instead of forming its geometric shape based on the optimal mechanical properties.The topology optimization theory takes the optimal mechanical performance as the optimization goal,and automatically forms a reasonable geometric shape of the force according to the constraints and the optimization goal.Breaking through the traditional design must first propose the structure selection,and then perform the force analysis and improvement process.Through the topology optimization of the shell structure to seek the best force transmission path,thereby significantly reducing the system's weight,build a more reasonable structure of the system.Due to the thinness of the single-layer reticulated shell structure,it generally has the vertical stiffness and the relatively poor stability of the characteristics.For the problem of poor vertical stiffness and stability of single-layer spherical reticulated shell structures,topology optimization method was used to study its optimal morphology.Firstly,OptStruct is used to optimize the spherical shell structure,and a new type of folded shell structure is obtained.Then,based on the results of topology optimization of the spherical thin shell structure,a single-layer spherical folded shell structure is constructed.Then parametric modeling of a single-layer spherical latticed shell structure was performed using the parametric language of ANSYS.In this paper,the mechanical properties of the new single-layer spherical folded shell structure and the mechanical properties of the traditional single-layer spherical reticulated shell structure are compared and analyzed from three aspects.(1)By comparing the flexibility of four kinds of single-layer spherical reticulated shell structures under the action of three kinds of loads alone and the three kinds of loads,the paper select two types of structures with less flexibility under the action of three kinds of loads as the structure analysis model and then analyzed the single-layer spherical folded shell structure and single-layer spherical reticulated shell structure stiffness difference analysis and the geometric parameters of the single-layer spherically folded shell structure were optimized.(2)The differences in the stability performance of the single-layer spherical folded shell and the single-layer spherical reticulated shell structure under the two loading conditions were compared and analyzed.The effects of single bar instability and initial defects on the stability of the single-layer spherical reticulated shell structure and the single-layer spherical reticulated shell structure are considered in detail.(3)The paper compare and analyze the differences of the first fifty-order natural vibration frequency and the first eight vibration modes of the single-layer spherical folded shell structure and the single-layer spherical latticed shell structure,and the difference of elastoplasticity time-history dynamic response under the action of one-dimensional earthquake and multidimensional earthquake considering the effect of gravity.The results show that the new single-layer spherical folded shell structure based on the results of the topological optimization of thin-shell structures has not only improved vertical stiffness but also geometric initial defects and asymmetrical loading compared with the traditional single-layer spherical reticulated shell structures.The sensitivity is also significantly reduced,and it is a new type of long-span space structure with excellent performance.