【作者】 张帆；

【导师】 王宪杰；

【作者基本信息】 云南大学 ， 建筑与土木工程（专业学位）， 2022， 硕士

【摘要】 随着大跨空间结构的广泛应用和工程师们对新型结构的不断追求,空间节点的样式也随之不断革新。而力与形的完美组合,将是空间结构形式在艺术表现上的最高境界。拓扑优化方法旨在一定目标下寻找结构材料的最优分布位置,在设计时往往能够设计出造型奇特而满足目标需求的结构,将其应用于空间结构节点的设计上,在一定程度上能够解放设计师的想象空间,设计出造型丰富的空间结构。同时,当前增材制造技术的不断突破,也使得拓扑优化后的复杂节点也有了制造的可能。当前增材制造和拓扑优化在空间节点的应用上还需要不断探索,除了优化方法的应用研究,还需要考虑增材制造技术所制造产品的性能问题,节点优化设计后能否制造,以及制造和设计的性能是否一致,都是亟待解决的问题。为此,本文针对空间节点探索了算法编程、有限元求解以及增材制造协同的拓扑优化-制造一体化集成方法,研究了当前增材制造技术在打印方向上出现材料各向异性的问题,以及考虑自支撑制造约束的优化方法,为空间结构节点找形提供一套高效、可行的创新解决方案。主要研究内容和结论如下:(1)基于双向渐进结构优化方法(BESO),探索了空间节点优化-增材制造的全过程方法。与商用有限元软件自带的变密度法优化结果对比之下,该软件集成方法所优化的剪力工况空间节点模型最大应力能够降低9.8%,最大变形能够降低23.2%;组合工况空间节点模型最大应力能够降低21.1%,最大变形能够降低33.6%,性能明显提升。(2)本文基于工程弹性常数研究了材料各向异性对结构的影响,研究发现增材制造试件各个方向的力学性能存在差异,不同方向的最大最小弹性模量相差24.1%;屈服强度相差20.9%,存在较明显的各向异性。将各向异性属性代入优化求解,计算得到,材料的各向异性属性会显著改变优化结果的造型;存在最大刚度的优化结果;不同结果的最大最小刚度相差15.1%。(3)研究了结构的自支撑方法,通过对结构0-1显式骨骼的表征,结合三角形边界滤波器和三角锥边界滤波器,使得添加的支撑在迭代中能够保留。本文对空间节点算例进行了优化应用,经过支撑算法计算后得到的优化结果,最大变形不超过4.1%;最大体积变化不超过3.1%。性能牺牲较少,优化结果基本能够达到自支撑效果,在成型试验中表现较好。更多还原

【Abstract】 With the wide application of large-span space structures and the continuous pursuit of novel structures by engineers,the styles of space nodes are constantly innovating.The perfect combination of force and shape will be the highest state of space structure form in art.The topology optimization method aims to find the optimal distribution position of structural materials under a certain target.In the design,it is often possible to design a structure with a peculiar shape that meets the target requirements.It can be applied to the design of spatial structure nodes to a certain extent.Liberate the designer’s imagination and design a spatial structure with rich shapes.At the same time,the continuous breakthrough of the current additive manufacturing technology also makes it possible to manufacture complex nodes after topology optimization.The application of additive manufacturing and topology optimization in space nodes needs continuous exploration.In addition to the application research of optimization methods,it is also necessary to consider the performance of products manufactured by additive manufacturing technology.Whether the node can be manufactured after the optimized design and whether the performance of manufacturing and design are consistent are all issues that need to be solved urgently.To this end,this paper explores algorithm programming,finite element solution,and additive manufacturing collaborative topology optimization-manufacturing integration method for space nodes.The problem of material anisotropy in the printing direction of the current additive manufacturing technology is studied,and the optimization method considering the constraints of self-supporting manufacturing is studied to provide a set of efficient and feasible innovative solutions for the form-finding of spatial structure nodes.The main research contents and conclusions are as follows:(1)Based on the bidirectional incremental optimization method(BESO),a full-process method of spatial node optimization-additive manufacturing is explored.Compared with the optimization results of the variable density method that comes with the commercial finite element software,the maximum stress and maximum deformation of the space node model under the shear force condition optimized by the software integrated method can be reduced by 9.8% and 23.2%.The maximum stress of the model can be reduced by 21.1%,the maximum deformation can be reduced by 33.6%,and the performance is significantly improved.(2)In this paper,based on the engineering elastic constant,the effect of material anisotropy on the structure is studied.It is found that there are differences in the mechanical properties of the additive manufacturing specimens in all directions.The maximum and minimum elastic moduli in different directions differ by 24.1%;obvious anisotropy.Substitute the anisotropic properties into the optimization solution.The calculation shows that the anisotropic properties of the material will change the shape of the optimization results.There is an optimization result with the maximum stiffness,and the maximum and minimum stiffness of different results differ by 15.1%.(3)A self-supporting method for structures is studied by characterizing the 0-1 explicit bones of the structure,combined with a triangular boundary filter and a triangular pyramid boundary filter so that the added support can be preserved in iterations.In this paper,the space node calculation example is optimized and applied.The optimization results obtained after the support algorithm calculation show that the maximum deformation does not exceed4.1%;the maximum volume change does not exceed 3.1%.The performance sacrifice is less,and the optimization results can basically achieve the self-supporting effect,which performs well in the molding test.更多还原