This paper extends the independent point-wise density interpolation to the bimaterial to pology optimization to improve the structural static or dynamic proper ties.In contras t to the conventional elemental density-b...This paper extends the independent point-wise density interpolation to the bimaterial to pology optimization to improve the structural static or dynamic proper ties.In contras t to the conventional elemental density-based topology optimization approaches,this method employs an analysis-mesh-separated material density field discretization model to describe the topology evolution of bi-material structures within the design domain.To be specific,the density design variable points can be freely positioned,independently of the field points used for discretization of the displacement field.By this means,a material interface description of relatively high quality can be achieved,even when unstructured finite element meshes and irregular-shaped elements are used in discretization of the analysis domain.Numerical examples,regarding the minimum static compliance design and the maximum fundamental eigen-frequency design,are presented to demonstrate the validity and applicability of the proposed formulation and numerical techniques.It is shown that this method is free of numerical difficulties such as checkerboard patterns and the“islanding”phenomenon.展开更多
Solar-driven interfacial water evaporation technology offers a zero-carbon,sustainable solution for extracting clean water from seawater and wastewater,presenting an effective strategy to address the global water cris...Solar-driven interfacial water evaporation technology offers a zero-carbon,sustainable solution for extracting clean water from seawater and wastewater,presenting an effective strategy to address the global water crisis.This study has employed finite element simulation to investigate the solar interfacial evaporation process,elucidating the interactions between heat,water,and salt during evaporation.Additionally,the internal water channels of the evaporator are optimized and designed using topology optimization techniques.In this project,a cylindrical evaporator model with vertical micropores is developed from carbon-based polymer materials.The impact of pore diameter and spacing on the evaporation rate is analyzed,alongside the effects of thermal conductivity,solar radiation intensity,and ambient wind speed on the evaporator's performance.Simulations have revealed that with a pore diameter of 20μm and a spacing of 0.55 mm,the evaporator achieves the highest evaporation rate of 0.91 kg·m^(-2)·h^(-1).The findings indicate that smaller pore sizes substantially enhance the evaporation rate,while larger pore spacings initially increase,and then decrease the rate.Further optimization involves using 20μm-diameter round pores and adjusting the cross-sectional shapes of the pores based on topological configurations with a material volume factor of 0.5.The optimized structure demonstrates an evaporation rate of 2.91 kg·m^(-2)·h^(-1),representing a 219.78%increase over the unoptimized design.These optimized structures and simulation results provide valuable insights for future evaporator designs.展开更多
包含多个内嵌功能组件及支撑结构的多组件结构因其轻量化、多功能等优良特性被广泛应用于航空航天等领域.已有的多组件结构拓扑优化研究大多基于理想界面假设,忽略了材料连接界面可能发生的破坏.本文针对包含多个内嵌式功能性组件的结构...包含多个内嵌功能组件及支撑结构的多组件结构因其轻量化、多功能等优良特性被广泛应用于航空航天等领域.已有的多组件结构拓扑优化研究大多基于理想界面假设,忽略了材料连接界面可能发生的破坏.本文针对包含多个内嵌式功能性组件的结构,考虑连接界面的力学性能,对组件的形状、布局及支撑材料的拓扑进行协同优化,以实现多组件结构的优良承载性能.首先,基于超椭圆模型对内嵌组件的形状及布局进行显式的参数化描述,并构造其水平集函数表达;进而,结合组件及支撑材料的水平集拓扑描述、内聚力模型及扩展有限元方法(extended finite element method,XFEM),在固定网格下对随优化迭代不断演化的结构拓扑及连接界面的力学性能进行准确描述;进一步,建立水平集法框架下考虑界面力学性能的多组件结构拓扑优化列式,基于伴随变量法推导解析的灵敏度并采用梯度优化算法求解优化问题.本文采用该优化框架分别对内嵌组件的悬臂梁和MBB梁进行协同优化,在优化过程中,发现组件的初始布局对最终设计有很大的影响,并且可能导致不良结构.为了避免此情况,本文提出了两个阶段的优化策略,即首先对组件布局和形状进行优化,再进行结构和内嵌组件的协同优化.数值结果显示,在优化结果中功能性组件及界面通常分布于结构受压应力作用的区域,且连接界面最优形状呈现为曲率较小的光滑曲线,该设计避免界面发生拉伸及剪切破坏,有效提高了结构的承载力,同时也表明了本文所提出考虑连接界面力学性能拓扑优化方法的有效性.展开更多
The existence of a single topologically protected edge state in the first bulk bandgap for acoustic/elastic valley Hall insulators(VHIs)with zigzag interface configurations(ZICs)is well known.However,in this work,we s...The existence of a single topologically protected edge state in the first bulk bandgap for acoustic/elastic valley Hall insulators(VHIs)with zigzag interface configurations(ZICs)is well known.However,in this work,we show that an ultra-broadband edgestate pair in this bandgap can be created using the inverse design by topology optimization.The valley Hall insulator design increases the operational bandwidth 121%compared with an existing valley Hall insulator from recent literature and exhibits extreme field confinement,where more than 99%of the field intensity is concentrated within three unit-cells from the interface.One-way propagation and topological robustness towards small cavity defects are confirmed for the full bandwidth.The exploitation of such edge-state pairs of valley Hall insulators opens an avenue for realizing broadband confined edge modes.In tests for disorder and bend defects,we show that the additional ZIC,with a different operational frequency interval,encountered at the defects,degrades the transmission for bend and disorder defects which may prove significant for the application of VHIs.Through an alternative topology optimization method based on two ZICs,we further increase their common operational bandwidth.展开更多
基金The financial support of the National Natural Science Foundation of China(11425207,U1508209)is gratefully acknowledged.
文摘This paper extends the independent point-wise density interpolation to the bimaterial to pology optimization to improve the structural static or dynamic proper ties.In contras t to the conventional elemental density-based topology optimization approaches,this method employs an analysis-mesh-separated material density field discretization model to describe the topology evolution of bi-material structures within the design domain.To be specific,the density design variable points can be freely positioned,independently of the field points used for discretization of the displacement field.By this means,a material interface description of relatively high quality can be achieved,even when unstructured finite element meshes and irregular-shaped elements are used in discretization of the analysis domain.Numerical examples,regarding the minimum static compliance design and the maximum fundamental eigen-frequency design,are presented to demonstrate the validity and applicability of the proposed formulation and numerical techniques.It is shown that this method is free of numerical difficulties such as checkerboard patterns and the“islanding”phenomenon.
基金supported by the National Natural Science Foundation of China(No.52476064,No.52106085)National Key Research and Development Program of China(No.2022YFE0210200)+2 种基金China Postdoctoral Science Foundation(No.2023T160164)Natural Science Foundation of Heilongjiang Province(No.LH2023E043)Fundamental Research Funds for the Central Universities(No.2022ZFJH04,No.HIT.OCEF.2023021)。
文摘Solar-driven interfacial water evaporation technology offers a zero-carbon,sustainable solution for extracting clean water from seawater and wastewater,presenting an effective strategy to address the global water crisis.This study has employed finite element simulation to investigate the solar interfacial evaporation process,elucidating the interactions between heat,water,and salt during evaporation.Additionally,the internal water channels of the evaporator are optimized and designed using topology optimization techniques.In this project,a cylindrical evaporator model with vertical micropores is developed from carbon-based polymer materials.The impact of pore diameter and spacing on the evaporation rate is analyzed,alongside the effects of thermal conductivity,solar radiation intensity,and ambient wind speed on the evaporator's performance.Simulations have revealed that with a pore diameter of 20μm and a spacing of 0.55 mm,the evaporator achieves the highest evaporation rate of 0.91 kg·m^(-2)·h^(-1).The findings indicate that smaller pore sizes substantially enhance the evaporation rate,while larger pore spacings initially increase,and then decrease the rate.Further optimization involves using 20μm-diameter round pores and adjusting the cross-sectional shapes of the pores based on topological configurations with a material volume factor of 0.5.The optimized structure demonstrates an evaporation rate of 2.91 kg·m^(-2)·h^(-1),representing a 219.78%increase over the unoptimized design.These optimized structures and simulation results provide valuable insights for future evaporator designs.
文摘包含多个内嵌功能组件及支撑结构的多组件结构因其轻量化、多功能等优良特性被广泛应用于航空航天等领域.已有的多组件结构拓扑优化研究大多基于理想界面假设,忽略了材料连接界面可能发生的破坏.本文针对包含多个内嵌式功能性组件的结构,考虑连接界面的力学性能,对组件的形状、布局及支撑材料的拓扑进行协同优化,以实现多组件结构的优良承载性能.首先,基于超椭圆模型对内嵌组件的形状及布局进行显式的参数化描述,并构造其水平集函数表达;进而,结合组件及支撑材料的水平集拓扑描述、内聚力模型及扩展有限元方法(extended finite element method,XFEM),在固定网格下对随优化迭代不断演化的结构拓扑及连接界面的力学性能进行准确描述;进一步,建立水平集法框架下考虑界面力学性能的多组件结构拓扑优化列式,基于伴随变量法推导解析的灵敏度并采用梯度优化算法求解优化问题.本文采用该优化框架分别对内嵌组件的悬臂梁和MBB梁进行协同优化,在优化过程中,发现组件的初始布局对最终设计有很大的影响,并且可能导致不良结构.为了避免此情况,本文提出了两个阶段的优化策略,即首先对组件布局和形状进行优化,再进行结构和内嵌组件的协同优化.数值结果显示,在优化结果中功能性组件及界面通常分布于结构受压应力作用的区域,且连接界面最优形状呈现为曲率较小的光滑曲线,该设计避免界面发生拉伸及剪切破坏,有效提高了结构的承载力,同时也表明了本文所提出考虑连接界面力学性能拓扑优化方法的有效性.
基金supported by the China Scholarship Council(CSC)the Danmarks Grundforskningsfond(Grant No.DNRF147)。
文摘The existence of a single topologically protected edge state in the first bulk bandgap for acoustic/elastic valley Hall insulators(VHIs)with zigzag interface configurations(ZICs)is well known.However,in this work,we show that an ultra-broadband edgestate pair in this bandgap can be created using the inverse design by topology optimization.The valley Hall insulator design increases the operational bandwidth 121%compared with an existing valley Hall insulator from recent literature and exhibits extreme field confinement,where more than 99%of the field intensity is concentrated within three unit-cells from the interface.One-way propagation and topological robustness towards small cavity defects are confirmed for the full bandwidth.The exploitation of such edge-state pairs of valley Hall insulators opens an avenue for realizing broadband confined edge modes.In tests for disorder and bend defects,we show that the additional ZIC,with a different operational frequency interval,encountered at the defects,degrades the transmission for bend and disorder defects which may prove significant for the application of VHIs.Through an alternative topology optimization method based on two ZICs,we further increase their common operational bandwidth.
