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Micro and nanolattice fabrication using projection micro litho stereo exposure additive manufacturing techniques and synchrotron X-ray 3D imaging-based defect characterization

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Science China(Technological Sciences) 2020年第4期63卷 561-570页

作者： HU WenXia LIU Liwu wu wenwang XI Li LENG JinSong FANG DaiNing Institute of Advanced Structure Technology Beijing Institute of TechnologyBeijing 100081China Department of Astronautical Science and Mechanics Harbin Institute of TechnologyHarbin 150001China National Key Laboratory of Science and Technology on Advanced Composites in Special Environments Harbin Institute of Technology(HIT)Harbin 150080China Department of Mechanical Engineering Massachusetts Institute of TechnologyCambridge MA 02139USA

Synchrotron radiation X-ray micro-computed tomography(SR-μCT)is a 3D imaging technique that is widely employed for the characterization of defects in advanced materials and *** this study,we characterize several typical defects in octettruss and re-entrant 3D lattice structures by using SR-μ*** 3D micro-lattice structures are manufactured using projection micro litho stereo exposure(PμLSE)additive manufacturing *** as-fabricated 3D lattice samples are characterized using optical microscopy,and subsequently,by SR-μ*** more,a statistical analysis is performed to characterize the surface roughness and internal defects qualitatively,whereby the statistical geometrical parameters of struts along different directions and strut joints are analyzed and ***,several typical defects are identified:(1)holes at the joints of the strut and irregular diameter deviations of the strut in the octet-truss lattice structure;(2)irregular diameter variations,bulges,dislocations,grooves,accumulations,and torsion in the re-entrant lattice *** of these defects are related to the building direction,the weight of the structure,bubbles,dust,and impurities during the PμLSE additive manufacturing process.

关键词： synchrotron radiation X-ray additive manufacturing lattice structures defect characterization

Damage evolution of PμLSE additive-manufactured micro-lattice metastructures: Synchrotron radiation 3D tomography image-based analysis

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Science China(Physics,Mechanics & Astronomy) 2020年第10期63卷 71-80页

作者： QingLiang Zeng wenwang wu WenXia Hu Li Xi Ran Tao DaiNing Fang Institute of Advanced Structure Technology Beijing Institute of TechnologyBeijing 100081China Beijing Key Laboratory of Lightweight Multi-functional Composite Materials and Structures Beijing 100081China Department of Engineering Mechanics School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China

The manufacturing of additives with projection micro litho stereo exposure(PμLSE)has provided an opportunity for the fabrication of metastructures with complex microstructures at micro-nano ***,the performance evaluation of as-fabricated metastructures is *** benefit of synchrotron radiation-based 3 D imaging techniques and advanced image processing methods makes it is feasible to study fabrication defects and damage processes of micro-nanoscale bodycentered cubic(BCC)lattices manufactured with Pμ***,synchrotron radiation technology is used to capture the structural features inside the micro-lattice ***,several types of statistical defects-based image finite element models are adopted to analyze the failure process of the structure under compression ***,comparisons between in situ experiments and numerical simulation results are performed for *** method of the combined non-destructive testing of synchrotron radiation and image finite element technology provides a robust technique for evaluating the performances of additive-manufactured micro-lattice with complex microstructures.

关键词： synchrotron radiation X-ray micro-lattice image finite element method in situ compression experiment

Mechanics and Wave Propagation Characterization of Chiral S-Shaped Auxetic Metastructure

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Acta Mechanica Solida Sinica 2022年第4期35卷 571-586页

作者： Qingsong Zhang Wenjie Hong Jianfei Xu Yuhang Zhang Suhang Ding wenwang wu Re Xia Key Laboratory of Hydraulic Machinery Transients(wuhan University) Ministry of EducationWuhan430072China School of Naval Architecture Ocean and Civil EngineeringShanghai Jiao Tong UniversityShanghai200240China Institute of Advanced Structure Technology Beijing Institute of TechnologyBeijing100081China Hubei Key Laboratory of Waterjet Theory and New Technology Wuhan UniversityWuhan430072China

Auxetic metastructures have attracted tremendous attention because of their robust multifunctional properties and promising potential industrial *** paper studies the in-plane mechanical behaviors of a chiral S-shaped metastructure subjected to tensile loading in both X-direction and Y-direction and wave propagation properties using the finite element(FE)*** relationships between structural parameters and elastic behaviors are also *** results indicate that the orientation of chiral S-shaped metastructure under tensile loading in the X-direction exhibits higher auxeticity and ***,the band structures and the edge modes of each band gap of the chiral S-shaped metastructure are explored,and the relations between band gap properties and structural parameters are also systematically ***,we explore the wave mitigation of the chiral S-shaped metastructures by regulating the structural ***,the transmission properties of the finite chiral S-shaped periodic metastructures are studied to confirm the results of band gap *** study promotes the engineering application of vibration isolation of chiral structures based on the band gap theory.

关键词： Auxetic metastructures Mechanical properties Band gaps Wave mitigation

Fracture toughness and destructive mechanism of ductile nanoporous metallic glass and its crystal-impregnated nanocomposite

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Science China(Technological Sciences) 2023年第11期66卷 3328-3342页

作者： ZHANG YuHang XU JianFei HU YiQun SU Lei DING SuHang wu wenwang XIA Re Key Laboratory of Hydraulic Machinery Transients(wuhan University) Ministry of EducationWuhan 430072China Department of Engineering Mechanics School of Naval ArchitectureOcean&Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China

Nanoporous metallic glasses(NPMGs)and crystalline/amorphous nanocomposites exhibit superior ductility over bulk macroscopic metallic glasses(MGs).Their fracture behaviors remain a mystery due to experimental technical *** this work,the fracture behaviors of pre-cracked NPMGs and crystal-impregnated nanoporous metallic glasses(CINPMGs)are investigated through large-scale molecular dynamics simulations,and the MG and crystal phases are amorphous Cu_(50)Zr_(50)and crystalline B2CuZr,*** toughness is determined by simultaneously considering the surface energy and plastic dissipated *** results confirm the excellent plasticity of both the pre-cracked NPMGs and *** progressive necking and ductile rupture of ligaments are responsible for generating NPMGs with prominent ductility and fracture ***,secondary cracking is also triggered,which can consume energy without extending the major crack,thus further improving fracture *** is also found that the fracture toughness of NPMGs can be improved by increasing the solid fraction of MG,and linear relation between fracture toughness and solid fraction can be *** impregnation effectively inhibits global failure as the crystal phase shields the individual amorphous *** plastic flow characterized by shear bands is observed in CINPMGs,and this homogeneous global deformation is facilitated by the crystalline/amorphous ***,the fracture toughness of CINPMGs is higher than that of the constituent single phases,regardless of the volume fraction of each *** material charts manifest that these two types of materials demonstrate promising potential in the material selection library for advanced structural design.

关键词： nanoporous metals crack fracture toughness nanocomposites metallic glasses

Mechanical design and energy absorption of 3D novel hybrid lattice metamaterials

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Science China(Technological Sciences) 2021年第10期64卷 2220-2228页

作者： ZHANG Peng Biligetu QI DeXing XUE Rui LIU Kai HUANG ZhiXin wu wenwang LI Ying State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China Beijing Key Laboratory of Lightweight Multi-functional Composite Materials and Structures Institute of Advanced Structure TechnologyBeijing Institute of TechnologyBeijing 100081China Department of Engineering Mechanics School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China Inner Mongolia First Machinery Group Co.Ltd. Baotou 014000China

In this paper,three-dimensional(3D)novel hybrid lattice structures with exceptional mechanical properties and energy absorbing performances were proposed,and experimental and finite element simulation comparisons were performed to demonstrate their potential in mechanical ***,different types of basic cubic unit cells were designed for constructing three types of novel hybrid metamaterials,in which stepped circulation of different unit cells was conceived to generate architected ***,quasi-static compression experiments and finite element simulations were performed to study the deformation process and failure mechanisms of as-fabricated hybrid *** energy absorption efficiency,specific energy absorption(SEA)indicators,and energy absorption capabilities of different hybrid lattice metamaterials were compared and *** results show that the deformation mechanisms of novel hybrid lattice were beneficial for generating remarkable elevated densification strain,and the energy absorption efficiency can be tailored by altering the types or sizes of basic unit ***-hardening and bilinear features were also obtained.

关键词： hybrid lattice quasi-static compression densification strain energy absorption strain hardening bilinear

Efficient model for the elastic load of film-substrate system involving imperfect interface effects

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Theoretical & Applied Mechanics Letters 2020年第6期10卷 390-404页

作者： wenwang wu Huabin Yu Rui Xue Tian Zhao Ran Tao Haitao Liao Zhongdong Ji School of Naval Architecture Ocean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China Institute of Advanced Structure Technology Beijing Institute of TechnologyBeijing 100081China Institute of Mechanics Chinese Academy of SciencesBeijing 100190China

In this paper,an efficient calculation method based on discrete Fourier transformation is developed for evaluating elastic load induced elastic deformation fields of film-substrate *** use of 2 D discrete Fourier transformation,the elastic fields induced by Hertz load is harvested in frequency domain,and the displacement and stress fields across the interface are enforced to satisfy the elasticity conditions for each Fourier *** arbitrary distributed stress field at free surface plane of the three types of film-substrate systems,unique resultant elastic field within the can be *** load of half space,elastic film on elastic substrate,elastic film on rigid substrate system and elastic film-substrate system with three types of imperfect interface models are investigated:(1)the spring-like imperfect interface model which can be described as:u^fk|zf=-h-u^sk|z^s=0=KTσKZ and u^fz|zf=-h-u^sz|z^s=0=KNσZZ;(2)the dislocation-like interface model,where interface displacement and stress components relation can be described as:u^fi|zf=0=k^uiju^si|z^s=0 andσ^fiz|z^f=0=σ^siz|zf=0=σ^siz|z^s=0;(3)the force-like interface model,where interface displacement and stress components relation can be described as:u^fi|z^f=0=u^si|z^s=0 andσ^fiz|z^f=0=k^tijσ^siz|z^s=0 ***,several simulation examples are performed for verification of the reliability and efficiency of the proposed semi-analytical methods.

关键词： Film-substrate Imperfect interface Elastic field

Auxetic mechanical metamaterials: from soft to stiff

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International Journal of Extreme Manufacturing 2023年第4期5卷 60-85页

作者： Xiang Li Weitao Peng wenwang wu Jian Xiong Yang Lu School of Sciences Nanjing University of Science and TechnologyNanjing 210094People’s Republic of China School of Naval Architecture Ocean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240People’s Republic of China Center for Composite Materials and Structures Harbin Institute of TechnologyHarbin 150001People’s Republic of China Nano-Manufacturing Laboratory(NML) CityU-Xidian Joint Laboratory of Micro/NanoManufacturingShenzhen Research Institute City University of Hong KongShenzhen 518057People’s Republic of China Department of Mechanical Engineering City University of Hong KongKowloonHong Kong Special Administrative Region of ChinaPeople’s Republic of China Chengdu Research Institute City University of Hong KongChengdu 610200People’s Republic of China Department of Mechanical Engineering The University of Hong KongPokfulamHong Kong Special Administrative Region of ChinaPeople’s Republic of China

Auxetic mechanical metamaterials are artificially architected materials that possess negative Poisson’s ratio,demonstrating transversal contracting deformation under external vertical compression *** physical properties are mainly determined by spatial topological ***,classical auxetic mechanical metamaterials exhibit relatively lower mechanical stiffness,compared to classic stretching dominated ***,in recent years,several novel auxetic mechanical metamaterials with high stiffness have been designed and proposed for energy absorption,load-bearing,and thermal-mechanical coupling *** this paper,mechanical design methods for designing auxetic structures with soft and stiff mechanical behavior are summarized and *** soft auxetic mechanical metamaterials,classic methods,such as using soft basic material,hierarchical design,tensile braided design,and curved ribs,are *** comparison,for stiff auxetic mechanical metamaterials,design schemes,such as hard base material,hierarchical design,composite design,and adding additional load-bearing ribs,are ***-functional applications of soft and stiff auxetic mechanical metamaterials are then *** hope this study could provide some guidelines for designing programmed auxetics with specified mechanical stiffness and deformation abilities according to demand.

关键词： auxetic mechanical metamaterial soft stiff structural design

轻质点阵超结构设计及多功能力学性能调控方法

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力学进展 2022年第3期52卷 673-718页

作者：吴文旺夏热上海交通大学海洋工程国家重点实验室上海200240 上海交通大学船舶海洋与建筑工程学院工程力学系上海200240 武汉大学水力机械过渡过程教育部重点实验室武汉430072

随着先进制造技术、多学科交叉和人工智能科技的飞速发展,高端装备呈现出轻量化、集成化、复合化、功能化、智能化、柔性化和仿生化等发展趋势.传统结构研究存在结构设计和制造相互分离,复杂结构制造效率低、实际制造结构的性能指标和... 详细信息

随着先进制造技术、多学科交叉和人工智能科技的飞速发展,高端装备呈现出轻量化、集成化、复合化、功能化、智能化、柔性化和仿生化等发展趋势.传统结构研究存在结构设计和制造相互分离,复杂结构制造效率低、实际制造结构的性能指标和使用可靠性大幅低于设计理论预测、结构多功能一体化程度不足、经济成本过高等问题.此外,先进工业装备对材料、结构的使用性能、使用环境要求越来越高,亟需开展结构的设计、制造、功能、应用一体化研究,为解决我国先进制造“卡脖子”技术难题提供理论依据和技术支持.轻量化多功能点阵超结构具有轻质高强、抗冲击吸能、减振降噪等性能优势,在航空航天、交通运输、国防、生物医疗、能源、机械等工业领域具有巨大的应用潜力.有鉴于此,受多晶体微结构的多尺度力学设计启发,以“点阵超结构力学设计”为主题,开展点阵超结构的节点、杆件组元,胞元类型、双相结构、梯度结构、多层级结构等典型点阵超结构的几何构筑和力学设计,并阐明多晶体多尺度微观结构启发的点阵超结构力学设计基本原理、多功能力学性能调控方法,以及点阵超结构在不同类型载荷下的结构变形和失效物理机理.

关键词：多功能一体化点阵超结构力学性能多晶体微结构

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集团财务云如何顶层设计?——基于中交集团案例介绍与思考

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管理会计研究 2021年第5期 17-23,86页

作者：吴文往中交集团财务资金部

本文在界定财务云相关概念基础上,以中交集团的财务云建设为背景,对财务云顶层设计背景、目标定位、原则方针、关键控制点、内容框架等进行了探讨,提出财务云设计中的统建分建、体系架构、打通业财边界、系统安全等几大难点问题的解决思... 详细信息

本文在界定财务云相关概念基础上,以中交集团的财务云建设为背景,对财务云顶层设计背景、目标定位、原则方针、关键控制点、内容框架等进行了探讨,提出财务云设计中的统建分建、体系架构、打通业财边界、系统安全等几大难点问题的解决思路,并就财务云顶层规划的具体问题提出了探索性建议。

关键词：财务云财务数字化顶层设计中交案例