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Isogeometric Analysis for the Arbitrary AFG Microbeam with Two-Phase Nonlocal Stress-Driven Model

Acta Mechanica Solida Sinica 2024年第2期37卷 341-360页

作者： Pei-Liang Bian Zhaowei Liu Hai Qing Tiantang Yu Department of Engineering Mechanics Hohai UniversityNanjing211100China State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing210016China

Scale effects play critical roles in the mechanical responses of *** isogeometric analysis was developed here to investigate the mechanical responses of an axially functionally graded *** Euler–Bernoulli beam model was utilized,and size effects in the structure were modeled with a stress-driven two-phase local/nonlocal integral *** governing equation of microstructures was given in an equivalent differential form with two additional constitutive boundary *** framework was verified and utilized to analyze the microbeam’s static and dynamic mechanical *** present work showed great potential for modeling various types of functionally graded microstructures.

关键词： Isogeometric analysis Size effect Functionally graded material Nonlocal theory Euler-Bernoulli beam

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Initiation of dendritic NMDA spikes co-regulated via distance-dependent and dynamic distribution of the spine number and morphology in neuron dendrites

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Science China(Technological Sciences) 2023年第2期66卷 429-438页

作者： CAO YuWei SHEN Chun QIU Hu GUO WanLin State Key Laboratory of Tribology Department of Mechanical EngineeringTsinghua UniversityBeijing 100084China State Key Laboratory of Mechanics and Control of Mechanical Structure and Key Laboratory for Intelligent Nano Materials and Devices of the Ministry of Education Institute for Frontier Science and Institute of NanoscienceNanjing University of Aeronautics and AstronauticsNanjing 210016China

Dendritic spines are small membranous protrusions that receive synaptic inputs from other neurons,enabling the initiation of dendritic N-methyl-D-aspartic(NMDA)spikes and somatic action *** learning and memory processes,both the number of spines on a dendrite and the morphology of individual spines are constantly *** individual influence of spine number and morphology on dendritic NMDA spikes has already been revealed,but the functional significance of the coregulation of spine number and morphology on NMDA spikes remains ***,we systematically investigated the initiation of local dendritic NMDA spikes by the dynamic distributions of the spine number and morphology on single dendrites in reconstructed neuron *** from the traditional cognition,we found the threshold number of spines required to generate local dendrite NMDA spikes on distal dendrites is fewer than that on proximal ones,because the thinner distal dendrites own higher *** for the spine morphology,the presence of moreα-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid(AMPA)receptors on the spine leads to larger NMDA spikes rather than an increase in the spine dimension ***,we first suggested that a single dendrite containing spines with gradually increasing head diameters away from the soma could generate larger NMDA spikes than that irrational distribution of spine morphology containing spines with decreasing head diameters,which can be compensated by the increasing spine ***,the distance-dependent distribution of spine number and morphology co-regulate the intension of dendritic NMDA *** findings about the threshold for NMDA spikes provide novel insights into the role of the irrational dynamic distribution of the spine number and morphology in senescence and disease processes such as Alzheimer’s disease,schizophrenia,and Parkinson’s disease,which causes abnormal neuron firing.

关键词： dendritic spine spine number spine morphology NMDA spikes memory neurological diseases

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Peridynamic Study on Fracture Mode and Crack Propagation Path of a Plate with Multiple Cracks Subjected to Uniaxial Tension

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Computer Modeling in Engineering & Sciences 2023年第12期137卷 2593-2620页

作者： Zeyuan Zhou Ming Yu Xinfeng Wang Zaixing Huang State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing210016Chin

How to simulate fracture mode and crack propagation path in a plate with multiple cracks is an attractive but difficult issue in fracture *** is a recently developed nonlocal continuum formulation that can spontaneously predict the crack nucleation,branch and propagation in materials and structures through a meshfree discrete *** this paper,the peridynamic motion equation with boundary traction is improved by simplifying the boundary transfer *** calculate the critical cracking load and the fracture angles of the plate with multiple cracks under uniaxial *** results are consistent with those predicted by classical fracture *** fracture mode and crack propagation path are also *** calculation shows that the brittle fracture process of the plate with multiple cracks can be conveniently and correctly simulated by the peridynamic motion equation with boundary conditions.

关键词： Peridynamics multiple cracks brittle fracture crack propagation

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Epitaxial growth of borophene on graphene surface towards efficient and broadband photodetector

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Nano Research 2024年第4期17卷 3053-3060页

作者： Zenghui Wu Chen Shifan Zitong Wu Yi Liu Wei Shao Xinchao Liang Chuang Hou Guoan Tai The State Key Laboratory of Mechanics and Control of Mechanical Structures and Laboratory of Intelligent Nano Materials and Devices of Ministry of Education College of Aerospace EngineeringNanjing University of Aeronautics and AstronauticsNanjing 210016China

In-situ integration of multiple materials with well-defined interfaces as heterostructures is of great interest due to their unique properties and potential for new device *** of its polymorphism and diverse bonding geometries,borophene is a promising candidate for two-dimensional heterostructures,but suitable synthesis conditions have limited its potential *** this end,we demonstrate the vertical borophene and graphene heterostructures which form by epitaxial growth of borophene onto multilayer graphene on Cu substrates via chemical vapor deposition,where hydrogen and NaBH_(4) are respectively used as the carrier gas and the boron *** lattice structure of the as-synthesized borophene well coincides with the predictedα′-boron *** borophene-based photodetector shows an excellent broadband photoresponse from the ultraviolet(255 nm)to the infrared(940 nm)wavelengths,with enhanced responsivity compared to pristine borophene or graphene *** work informs emerging efforts to integrate borophene into nanoelectronic applications for both fundamental investigations and technological applications.

关键词： borophene graphene heterostructure photodetector two-dimensional materials

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Free vibration of functionally graded sandwich plates in thermal environments

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International Journal of mechanical System Dynamics 2023年第1期3卷 39-47页

作者： Dongdong Li Zongbai Deng Guoping Chen State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjingChina

This paper presents an analytical solution for the free vibration of functionally graded material(FGM)sandwich plates in a thermal *** equivalentsingle‐layer(ESL)plate theory with four variables is used to obtain the *** types of sandwich plates are examined in this study:one with FGM face sheets and a homogeneous core and the other with an FGM core and homogeneous face *** governing equations of motion are derived based on Hamilton's principle and then solved using the Navier *** results of natural frequencies of simply supported FGM sandwich plates are compared with the available solutions in the *** effects of volume fraction distribution,geometrical parameters,and temperature increments on the free vibration characteristics are discussed in detail.

关键词： functionally graded material sandwich plate equivalent‐single‐layer theory free vibration

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Ultralow friction of ion-containing water nanodroplets

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Nano Research 2023年第1期16卷 1792-1797页

作者： Jie Tan Yufeng Guo Wanlin Guo State Key Laboratory of Mechanics and Control of Mechanical Structures MOE Key Laboratory for Intelligent Nano Materials and DevicesCollege of Aerospace EngineeringNanjing University of Aeronautics and AstronauticsNanjing 210016China

We reveal the ultralow friction or superlubricity of water nanodroplets containing cations and anions on graphene substrates at high ion concentration by molecular dynamics *** the ion concentration is higher than 7 wt.%and the nanodroplet diameter is larger than 10 nm,the friction coefficients of water nanodroplets are lower than 10−2,and can decrease to the order of 10−3 with increasing the ion concentration *** a certain ion concentration,the optimal nanodroplet diameter of 17–20 nm exists at which the friction coefficient is the *** ultralow friction behaviors of water nanodroplets containing cations and anions are mainly attributed to the opposite variation trends between the interfacial adhesion energy and surface energy of water nanodroplet with ion concentration,and the interfacial hydrophobicity sustained by high ion *** results unveil the essential role of ions in achieving the superlubricity of water nanodroplets.

关键词： water nanodroplet ion ultralow friction molecular dynamics

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Ion-Induced Friction Reduction in Water Nanoflow over Graphene

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Acta Mechanica Solida Sinica 2023年第2期36卷 214-220页

作者： Yue Wang Yufeng Guo Wanlin Guo State Key Laboratory of Mechanics and Control of Mechanical Structures MOE Key Laboratory for Intelligent Nano Materials and DevicesCollege of Aerospace EngineeringNanjing University of Aeronautics and AstronauticsNanjing 210016China

Our extensive nonequilibrium and equilibrium molecular dynamics simulations reveal the ion-induced interfacial friction reduction of NaCl-containing water nanoflow over *** under a normal pressure,with the increase in ion concentration,the friction coefficients of water nanoflow at the water/graphene interfaces decrease,and the slip lengths and shear viscosities of water nanoflow *** interfacial friction reduction with the increase in ion concentration is mainly attributed to the decrease in interfacial hydrated ions and the weaker binding of water molecules with graphene at a higher ion *** presence of ions changes the hydrogen bond networks and structural configuration of water molecules close to the underlying graphene sheets and plays a key role in reducing the interfacial friction between water nanoflow and graphene.

关键词： Water nanoflow Ion Friction reduction Molecular dynamics

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Excitation-assisted pseudo-ferroelectric effect in ultrathin graphene/phosphorene heterostructure

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Nano Research 2023年第11期16卷 12587-12593页

作者： Huan Lu Wanlin Guo State Key Laboratory of Mechanics and Control of Mechanical Structures Key Laboratory for Intelligent Nano Materials and Devices of Ministry of Educationand Institute for Frontier ScienceNanjing University of Aeronautics and AstronauticsNanjing 210016China

Pseudo-ferroelectric transistors have attracted particular interest owing to their applications in the non-volatile memories and neuromorphic circuits;however,it remains to be explored in the limit of few-layer *** we reveal a pseudo-ferroelectric phenomenon in the ultrathin graphene/black phosphorene(G/BP)heterostructure by first-principles *** forward an excitation-assisted mechanism,the ferroelectric-like hysteresis loop can be explained by a combined effect of the external electric fields dependent bipolarity and anisotropy in the G/BP *** the build-in electric field,the bipolar behavior results in the multistate effect of the G/BP heterostructure when modulating the applied electric *** anisotropic hybridization caused by the susceptible Dirac electrons in graphene and the large in-plane anisotropy in BP provides the interfacial states,which trap excitations and stabilize the *** pseudo-ferroelectric behavior should be useful for interpreting transport experiments in gated G/BP devices and exploring its applications in memories or synaptic devices.

关键词： pseudo-ferroelectric effect charge trapping graphene/phosphorene heterostructure first-principles calculations

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Design and Theoretical Research on Aerial-Aquatic Vehicles:A Review

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Journal of Bionic Engineering 2023年第6期20卷 2512-2541页

作者： Yi Sun Xuefei Liu Kai Cao Huan Shen Qian Li Guangming Chen Jiajun Xu Aihong Ji Lab of Locomotion Bioinspiration and Intelligent Robots College of Mechanical and Electrical EngineeringState Key Laboratory of Mechanics and Control for Aerospace StructuresNanjing University of Aeronautics and Astronautics29 Yudao StreetNanjing210016China State Key Laboratory of Mechanics and Control for Aerospace Structures Nanjing University of Aeronautics and AstronauticsNanjing210016China

With the rapid development of unmanned aerial and underwater vehicles,various tasks,such as biodiversity monitoring,surveying,and mapping,as well as,search and rescue can now be completed in a single medium,either underwater or in the *** systematically examining the water–air cross-medium locomotion of organisms,there has been growing interest in the development of aerial-aquatic *** goal of this review is to provide a detailed outline of the design and cross-medium theoretical research of the existing aerial-aquatic vehicles based on the research on the organisms capable of transiting between water and *** these designs and theoretical frameworks have been validated in many aerial-aquatic vehicles,there are still many problems that need to be addressed,such as inflexible underwater motion and unstable medium *** a result,supplementation of the existing cross-medium biomimetic research,vehicle design,power selection,and cross-medium theory is urgently required to optimize the key technologies in ***,by summarizing the existing designs and theoretical approaches on aerial-aquatic vehicles,including biomimetic research on water–air cross-medium locomotion in nature,different power selections,and cross-medium theoretical research,the relative problems and development trends on aerial-aquatic vehicles were thoroughly explored,providing significant help for the subsequent research process.

关键词： Aerial-aquatic vehicle Cross-medium motion Power selection control theory Biomimetic

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Geometry independent C^(*)-T_(z) dominance of three-dimensional quasistatic growing crack-tip fields in creeping solids

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Science China(Physics,mechanics & Astronomy) 2022年第1期65卷 22-32页

作者： PengFei Cui WanLin Guo State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China

In creeping solids,plane stress and plane strain solutions for asymptotic singular crack-tip fields have been first put forward by Riedel and Rice with C^(*)as the dominating parameter and developed by Xiang and Guo into three-dimensional solution(3D)for stationary cracks under the domination of C^(*)with the constraint factor ***,how to characterize the 3D crack-tip fields under creep damage-induced quasistatic growing conditions remains *** this study,we reveal that,for 3D quasistatic growing cracks,the leading singular solution can effectively characterize the crack-tip stress distributions with relative errors less than 10.8%for relative creep time up to 0.8 in various specimens with finite *** a given relative time,Tz distributions can be unified by the equivalent thickness concept,*** results show that C^(*)-T_(z) can effectively quantify both the load and constraint effects on the crack-tip *** geometry independent dominance can considerably simplify the treatments of load and constraint effects,thereby promoting the application of fracture mechanics in high-temperature damage tolerance designs.

关键词： quasistatic growing crack-tip fields C^(*)-T_(z)solution geometry independence constraints creep damage

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