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Dynamic characteristics of multi-span spinning beams with elastic constraints under an axial compressive force

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Applied Mathematics and mechanics(English Edition) 2024年第2期45卷 295-310页

作者： Xiaodong GUO Zhu SU Lifeng WANG state key laboratory of mechanics and control for aerospace structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China

A theoretical model for the multi-span spinning beams with elastic constraints under an axial compressive force is *** displacement and bending angle functions are represented through an improved Fourier series,which ensures the continuity of the derivative at the boundary and enhances the *** exact characteristic equations of the multi-span spinning beams with elastic constraints under an axial compressive force are derived by the Lagrange *** efficiency and accuracy of the present method are validated in comparison with the finite element method(FEM)and other *** effects of the boundary spring stiffness,the number of spans,the spinning velocity,and the axial compressive force on the dynamic characteristics of the multi-span spinning beams are *** results show that the present method can freely simulate any boundary constraints without modifying the solution *** elastic range of linear springs is larger than that of torsion springs,and it is not affected by the number of *** an increase in the axial compressive force,the attenuation rate of the natural frequency of a spinning beam with a large number of spans becomes larger,while the attenuation rate with an elastic boundary is lower than that under a classic simply supported boundary.

关键词： multi-span spinning beam elastic constraint improved Fourier series free vibration semi-analytical solution

Vibration of black phosphorus nanotubes via orthotropic cylindrical shell model

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Theoretical & Applied mechanics Letters 2024年第3期14卷 166-173页

作者： Minglei He Lifeng Wang state key laboratory of mechanics and control for aerospace structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China

Black phosphorus nanotubes(BPNTs)may have good properties and potential *** thevibration property of BPNTs is essential for gaining insight into the mechanical behaviour of BPNTs and designingoptimized *** this paper,the mechanical behaviour and vibration property of BPNTs are studied viaorthotropic cylindrical shell model and molecular dynamics(MD)*** vibration frequencies of twochiral BPNTs are analysed *** to the results of MD calculations,it is revealed that thenatural frequencies of two BPNTs with approximately equal sizes are unequal at each order,and that the naturalfrequencies of armchair BPNTs are higher than those of zigzag *** addition,an armchair BPNTs witha stable structure is considered as the object of research,and the vibration frequencies of BPNTs of differentsizes are *** comparing the MD results,it is found that both the isotropic cylindrical shell modeland orthotropic cylindrical shell model can better predict the thermal vibration of the lower order modes of thelonger BPNTs ***,for the vibration of shorter and thinner BPNTs,the prediction of the orthotropiccylindrical shell model is obviously superior to the isotropic shell model,thereby further proving the validity ofthe shell model that considers orthotropic for BPNTs.

关键词： Orthotropic cylindrical shell Molecular dynamics simulation Black phosphorus nanotube Vibration

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

Dynamic response of sandwich panel attached with a double mass-spring-damping system to shallow-buried explosion:Analytical modeling

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Science China(Technological Sciences) 2024年第2期67卷 568-586页

作者： ZHANG DuJiang ZHAO ZhenYu GAO HuiYao LU TianJian state key laboratory of mechanics and control for aerospace structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China MIIT key laboratory of Multifunctional Lightweight Materials and structures(MLMS) Nanjing University of Aeronautics and AstronauticsNanjing 210016China

How to ensure the safety of occupants has become a challenge for protective design of armored vehicles against intensive blast *** this study,for armored vehicles subjected to shallow-buried explosions,an analytical model was established to characterize the dynamic performance of an all-metallic sandwich floorboard attached with a double mass-spring-damping system(mimicking seat and occupant),with the former consisting of a front face,a core and a rear *** validation,numerical simulations with the method of finite elements(FE)were *** agreement between analytical predictions and numerical results was *** analytical model was then employed to quantify the effects of explosive mass,yield stress of material make,configurational parameters of sandwich panel,spring stiffness,and damping coefficient on dynamic response of the sandwich panel and double mass-spring-damping *** increasing explosive mass and decreasing yield stress of material make,the peak displacements of rear face,seat and occupant were all found to *** core relative density was increased,these peak displacements also increased when the ratio of face thickness to core height was relatively *** the ratio of face thickness to core height led to increased peak accelerations of seat and *** peak displacement of rear face was insensitive to the increase of either spring stiffness or damping coefficient,while the peak acceleration of occupant increased with increasing spring *** increasing the damping coefficient between the rear face and seat or that between the seat and occupant or both,the peak acceleration of occupant *** occupant safety duly considered,the proposed analytical model provides useful guidance for designing high-performance protective structures for armored vehicles subjected to intensive blast loadings.

关键词： analytical model shallow-buried explosion sandwich panel occupant safety mass-spring-damping system

Adaptive fault-tolerant control for non-minimum phase hypersonic vehicles based on adaptive dynamic programming

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Chinese Journal of Aeronautics 2024年第3期37卷 290-311页

作者： Le WANG Ruiyun QI Bin JIANG state key laboratory of mechanics and control for aerospace structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China College of Automation Engineering Nanjing University of Aeronautics and AstronauticsNanjing 211106China

In this paper,a novel adaptive Fault-Tolerant control(FTC)strategy is proposed for non-minimum phase Hypersonic Vehicles(HSVs)that are affected by actuator faults and parameter *** strategy is based on the output redefinition method and Adaptive Dynamic Programming(ADP).The intelligent FTC scheme consists of two main parts:a basic fault-tolerant and stable controller and an ADP-based supplementary *** the basic FTC part,an output redefinition approach is designed to make zero-dynamics stable with respect to the new ***,Ideal Internal Dynamic(IID)is obtained using an optimal bounded inversion approach,and a tracking controller is designed for the new output to realize output tracking of the nonminimum phase HSV *** the ADP-based compensation control part,an ActionDependent Heuristic Dynamic Programming(ADHDP)adopting an actor-critic learning structure is utilized to further optimize the tracking performance of the HSV control ***,simulation results are provided to verify the effectiveness and efficiency of the proposed FTC algorithm.

关键词： Hypersonic vehicle Fault-tolerant control Non-minimum phase system Adaptive control Nonlinear control Adaptive dynamic programming

Theoretical study on magnetocaloric effect and its electric-field regulation in CrI_(3)/metal heterostructure

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Science China(Physics,mechanics & Astronomy) 2024年第2期67卷 134-141页

作者： Weiwei He Ziming Tang Qihua Gong Min Yi Wanlin Guo state key laboratory of mechanics and control for aerospace structures Key Laboratory for Intelligent Nano Materials and Devices of Ministry of EducationInstitute for Frontier ScienceNanjing University of Aeronautics and AstronauticsNanjing 210016China MIIT key laboratory of aerospace Information Materials and Physics College of PhysicsNanjing University of Aeronautics and AstronauticsNanjing 211106China

The extraordinary properties of a heterostructure by stacking atom-thick van der Waals(vdW)magnets have been extensively ***,the magnetocaloric effect(MCE)of heterostructures that are based on monolayer magnets remains to be ***,we deliberate MCE of vd W heterostructure composed of a monolayer CrI_(3)and metal atomic layers(Ag,Hf,Au,and Pb).It is revealed that heterostructure engineering by introducing metal substrate can improve MCE of CrI_(3),particularly boosting relative cooling power to 471.72μJ m^(-2)and adiabatic temperature change to 2.1 K at 5 T for CrI_(3)/*** improved MCE is ascribed to the enhancement of magnetic moment and intralayer exchange coupling in CrI_(3)due to the CrI_(3)/metal heterointerface induced charge *** field is further found to tune MCE of CrI_(3)in heterostructures and could shift the peak temperature by around 10 K in CrI_(3)/Hf,thus manipulating the working temperature window of *** theoretical results could enrich the research on low-dimensional magnetocaloric materials.

关键词： magnetocaloric effect heterostructure metal substrate

An Aerial–Wall Robotic Insect That Can Land, Climb, and Take Off from Vertical Surfaces

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Research 2024年第1期2023卷 149-163页

作者： Qian Li Haoze Li Huan Shen Yangguang Yu Haoran He Xincheng Feng Yi Sun Zhiyuan Mao Guangming Chen Zongjun Tian Lida Shen Xiangming Zheng Aihong Ji College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjingChina College of aerospace Engineering Nanjing University of Aeronautics and AstronauticsNanjingChina state key laboratory of mechanics and control for aerospace structures Nanjing University of Aeronautics and AstronauticsNanjingChina

Insects that can perform flapping-wing flight,climb on a wall,and switch smoothly between the 2 locomotion regimes provide us with excellent biomimetic ***,very few biomimetic robots can perform complex locomotion tasks that combine the 2 abilities of climbing and ***,we describe an aerial–wall amphibious robot that is self-contained for flying and climbing,and that can seamlessly move between the air and *** adopts a flapping/rotor hybrid power layout,which realizes not only efficient and controllable flight in the air but also attachment to,and climbing on,the vertical wall through a synergistic combination of the aerodynamic negative pressure adsorption of the rotor power and a climbing mechanism with bionic adhesion *** the basis of the attachment mechanism of insect foot pads,the prepared biomimetic adhesive materials of the robot can be applied to various types of wall surfaces to achieve stable *** longitudinal axis layout design of the rotor dynamics and control strategy realize a unique cross-domain movement during the flying–climbing transition,which has important implications in understanding the takeoff and landing of ***,it enables the robot to cross the air–wall boundary in 0.4 s(landing),and cross the wall–air boundary in 0.7 s(taking off).The aerial–wall amphibious robot expands the working space of traditional flying and climbing robots,which can pave the way for future robots that can perform autonomous visual monitoring,human search and rescue,and tracking tasks in complex air–wall environments.

关键词： robot smoothly Vertical

Closed-Form Solution for a Circular Nanohole with Surface Effects Under Uniform Heat Flux

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Acta Mechanica Solida Sinica 2024年第1期37卷 43-52页

作者： Jieyao Tang Jieyan Zhao Haibing Yang Cunfa Gao state key laboratory of mechanics and control for aerospace structures Nanjing University of Aeronautics and AstronauticsNanjing 210016China School of Civil Engineering and Transportation South China University of TechnologyGuangzhou 510641China College of mechanics and Materials Hohai UniversityNanjing 211100China

This paper investigates the steady-state thermoelastic problem of a circular nanohole embedded in an infinitely large elastic plane subjected to a uniform far-field heat flux.A lowly conductive surface model is used to account for the effects of surface phonon scattering,while the complete Gurtin–Murdoch model is utilized to characterize the effects of surface tension and surface *** closed-form solution to the temperature and stress field surrounding the hole is derived in the context of complex variable *** numerical examples are presented to analyze the influence of surface effects on thermal stress *** is shown that surface effects induce notable increases in normal and shear stresses around the ***,all three stress components(hoop,normal,and shear)in the vicinity of the hole exhibit substantial augmentation with increasing surface tension and surface *** particular,it is found that the presence of surface effects amplifies the variation in stress gradients and intensifies stress concentration around the hole.

关键词： Circular nanohole Surface effect Thermal stress Heat flux

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

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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