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Analyzing the Form-Finding of a Large-Span Transversely Stiffened Suspended Cable System: A Method Considering Construction Processes
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作者 Junyu Chen Yanfei Wang +2 位作者 Ke Chen Shiqing Huang Xiaowen Xu 《World Journal of Engineering and Technology》 2024年第2期229-244,共16页
The precise control of the shape of transversely stiffened suspended cable systems is crucial. However, existing form-finding methods primarily rely on iterative calculations that treat loads as fixed known conditions... The precise control of the shape of transversely stiffened suspended cable systems is crucial. However, existing form-finding methods primarily rely on iterative calculations that treat loads as fixed known conditions. These methods are inefficient and fail to accurately control shape results. In this study, we propose a form-finding method that analyzes the load response of models under different sag and stress levels, taking into account the construction process. To analyze the system, a structural finite element model was established in ANSYS, and geometric nonlinear analysis was conducted using the Newton-Raphson method. The form-finding analysis results demonstrate that the proposed method achieves precise control of shape, with a maximum shape error ranging from 0.33% to 0.98%. Furthermore, the relationships between loads and tension forces are influenced by the deformed shape of the structures, exhibiting significant geometric nonlinear characteristics. Meanwhile, the load response analysis reveals that the stress level of the self-equilibrium state in the transversely stiffened suspended cable system is primarily governed by strength criteria, while shape is predominantly controlled by stiffness criteria. Importantly, by simulating the initial tensioning process as an initial condition, this method solves for a counterweight that satisfies the requirements and achieves a self-equilibrium state with the desired shape. The shape of the self-equilibrium state is precisely controlled by simulating the construction process. Overall, this work presents a new method for analyzing the form-finding process of large-span transversely stiffened suspended cable system, considering the construction process which was often overlooked in previous studies. 展开更多
关键词 Cable Structure Long-Span Structure Form-Finding Analysis Finite Element Simulation Transverse Cable Stiffening System
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Unified simulation of hardening and softening effects for metals up to failure 被引量:1
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作者 Siyu WANG Lin ZHAN +2 位作者 Huifeng XI O.T.BRUHNS Heng XIAO 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2021年第12期1685-1702,共18页
Toward accurately simulating both hardening and softening effects for metals up to failure,a new finite strain elastoplastic J2-flow model is proposed with the yield strength therein as a function of the plastic work ... Toward accurately simulating both hardening and softening effects for metals up to failure,a new finite strain elastoplastic J2-flow model is proposed with the yield strength therein as a function of the plastic work in the explicit form.With no need to identify any adjustable parameters,the uniaxial stress-strain response predicted from this new model is shown to automatically and accurately match any given data from monotonic uniaxial extension tests of bars.As such,the objectives in three respects are achieved for the first time,i.e.,(i)both the hardening and softening effects up to failure can be simulated in the sense of matching test data with no errors,(ii)the usual tedious implicit procedures toward identifying numerous unknown parameters need not be involved and can be totally bypassed,and(iii)the model applicability can be ensured in a broad sense for various metallic materials with markedly different transition effects from hardening to softening.With the new model,the complete response features of stretched bars and twisted tubes up to failure are studied,including the failure effects of bars under monotonic extension and tubes under monotonic torsion and,furthermore,the fatigue failure effects of bars under cyclic loading.The results show accurate agreement with the uniaxial data,and the results for both the shear stress and the normal stress at the finite torsion display realistic hardening-to-softening transition effects for the first time. 展开更多
关键词 metal HARDENING SOFTENING FAILURE NECKING YIELD strength accurate approach
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New finite strain elastoplastic equations for accurately and explicitly simulating pseudoelastic-to-plastic transition effects of shape memory alloys 被引量:1
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作者 Siyu WANG Lin ZHAN +1 位作者 Huifeng XI Heng XIAO 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2020年第10期1583-1596,共14页
A new finite strain elatoplastic J2-flow model with coupling effects of both isotropic and anisotropic hardening is proposed with the co-rotational logarithmic rate.In terms of certain single-variable shape functions ... A new finite strain elatoplastic J2-flow model with coupling effects of both isotropic and anisotropic hardening is proposed with the co-rotational logarithmic rate.In terms of certain single-variable shape functions representing uniaxial loading and unloading curves,explicit multi-axial expressions for the three hardening quantities incorporated in the new model proposed are derived in unified forms for the purpose of automatically and accurately simulating complex pseudoelastic-to-plastic transition effects of shape memory alloys(SMAs)under multiple loading-unloading cycles.Numerical examples show that with only a single parameter of direct physical meaning for each cycle,accurate and explicit simulations may be achieved for extensive data from multiple cycle tests. 展开更多
关键词 shape memory alloy(SMA) finite deformation PSEUDO-ELASTICITY plasticity cyclic loading transition effect elastoplastic equation explicit and accurate approach
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Study on Band Gap Characteristics of Boat-Shaped Phononic Crystal
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作者 Jia Xu Yabing Li Youdi Kuang 《Journal of Applied Mathematics and Physics》 2022年第12期3693-3699,共7页
In this paper, we analyze the two-dimensional Boat-shaped structure based on the finite element method. We calculated its energy band structure and vibration transmission properties and found that the structure has ba... In this paper, we analyze the two-dimensional Boat-shaped structure based on the finite element method. We calculated its energy band structure and vibration transmission properties and found that the structure has band gaps at both high and low frequencies. Compared with common traditional two- dimensional phononic crystals, the boat-shaped phononic crystal has the advantage of larger bandgap design and modulation parameter space due to their structural complexity. In order to obtain better bandgap characteristics, we studied the influence of four key parameters, such as the rod length and the angle between the rods, on the bandgap. The results show that: for low frequency band gaps, the width of the band gap can be effectively changed by changing the size of the angle between the rods while rod length greatly affects the bandgap position;for high band gaps, the length of rods has a large effect on the band gap position. These laws have guiding significance for the bandgap regulation of boat-shaped phononic crystal. 展开更多
关键词 Phononic Crystal Band Gap Boat-Shaped Finite Element Simulation
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Exact simulation for direction-dependent large elastic strain responses of soft fibre-reinforced composites
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作者 Huifeng XI Guicheng ZHAO +2 位作者 OBRUHNS Siyu WANG Heng XIAO 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2023年第9期1497-1510,共14页
An explicit form of the elastic strain-energy function for direction-dependent large elastic strain behaviors of soft fiber-reinforced composites is first presented based upon a decoupled approach for simulating compl... An explicit form of the elastic strain-energy function for direction-dependent large elastic strain behaviors of soft fiber-reinforced composites is first presented based upon a decoupled approach for simulating complex nonlinear coupling effects.From this form,the exact closed-form solutions are then obtained for the uniaxial tension responses in the fiber and cross-fiber directions.With such exact solutions,the issue of simultaneously simulating strongly coupling nonlinear responses in the fiber and cross-fiber directions may be reduced to the issue of separately treating each decoupled uniaxial stress-strain response,thus bypassing usual complexities and uncertainties involved in identifying a large number of strongly coupled adjustable parameters.The numerical examples given are in good agreement with the experimental data for large strain responses. 展开更多
关键词 soft solid fiber-reinforced composite large elastic strain transverse isotropy strain-energy function logarithmic strain decoupling approach
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Experimental and Numerical Studies on Sea Sand Concrete Filled Stainless Steel Tube with Inner FRP Tube Subjected to Axial Compression
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作者 ZENG Lan YU Wen-lan +2 位作者 MO Zi-yong HUANG Shi-qing YUAN Hong 《China Ocean Engineering》 SCIE EI CSCD 2023年第2期272-287,共16页
Since fibre-reinforced polymer(FRP) and stainless steel(SS) offer advantages of corrosion resistance and hybrid confinement, this study proposed a new type of composite column: sea sand concrete(SSC)-filled SS tubular... Since fibre-reinforced polymer(FRP) and stainless steel(SS) offer advantages of corrosion resistance and hybrid confinement, this study proposed a new type of composite column: sea sand concrete(SSC)-filled SS tubular columns with an inner FRP tube(CFSTFs) to help exploit abundant ocean resources in marine engineering. To study compressive behaviours of these novel members, eight CFSTFs and two SSC-filled SS tubular columns(CFSTs)were tested under axial compression. Their axial load-displacement curves, axial load-strain curves in SS or FRP tubes were obtained, and influences of key test parameters(the existence of glass FRP(GFRP) tubes, steel tube shapes, and GFRP tube thicknesses and diameters) were discussed. Further, specimen failure mechanism was analyzed employing the finite element method using ABAQUS software. Test results confirmed the excellent ductility and load-bearing capacity of CFSTFs. The existence of GFRP tubes inside can postpone SS tube buckling, and the content of inner FRP tubes, particularly increasing diameters, was found to improve compressive behaviours. GFRP contents helped develop the second elastic-plastic stage of the load-displacement curves. Furthermore, the bearing capacity of CFSTFs with a circular cross-section was approximately 26% higher than that with a square cross-section, and this difference narrowed with the increase in GFRP ratios. 展开更多
关键词 sea-sand concrete(SSC) confined concrete column fibre-reinforced polymer(FRP)tube stainless steel tube axial compression
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Seismic behavior of large-scale FRP–recycled aggregate concrete–steel columns with shear connectors 被引量:2
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作者 Zeng Lan Li Lijuan +1 位作者 Yang Xianqian Liu Feng 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2019年第4期823-844,共22页
The application of fi ber-reinforced polymer (FRP) composites for the development of high-performance composite structural systems has received signifi cant recent research attention. A composite of FRP–recycled aggr... The application of fi ber-reinforced polymer (FRP) composites for the development of high-performance composite structural systems has received signifi cant recent research attention. A composite of FRP–recycled aggregate concrete (RAC)–steel column (FRSC), consisting of an outer FRP tube, an inner steel tube and annular RAC fi lled between two tubes, is proposed herein to facilitate green disposal of demolished concrete and to improve the ductility of concrete columns for earthquake resistance. To better understand the seismic behavior of FRSCs, quasi-static tests of large-scale basalt FRSCs with shear connectors were conducted. The infl uence of the recycled coarse aggregate (RCA) replacement percentage, shear connectors and axial loading method on the lateral load and deformation capacity, energy dissipation and cumulative damage were analyzed to evaluate the seismic behavior of FRSCs. The test results show that FRSCs have good seismic behavior, which was evidenced by high lateral loads, excellent ductility and energy dissipation capacity, indicating RAC is applicable in FRSCs. Shear connectors can signifi cantly postpone the steel buckling and increase the lateral loads of FRSCs, but weaken the deformation capacity and energy dissipation performance. 展开更多
关键词 recycled AGGREGATE concrete (RAC) fi ber-reinforced polymer (FRP) FRP–RAC–steel COLUMN (FRSC) shear connector seismic behavior
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Propagation Characteristics of Flexural Wave in One-Dimensional Phononic Crystals Based on Lattice Dynamics Model 被引量:2
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作者 Hao Wu Youdi Kuang 《Journal of Applied Mathematics and Physics》 2022年第5期1416-1431,共16页
In this paper, we establish discrete flexural lattice chain models of Bragg and locally resonant phononic crystals by setting mass defect atoms and local resonant elements on the flexural lattice chain. The bandgap ch... In this paper, we establish discrete flexural lattice chain models of Bragg and locally resonant phononic crystals by setting mass defect atoms and local resonant elements on the flexural lattice chain. The bandgap characteristics of flexural wave in phononic crystals are studied by establishing the governing equations of the model. The results from models show that with the change of the mass ratio of defective atoms to normal atoms, the bandgap of the flexural wave produced by Bragg scattering shows a certain rule. When the local resonant bandgap and Bragg scattering bandgap are close to each other, the two bandgaps will be coupled to form a wider flexural wave bandgap. The effect of axial strain on bending wave propagation is only the shift of bandgap position. The effect of material damping on the propagation of a bending wave is only energy dissipation at high frequency. In addition, we use finite element simulation to calculate the bandgap of flexural wave in phononic crystals with mass defects, and the results are consistent with lattice chain model. This shows that lattice chain model can effectively guide the bandgap design of phononic crystals. This comprehensive study may help to elucidate the rule of bandgap generation of flexural wave in one-dimensional phononic crystals. 展开更多
关键词 Phononic Crystals Local Resonance Bragg Scattering DAMPING STRAIN Flexural Wave
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Analysis of Thermo-Magneto-Elastic Nonlinear Dynamic Response of Shallow Conical Shells
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作者 Shende Cen Jiachu Xu 《Engineering(科研)》 2018年第12期837-850,共14页
The dynamic response study on thermo-magneto-elastic behavior of shallow conical shell in a time-dependent magnetic field is investigated, and the dynamic responses of displacement of shallow conical shell under mecha... The dynamic response study on thermo-magneto-elastic behavior of shallow conical shell in a time-dependent magnetic field is investigated, and the dynamic responses of displacement of shallow conical shell under mechanical loads, electromagnetic fields and temperature field coupling are analyzed. Based on Maxwell’s equations, heat conduction equation and nonlinear equations of classical plates and shells, the nonlinear dynamic response governing equations are derived. The electromagnetic field and temperature field equations are solved using variable separating technique, the nonlinear elastic field equations are solved by Galerkin method. The variation of temperature, magnetic field intensity and displacement with time under the coupling effect of the applied magnetic field and the surface uniform load were obtained. The influence of frequency of the applied magnetic field on the displacement wave forms is discussed. 展开更多
关键词 Thermo-Magneto-Elastic SHALLOW Conical SHELL Nonlinear Dynamic RESPONSE GALERKIN Method
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Mechanical Analysis of Interface in Coating Structure under Conical Concave Indenter with FEM
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作者 Shi-Qing Huang Pan-Jun Tang Wen-Hua Zhang 《Journal of Applied Mathematics and Physics》 2022年第5期1509-1524,共16页
The evaluation of mechanical properties of coating structures has always been a very important topic in the fields of mechanics, materials, and machinery. The traditional evaluation methods are easy to produce deviati... The evaluation of mechanical properties of coating structures has always been a very important topic in the fields of mechanics, materials, and machinery. The traditional evaluation methods are easy to produce deviation, because the ratio of coating thickness to substrate thickness is too small. Therefore, accurate analysis and calculation is particularly important. Indentation technology is an important means of coating structure analysis and measurement, the basis of standardized application and analysis of coating structure, and a classical method for accurate analysis and calculation of coating structure. The finite element method is a very good means to analyze and study this kind of problems because of its applicability. Based on the finite element method, this paper analyzes and studies the interface connection form, substrate, and local delamination effects of the indentation behavior of the coating structure under the conical concave indenter. In this paper, the finite element method, which is more convenient for analysis and calculation, is used to analyze the influence of interface connection form, substrate, and local delamination on the coating structure. The results of force displacement, interface normal stress, and interface shear stress are analyzed in detail, and the effects of the three effects on the coating structure are proved. The significance of this study is reflected in: based on the analysis of the three effects of interface connection form, substrate, and local delamination, the mechanical properties of the coating structure are more in-depth, which provides some reference for mechanical engineers to design and test the coating structure. 展开更多
关键词 Coating Structure Finite Element Method Contact Mechanics INTERFACIAL
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Quantitative Simulation Study of Metal Additive Manufacturing by Kinetic Monte Carlo
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作者 Kepeng Ouyang Youdi Kuang 《Journal of Applied Mathematics and Physics》 2022年第5期1587-1601,共15页
Metal additive manufacturing (AM) is a disruptive manufacturing technology that takes into account the needs of complex structural forming and high-performance component forming. At present, the understanding of metal... Metal additive manufacturing (AM) is a disruptive manufacturing technology that takes into account the needs of complex structural forming and high-performance component forming. At present, the understanding of metal additive manufacturing simulation methods is not thorough enough, which restricts the development of metal additive manufacturing. Present work discusses the evolution of KMC method simulation results for simulating metal additive manufacturing at different length ratios and different scanning speeds. The results reveal that as the scanning speed increases, the main grains in the simulation results are transformed from coarse columnar grains to crescent-shaped grains, which are in good agreement with the existing experimental results. Besides, as the ratio of unit physical length to unit simulation length increases, the ratio of unit physical time to unit simulation time gradually decreases. 展开更多
关键词 Additive Manufacturing Kinetic Monte Carlo Simulation Grain Morphology
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Research Progress of the Modification in Sulfur Concrete
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作者 Xuemin You 《Materials Sciences and Applications》 2021年第7期353-361,共9页
Sulfur concrete (SC) is a relatively new type of construction material with advantages of the strong corrosion resistance and quick setting and hardening, which has been applied in construction engineering. SC is brit... Sulfur concrete (SC) is a relatively new type of construction material with advantages of the strong corrosion resistance and quick setting and hardening, which has been applied in construction engineering. SC is brittle with large hardening shrinkage, so it needs to be modified in the process of use. How SC can be modified is a key point of its improvement. In view of the existing research results, the research status of the modification in SC is summarized and concluded in this paper to generate some insights, including the understanding of variations in temperature, effects of molding methods and the addition of fillers and modifiers. 展开更多
关键词 Sulfur Concrete MODIFICATION MOLDING TEMPERATURE FILLER MODIFIER
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Cushioning Performance of a Novel Polyurethane Foam Material Applied in Fragile Packaging 被引量:1
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作者 Huifeng Xi Chunqiu Guo +4 位作者 Jinbiao Yang Xiaogang Wang Bowei Wang Shiqing Huang Zhiwei Wang 《Acta Mechanica Solida Sinica》 SCIE EI CSCD 2024年第3期487-497,共11页
For fragile products,packaging requires cushioning protection to prevent irreversible damage from accidental falls,transportation impacts,and other causes.The new polyurethane foam(PUF)material demonstrates superior c... For fragile products,packaging requires cushioning protection to prevent irreversible damage from accidental falls,transportation impacts,and other causes.The new polyurethane foam(PUF)material demonstrates superior cushioning and vibration isolation performance in practical applications,effectively minimizing damage from vibrations.Drop and vibration experiments were conducted on packages comprising novel PUF,expandable polyethylene,ethylene-vinyl acetate copolymer foam,and bracelets.Results verify that the new PUF material outperforms in cushioning and vibration isolation,as observed from the acceleration response.Furthermore,a random vibration analysis of a packaging unit involving different thicknesses of PUF materials and bracelets reveals the enhanced vibration isolation effect within a specific thickness range.The vibration results of the bracelet’s outer packaging align closely with finite element simulation results,validating the effectiveness of designing and optimizing the outer packaging.Through finite element simulation,deeper understanding and prediction of the bracelet’s vibration response under various conditions is achieved,facilitating optimized packaging design for better protection and vibration damping. 展开更多
关键词 Flexible polyurethane foam Packaging of fragile goods Nonlinear dynamics Vibration frequency Finite element simulation
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Energy Absorption Characteristics of a Novel Asymmetric and Rotatable Re-entrant Honeycomb Structure 被引量:1
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作者 Huifeng Xi Jiachu Xu +1 位作者 Shende Cen Shiqing Huang 《Acta Mechanica Solida Sinica》 SCIE EI CSCD 2021年第4期550-560,共11页
Based on the symmetric re-entrant honeycomb(S-RH)structure with negative Poisson’s ratios,a novel asymmetric and rotatable re-entrant honeycomb(AR-RH)structure was proposed.Both the S-RH structure and AR-RH structure... Based on the symmetric re-entrant honeycomb(S-RH)structure with negative Poisson’s ratios,a novel asymmetric and rotatable re-entrant honeycomb(AR-RH)structure was proposed.Both the S-RH structure and AR-RH structure were produced by the 3D printing technology.Through experimental test and finite element simulation,the deformation mechanism and energy absorption characteristics of the AR-RH structure and the S-RH structure with negative Poisson’s ratios at different impact velocities were compared.The experimental test and finite element simulation results show that the novel AR-RH structure with negative Poisson’s ratios has stronger energy absorption capacity than the S-RH structure,and it has been verified that the rotatability of AR-RH can indeed absorb energy.Furthermore,the degree of asymmetry of the AR-RH structure was discussed. 展开更多
关键词 Asymmetric and rotatable re-entrant honeycomb structure Dynamic compression Energy absorption characteristics Metal 3D printing technology
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Full Characterization of the Work-Hardening Behavior of Metals:An Accurate and Explicit Approach
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作者 Zan Zhou Siyu Wang +2 位作者 Lin Zhan Huifeng Xi Heng Xiao 《Acta Mechanica Solida Sinica》 SCIE EI CSCD 2020年第4期479-486,共8页
A new approach is proposed to characterize the work-hardening behavior of metals based on the stress-strain data from uniaxial extension testing.With this new approach,the yield strength as a function of the plastic w... A new approach is proposed to characterize the work-hardening behavior of metals based on the stress-strain data from uniaxial extension testing.With this new approach,the yield strength as a function of the plastic work can be determined by directly fitting a wellchosen single-variable shape function to any given uniaxial data from the initial yielding up to the strength limit,in an explicit sense with no need to carry out the usual tedious trial-and-error procedures in treating nonlinear elastoplastic rate equations toward identifying numerous unknown parameters.Numerical examples show that the simulation results with the new approach are in accurate agreement with the test data. 展开更多
关键词 METALS Elastoplasticity Finite strain WORK-HARDENING Yield strength Strength limit Explicit characterization
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Lattice Dynamics Models to Predict Transmission Properties of Flexural Waves in One-Dimensional Atom Chains with Defects
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作者 Hao Wu Shihua Huang +2 位作者 Jianyi Luo Laitong He Youdi Kuang 《Acta Mechanica Solida Sinica》 SCIE EI CSCD 2023年第1期105-115,共11页
Flexural waves usually propagate in one-and two-dimensional structures.To further our understanding on their transmission properties from the viewpoint of discrete lattice dynamics,we systematically established analyt... Flexural waves usually propagate in one-and two-dimensional structures.To further our understanding on their transmission properties from the viewpoint of discrete lattice dynamics,we systematically established analytical atom chain models with mass defects and side branches.Both mechanisms of the Bragg scattering and the local resonance corresponding to mass defects and side branches,respectively,are elucidated by means of the present models.The results from the models show that increasing the number of mass defects or side branches decreases the transmission magnitude gradually,and the finite-width phononic bandgap may form due to the periodical arrangement of defects.The interplay between the local resonance and the Bragg scattering gives rise to the narrow phononic bandgap for lattice chains only with periodical side branches.The width of the bandgap strongly depends on the stiffness of side branches.The transmission is insensitive to the tensile strain considered for both kinds of defects,but significantly decreases with an increase in damping or wave frequency.The present work helps further our understanding on the dynamics of flexural waves. 展开更多
关键词 Transmission of flexural waves Lattice dynamics of chains DEFECTS Damping Tensile strains
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Theoretical and Experimental Study on Tension–Torsion Coupling Vibration for Time-Varying Elevator Traction System
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作者 Peng Xu Qifeng Peng +2 位作者 Fusong Jin Jianghong Xue Hong Yuan 《Acta Mechanica Solida Sinica》 SCIE EI CSCD 2023年第6期899-913,共15页
Elevators used in ultra-high buildings are prone to vibrating due to their ultra-long traction ropes,which significantly affects the comfort and safety of high-speed elevators.Therefore,vibration of the elevator has a... Elevators used in ultra-high buildings are prone to vibrating due to their ultra-long traction ropes,which significantly affects the comfort and safety of high-speed elevators.Therefore,vibration of the elevator has always been a topic of research interest.This paper presents a theoretical model for analyzing the tension–torsion coupling vibration of the time-varying elevator traction system.The constitutive relations with the tension–torsion coupling effect of the wire rope are reduced by analyzing the deformation mechanism of the spiral winding wire rope.Based on Hamilton’s principle,the equations of motion and corresponding boundary conditions for the tension–torsion coupling vibration of the elevator traction system are derived.The Galerkin method is employed to account for the influence of nonlinear boundary conditions and to transform the equations of motion into discrete ones with variable coefficients of time,which are solved using the Newmark-βmethod.The accuracy of the proposed model is justified by the good agreement between theoretical predictions and experimental results,following which,the influence of the operation status and structural parameters of the elevator traction system on its vibration performance is discussed in detail. 展开更多
关键词 Elevator traction system Wire rope Tension–torsion vibration TIME-VARYING
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Fluorescent digital image correlation techniques in experimental mechanics 被引量:1
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作者 HU ZhenXing XU TingGe +7 位作者 WANG XueMin XIE ZhiMing LUO HuiYang HE Yong GUO Lei LI YuanPing GAN RongZhu LU HongBing 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2018年第1期21-36,共16页
White light has often been used for surface illumination to acquire images for digital image correlation (DIC) analysis. In recent years, fluorescent imaging technique has been introduced for illumination, surface d... White light has often been used for surface illumination to acquire images for digital image correlation (DIC) analysis. In recent years, fluorescent imaging technique has been introduced for illumination, surface deformation and topography measurements with applications on various materials including biomaterials (biofilms, etc.) at the microscale. Traditional imaging, with the use of white light, encounters technical issues such as specular reflection owing to moisture or smooth shiny surfaces (e.g., metallic or glass surfaces). As an altemative to white light, fluorescent imaging serves as a solution to resolve the issues of specular reflection. Fluorescent DIC techniques, especially the fluorescent stereo DIC, allow 3D surface profilometry and deformation measurements at the microscale and submicron scale. Fluorescent stereo imaging under a microscope utilizes emission wavelengths that are different from illumination wavelengths to ensure clear images on any surface that might give reflections at certain angles when white light is used, allowing accurate metrology and deformation measurement. In addition microscopic fluorescent imaging provides nanoscale resolutions surpassing Abbe's diffraction limit. This paper provides a review of the recent advances in fluorescent DIC. 展开更多
关键词 digital image correlation stereo digital image correlation fluorescent imaging fluorescent stereo microscopy 3D profilometry deformation measurement
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Weak guided wave signal detection using period jump of Duffing system 被引量:1
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作者 ZHANG Weiwei CHENG Mengfei ZHAO Zilong 《Chinese Journal of Acoustics》 CSCD 2022年第1期73-86,共14页
A potential risk in ultrasonic guided wave testing is that weak echo signals from small defects may be submerged in noisy signals,which will cause missed detection.To overcome this shortcoming,a weak guided wave signa... A potential risk in ultrasonic guided wave testing is that weak echo signals from small defects may be submerged in noisy signals,which will cause missed detection.To overcome this shortcoming,a weak guided wave signal detection method based on period jump of the Duffing system is proposed in this paper.The critical state of the system period jump can be obtained by analyzing the bifurcation characteristics of the Duffing system with the variation of the driving force amplitude.A weak ultrasonic guided wave signal with the same frequency as the driving force is added to the driving force.This is equivalent to changing the driving force amplitude,which causes the period state to jump.Consequently,the weak guided wave signals can be identified based on the period jumps.The increase or decrease in the driving force amplitude due to the interference of the guided wave signal depends on the phase difference between the intercepted signal and the periodic driving force.The conditions for increasing and decreasing the driving force amplitude are out of phase with each other.They have an approximate phase difference ofπwithin the same period.Two detection models for small-scale periodic states(SPS)and large-scale periodic states(LPS)are constructed,and the effectiveness of the models in identifying the guided wave signal is verified numerically and experimentally.The anti-noise interference capabilities of the two models are also compared.The results show that the SPS detection model provides unique results and a strong anti-noise ability,and effectively improves the sensitivity of small defect detection using ultrasonic guided waves. 展开更多
关键词 WAVE SYSTEM PERIODIC
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One family of 13315 stable periodic orbits of non-hierarchical unequal-mass triple systems
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作者 XiaoMing Li XiaoChen Li ShiJun Liao 《Science China(Physics,Mechanics & Astronomy)》 SCIE EI CAS CSCD 2021年第1期108-113,共6页
The three-body problem can be traced back to Newton in 1687,but it is still an open question today.Note that only a few periodic orbits of three-body systems were found in 300 years after Newton mentioned this famous ... The three-body problem can be traced back to Newton in 1687,but it is still an open question today.Note that only a few periodic orbits of three-body systems were found in 300 years after Newton mentioned this famous problem.Although triple systems are common in astronomy,practically all observed periodic triple systems are hierarchical(similar to the Sun,Earth and Moon).It has traditionally been believed that non-hierarchical triple systems would be unstable and thus should disintegrate into a stable binary system and a single star,and consequently stable periodic orbits of non-hierarchical triple systems have been expected to be rather scarce.However,we report here one family of 135445 periodic orbits of non-hierarchical triple systems with unequal masses;13315 among them are stable.Compared with the narrow mass range(only 10-5)in which stable"Figure-eight"periodic orbits of three-body systems exist,our newly found stable periodic orbits have fairly large mass region.We find that many of these numerically found stable non-hierarchical periodic orbits have mass ratios close to those of hierarchical triple systems that have been measured with astronomical observations.This implies that these stable periodic orbits of non-hierarchical triple systems with distinctly unequal masses quite possibly can be observed in practice.Our investigation also suggests that there should exist an infinite number of stable periodic orbits of non-hierarchical triple systems with distinctly unequal masses.Note that our approach has general meaning:in a similar way,every known family of periodic orbits of three-body systems with two or three equal masses can be used as a starting point to generate thousands of new periodic orbits of triple systems with distinctly unequal masses. 展开更多
关键词 three-body problem non-hierarchical system periodic orbits
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