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Noether Symmetry and Conserved Quantities of Fractional Birkhoffian System in Terms of Herglotz Variational Problem 认领 引用 被引量：3
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作者 Xue Tian Yi Zhang 《Communications in Theoretical Physics》 SCIE CAS CSCD 2018年第9期280-288,共9页
The aim of this paper is to study the Herglotz variational principle of the fractional Birkhoffian system and its Noether symmetry and conserved quantities. First, the fractional Pfaff-Herglotz action and the fraction... The aim of this paper is to study the Herglotz variational principle of the fractional Birkhoffian system and its Noether symmetry and conserved quantities. First, the fractional Pfaff-Herglotz action and the fractional PfaffHerglotz principle are presented. Second, based on different definitions of fractional derivatives, four kinds of fractional Birkhoff’s equations in terms of the Herglotz variational principle are established. Further, the definition and criterion of Noether symmetry of the fractional Birkhoffian system in terms of the Herglotz variational problem are given. According to the relationship between the symmetry and the conserved quantities, the Noether’s theorems within four different fractional derivatives are derived, which can reduce to the Noether’s theorem of the Birkhoffian system in terms of the Herglotz variational principle under the classical conditions. As applications of the Noether’s t heorems of the fractional Birkhoffian system in terms of the Herglotz variational principle, an example is given at the end of this paper. 展开更多
关键词 fractional Birkhoffian system Herglotz variational problem Noether symmetry conserved quantity
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Theoretical and Experimental Analyses of Poisson Ratios for Plain-Woven Fabrics 认领 引用 被引量：2
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作者 陈建稳 陈务军 《Journal of Donghua University(English Edition)》 EI CAS 2015年第3期351-356,共6页
A theoretical model with extensible yarns for plain-woven fabrics is developed to determine the calculation of Poisson ratios.The stress ratio( warp: weft),as one of parameters corresponding to Poisson ratio variation... A theoretical model with extensible yarns for plain-woven fabrics is developed to determine the calculation of Poisson ratios.The stress ratio( warp: weft),as one of parameters corresponding to Poisson ratio variations, is introduced to complement the theoretical model. To evaluate the reliability of the theoretical analysis,a series of biaxial tensile tests of a plain-woven fabric with nine stress ratios are conducted carefully,and the theoretical results are compared with the experimentally measured values. The effects of other influencing factors, including geometric and mechanical parameters of yarns,on Poisson ratios are analyzed thoroughly.This solution method could be applied without difficulty to estimations of Poisson ratios and realistic designs for plain-woven fabrics. 展开更多
关键词 Poisson ratios plain-woven fabrics mechanical properties stress ratios tensile testing
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Combining Cubic Spline Interpolation and Fast Fourier Transform to Extend Measuring Range of Reflectometry 认领 引用
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作者 Ju Cheng Jian Lu +7 位作者 Hong-Chao Zhang Feng Lei Maryam Sardar Xin-Tian Bian Fen Zuo Zhong-Hua Shen Xiao-Wu Ni Jin Shi 《Chinese Physics Letters》 SCIE EI CAS CSCD 2018年第5期20-24,共5页
The reflectometry is a common method used to measure the thickness of thin films. Using a conventional method,its measurable range is limited due to the low resolution of the current spectrometer embedded in the refle... The reflectometry is a common method used to measure the thickness of thin films. Using a conventional method,its measurable range is limited due to the low resolution of the current spectrometer embedded in the reflectometer.We present a simple method, using cubic spline interpolation to resample the spectrum with a high resolution,to extend the measurable transparent film thickness. A large measuring range up to 385 m in optical thickness is achieved with the commonly used system. The numerical calculation and experimental results demonstrate that using the FFT method combined with cubic spline interpolation resampling in reflectrometry, a simple,easy-to-operate, economic measuring system can be achieved with high measuring accuracy and replicability. 展开更多
关键词 Figure FFT Combining Cubic Spline Interpolation and Fast Fourier Transform to Extend Measuring Range of Reflectometry
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Ultrasensitive Mechanical Sensor Using Tunable Ordered Array of Metallic and Insulating States in Vanadium Dioxide 认领 引用
4
作者 马泽成 闫胜楠 +12 位作者 陈繁强 戴玉頔 刘增霖 徐康 徐涛 童湛钦 陈墨雨 王利铮 王鹏飞 孙立涛 程斌 梁世军 缪峰 《Chinese Physics Letters》 SCIE EI CAS CSCD 2024年第7期74-86,共13页
Detecting tiny deformations or vibrations, particularly those associated with strains below 1%, is essential in various technological applications. Traditional intrinsic materials, including metals and semiconductors,... Detecting tiny deformations or vibrations, particularly those associated with strains below 1%, is essential in various technological applications. Traditional intrinsic materials, including metals and semiconductors, face challenges in simultaneously achieving initial metallic state and strain-induced insulating state, hindering the development of highly sensitive mechanical sensors. Here we report an ultrasensitive mechanical sensor based on a strain-induced tunable ordered array of metallic and insulating states in the single-crystal bronze-phase vanadium dioxide [VO2(B)] quantum material. It is shown that the initial metallic state in the VO2(B) flake can be tuned to the insulating state by applying a weak uniaxial tensile strain. Such a unique property gives rise to a record-high gauge factor of above 607970, surpassing previous values by an order of magnitude, with excellent linearity and mechanical resilience as well as durability. As a proof-of-concept application, we use our proposed mechanical sensor to demonstrate precise sensing of the micro piece, gentle airflows and water droplets. We attribute the superior performance of the sensor to the strain-induced continuous metal-insulator transition in the single-crystal VO2(B) flake, evidenced by experimental and simulation results. Our findings highlight the potential of exploiting correlated quantum materials for next-generation ultrasensitive flexible mechanical sensors, addressing critical limitations in traditional materials. 展开更多
关键词 metallic durability hinder
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Explosion resistance performance of reinforced concrete box girder coated with polyurea:Model test and numerical simulation 认领 引用 被引量：5
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作者 Guangpan Zhou Rong Wang +2 位作者 Mingyang Wang Jianguo Ding Yuye Zhang 《Defence Technology（防务技术）》 SCIE EI CAS CSCD 2024年第3期1-18,共18页
To study the anti-explosion protection effect of polyurea coating on reinforced concrete box girder,two segmental girder specimens were made at a scale of 1:3,numbered as G(without polyurea coating)and PCG(with polyur... To study the anti-explosion protection effect of polyurea coating on reinforced concrete box girder,two segmental girder specimens were made at a scale of 1:3,numbered as G(without polyurea coating)and PCG(with polyurea coating).The failure characteristics and dynamic responses of the specimens were compared through conducting explosion tests.The reliability of the numerical simulation using LS-DYNA software was verified by the test results.The effects of different scaled distances,reinforcement ratios,concrete strengths,coating thicknesses and ranges of polyurea were studied.The results show that the polyurea coating can effectively enhance the anti-explosion performance of the girder.The top plate of middle chamber in specimen G forms an elliptical penetrating hole,while that in specimen PCG only shows a very slight local dent.The peak vertical displacement and residual displacement of PCG decrease by 74.8% and 73.7%,respectively,compared with those of specimen G.For the TNT explosion with small equivalent,the polyurea coating has a more significant protective effect on reducing the size of fracture.With the increase of TNT equivalent,the protective effect of polyurea on reducing girder displacement becomes more significant.The optimal reinforcement ratio,concrete strength,thickness and range of polyurea coating were also drawn. 展开更多
关键词 Explosive load Explosion resistance performance Model test Polyurea Concrete box girder Numerical simulation
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Nonlinear coupling modeling and dynamics analysis of rotating flexible beams with stretching deformation effect 认领 引用 被引量：4
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作者 Xiaokang DU Yuanzhao CHEN +3 位作者 Jing ZHANG Xian GUO Liang LI Dingguo ZHANG 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2023年第1期125-140,共16页
Dynamic coupling modeling and analysis of rotating beams based on the nonlinear Green-Lagrangian strain are introduced in this work.With the reservation of the axial nonlinear strain,there are more coupling terms for ... Dynamic coupling modeling and analysis of rotating beams based on the nonlinear Green-Lagrangian strain are introduced in this work.With the reservation of the axial nonlinear strain,there are more coupling terms for axial and transverse deformations.The discretized dynamic governing equations are obtained by using the finite element method and Lagrange’s equations of the second kind.Time responses are conducted to compare the proposed model with other previous models.The stretching deformation due to rotating motion is observed and calculated by special formulations under dynamic equilibrium.The stretching deformation and the change of the associated equilibrium position are taken into account to analyze the free vibration and frequency response of the rotating beams.Analytical and numerical comparisons show that the proposed model can provide reliable results,while the previous models may lead to imprecise results,especially in high-speed conditions. 展开更多
关键词 rotating beam finite element method stiffening effect stretching deformation dynamic equilibrium
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Dynamic modeling of ultra-precision fly cutting machine tool and the effect of ambient vibration on its tool tip response 认领 引用 被引量：4
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作者 Jianguo Ding Yu Chang +4 位作者 Peng Chen Hui Zhuang Yuanyuan Ding Hanjing Lu Yiheng Chen 《International Journal of Extreme Manufacturing》 SCIE EI CAS 2020年第2期120-136,共17页
The dynamic performances of an ultra-precision fly cutting machine tool(UFCMT)has a dramatic impact on the quality of ultra-precision machining.In this study,the dynamic model of an UFCMT was established based on the ... The dynamic performances of an ultra-precision fly cutting machine tool(UFCMT)has a dramatic impact on the quality of ultra-precision machining.In this study,the dynamic model of an UFCMT was established based on the transfer matrix method for multibody systems.In particular,the large-span scale flow field mesh model was created;and the variation in linear and angular stiffness of journal and thrust bearings with respect to film thickness was investigated by adopting the dynamic mesh technique.The dynamic model was proven to be valid by comparing the dynamic characteristics of the machine tool obtained by numerical simulation with the experimental results.In addition,the power spectrum density estimation method was adopted to simulate the statistical ambient vibration excitation by processing the ambient vibration signal measured over a long period of time.Applying it to the dynamic model,the dynamic response of the tool tip under ambient vibration was investigated.The results elucidated that the tool tip response was significantly affected by ambient vibration,and the isolation foundation had a good effect on vibration isolation. 展开更多
关键词 ultra-precision fly cutting machine tool transfer matrix method for multibody systems dynamic response of tool tip power spectrum density estimation method ambient vibration
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Experimental and numerical investigation on penetration of clay masonry by small high-speed projectile 认领 引用 被引量：3
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作者 Cheng-zong Wang Ai-jun Chen +3 位作者 Zi-qing Li Chao-an Gong Shu Wang Wen-min Yan 《Defence Technology（防务技术）》 SCIE EI CAS CSCD 2021年第4期1514-1530,共17页
This study investigates a kind of masonry consisting of clay-fired brick(fc=10 MPa;r=1:38 g/cm3)and mortar(fc=10 MPa;r=1:8 g/cm3).Clay-fired brick masonry connotes a traditional construction material of ol... This study investigates a kind of masonry consisting of clay-fired brick(fc=10 MPa;r=1:38 g/cm3)and mortar(fc=10 MPa;r=1:8 g/cm3).Clay-fired brick masonry connotes a traditional construction material of old architecture and public buildings.We carried out penetration experiments in which four clay-fired brick walls employing two different patterns were subjected to impact from small high-speed projectile,i.e.12.7 mm armor-piercing explosive incendiary projectile and material tests in which the static and dynamic compressive strengths of clay-fired brick and mortar were determined by quasi-static and SHPB(Split Hopkinson Pressure Bar)tests.The experimental data include hit and exit velocities,damage configuration of clay brick masonry and mechanical properties of material at low and high strain rates,though which influence of thickness and bonding patterns of wall on kinetic loss of bullet,the damage patterns of masonry observed experimentally and dynamic increase of material strengths are analyzed.To keep minimum boundary inconsistency with reality,full 3D detailed finite element model consisting of two different material is established.Sharing common nodes and employing automatic tiebreak contact are combined to reduce computational time usage of large-scale model.For description of clay-fired brick and mortar RiedeleHiermaiereThoma(RHT)material model is employed.Material parameter set is derived based on experimental data,available literature and engineering assumptions.The numerical simulations study the mesh resolution dependency of material model,reproduce the crucial phenomena of masonry in experiment acceptably and offer more time-resolved insight into motion of bullet in the process of penetration.The feasibility of means of constructing finite element model and applying RHT model to the masonry herein and analogous constructions is explored through numerical investigation. 展开更多
关键词 Clay-fired brick Penetration of masonry RHT model Impact High strain rate
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Thermomechanical response of aluminum alloys under the combined action of tensile loading and laser irradiations 认领 引用 被引量：3
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作者 Mohsan Jelani Zewen Li +1 位作者 Zhonghua Shen Maryam Sardar 《Chinese Physics B》 SCIE EI CAS CSCD 2018年第3期469-480,共12页
This study reports the investigation of the thermomechanical behavior of aluminum alloys(AI-1060,A1-6061,and A1-7075)under the combined action of tensile loading and laser irradiations.The continuous wave ytterbium fi... This study reports the investigation of the thermomechanical behavior of aluminum alloys(AI-1060,A1-6061,and A1-7075)under the combined action of tensile loading and laser irradiations.The continuous wave ytterbium fiber laser(wavelength 1080 nm)was employed as the irradiation source,while tensile loading was provided by the tensile testing machine.The effects of various pre-loading and laser power densities on the failure time,temperature distribution,and the deformation behavior of aluminum alloys are analyzed.The experimental results represent the significant reduction in failure time for higher laser power densities and for high preloading values,which implies that preloading may contribute a significant role in the failure of the material at elevated temperature.Fracture on a microscopic scale was predominantly ductile comprising micro-void nucleation,growth,and coalescence.The AI-1060 specimens behaved plastically to some extent,while A1-6061 and A1-7075 specimens experienced catastrophic failure.The reason and characterization of ma-terial failure by tensile and laser loading are explored in detail.A comparative behavior of under-tested materials is also investigated.This work suggests that studies considering only combined loading are not enough to fully understand the mechanical behavior of under-tested materials.For complete characterization,one should consider the effect of heating as well as loading rate and the corresponding involved processes with the help of thermomechanical coupling and the thermal elastic-plastic theory. 展开更多
关键词 aluminum alloys fiber laser tensile loading thermomechanical effects failure evolution
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Enhancement of Light Absorption in Thin Film Silicon Solar Cells with Metallic Grating and One-Dimensional Photonic Crystals 认领 引用 被引量：8
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作者 ZHENG Gai-Ge XIAN Feng-Lin LI Xiang-Yin 《Chinese Physics Letters》 SCIE EI CAS CSCD 2011年第5期151-154,共4页
We design an effective light trapping scheme through engineering metallic gratings and one-dimensional dielectric photonic crystals(PhCs)to increase the optical path length of light within the solar cells.This incorpo... We design an effective light trapping scheme through engineering metallic gratings and one-dimensional dielectric photonic crystals(PhCs)to increase the optical path length of light within the solar cells.This incorporation can result in broadband optical absorption enhancement not only for transverse magnetic polarized light but also for transverse-electric polarization.Even when no plasmonic mode can be excited,due to the high reflection of the PhCs,the absorption in the active region can still be enhanced.Rigorous coupled wave analysis results demonstrate that such a hybrid structure boosts the overall cell performance by increasing the light trapping capabilities and is especially effective at the silicon band edge.This kind of design can be used to increase the optical absorption over a wide spectral range and is relatively independent of the angle of incidence. 展开更多
关键词 absorption trapping transverse
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Atomic Layer Deposition of High-Capacity Anodes for Next-Generation Lithium-Ion Batteries and Beyond 认领 引用 被引量：1
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作者 Yanqiang Cao Xiangbo Meng Aidong Li 《Energy & Environmental Materials》 SCIE EI CAS CSCD 2021年第3期363-391,共29页
Electrification has great impacts on our modern society.To electrify future transportation,state-of-the-art lithium-ion batteries(LIBs)are still not sufficient in multiple aspects including cost,energy density,lifespa... Electrification has great impacts on our modern society.To electrify future transportation,state-of-the-art lithium-ion batteries(LIBs)are still not sufficient in multiple aspects including cost,energy density,lifespan,and safety.To this end,next-generation high-energy LIBs and beyond are highly regarded.In this regard,high-capacity anodes are undergoing intensive investigation,such as silicon,SnO2,and lithium metal.However,such anode materials are commonly experiencing large volume changes and related issues,which are reflected on mechanical degradation,capacity fading,low efficiency,and unsatisfactory lifetime.To address these challenges,many technical strategies have been investigated.In the past decade,atomic layer deposition(ALD)has emerged as a new promising technique enabling atomic-scale surface modification and nanoscale design of high-capacity anodes for high performance.In this review,recent ALD studies on developing high-capacity anodes for LIBs and beyond are thoroughly summarized.In addition,ALD strategies and their effectiveness in pursing high-energy LIBs and beyond are discussed.Particularly,we highlighted the latest advances of ALD for addressing the notorious issues associated with Li metal anodes.It is expected that this work will promote the applications of ALD in new battery systems. 展开更多
关键词 atomic layer deposition high-capacity anodes lithium-ion batteries and beyond nanostructured electrodes surface coating
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From stacking to function:Emergent states and quantum devices in 2D superconductor heterostructures 认领 引用
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作者 Sichun Zhao Junlin Xiong +3 位作者 Ji Zhou Shi-Jun Liang Bin Cheng Feng Miao 《Chinese Physics B》 SCIE EI CAS CSCD 2026年第6期87-110,共24页
Two-dimensional(2D)superconductors provide a powerful building block for engineering emergent quantum states shaped by reduced dimensionality,enhanced quantum fluctuations,and interfacial symmetry breaking.In van der ... Two-dimensional(2D)superconductors provide a powerful building block for engineering emergent quantum states shaped by reduced dimensionality,enhanced quantum fluctuations,and interfacial symmetry breaking.In van der Waals(vdW)heterostructures,atomically sharp and lattice-mismatch-free interfaces enable superconductivity to be deliberately coupled with magnetism,spin–orbit interaction,and band topology,allowing collective electronic orders to be combined and reconfigured in ways unattainable in bulk materials.This review summarizes recent advances in vdW heterostructures of 2D superconductors,focusing on superconductor/magnet(S/M),superconductoropological material(S/T),and superconductor/superconductor(S/S)junctions.We discuss the microscopic mechanisms underlying proximity effects and highlight how interfacial exchange fields,spin–orbit coupling,and twist-controlled tunneling give rise to unconventional pairing,long-range spin-triplet supercurrents,nonreciprocal Josephson transport,and topological superconductivity potentially hosting Majorana bound states.Beyond their fundamental significance,the ability to controllably generate topological and nonreciprocal superconducting states positions 2D superconductor heterostructures as promising building blocks for emerging quantum technologies,including ultra-sensitive quantum sensing,programmable superconducting logic,and energy-efficient quantum and neuromorphic computing architectures.Looking forward,advances in materials synthesis,interface engineering,and device integration are expected to further expand the scope and functionality of 2D superconductor heterostructures,reinforcing their role as a central platform for exploring and controlling emergent quantum phases. 展开更多
关键词 two-dimensional superconductor van der Waals heterostructures quantum device
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REGULARITIES AND SINGULARITIES OF THE ENERGY MINIMIZERS OF THE HEISENBERG GROUP TARGETS 认领 引用 被引量：1
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作者 贾高 《Acta Mathematica Scientia》 SCIE 2003年第4期447-452,共6页
In this paper, the properties of the maps for the Heisenberg group targets are studied. For u e∈W1,α(Ω, Hm), some Poincare type inequalities are proved. For the energy minimizers, the ∈-regularity theorems and the... In this paper, the properties of the maps for the Heisenberg group targets are studied. For u e∈W1,α(Ω, Hm), some Poincare type inequalities are proved. For the energy minimizers, the ∈-regularity theorems and the singularity theorems are obtained. 展开更多
关键词 Heisenberg group energy minimizer Legendrian map regularity singularity
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Numerical simulation and experimental investigation of Ti-6Al-4V melted by CW fiber laser at different pressures 认领 引用
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作者 Aasma Tabassum ZHOU Jie +2 位作者 HAN Bing NI Xiao-wu Maryam Sardar 《Optoelectronics Letters》 EI 2017年第4期299-303,共5页
The interaction of continuous wave （CW） fiber laser with Ti-6A1-4V alloy is investigated numerically and experi- mentally at different laser fluence values and ambient pressures of N2 atmosphere to determine the mel... The interaction of continuous wave （CW） fiber laser with Ti-6A1-4V alloy is investigated numerically and experi- mentally at different laser fluence values and ambient pressures of N2 atmosphere to determine the melting time threshold of Ti-6A1-4V alloy.＇ A 2D-axisymmetric numerical model considering heat transfer and laminar flow is es- tablished to describe the melting process. The simulation results indicate that material melts earlier at lower pressure （8.0 Pa） than at higher pressure （8.8x 104 Pa） in several milliseconds with the same laser fluence. The experimental results demonstrate that the melting time threshold at high laser fluence （above 1.89x 108 W/m2） is shorter for lower pressure （vacuum）, which is consistent with the simulation. While the melting time threshold at low laser fluence （below 1.89x 108 W/m2） is shorter for higher pressure. The possible aspects which can affect the melting process in- clude the increased heat loss induced by the heat conduction between the metal surface and the ambient gas with the increased pressure, and the absorption variation of the coarse surface resulted from the chemical reaction. 展开更多
关键词 Aluminum Fiber lasers Heat conduction Heat transfer Laminar flow Melting Metal melting Numerical models Ternary alloys Titanium alloys Tungsten alloys Vanadium alloys
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A Criterion for Stability of Synchronization and Application to Coupled Chua's Systems 认领 引用
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作者 WANG Hai-Xia LU Qi-Shao WANG Qing-Yun 《Communications in Theoretical Physics》 SCIE CAS 2009年第3期475-478,共4页
We investigate synchronization in an array network of nearest-neighbor coupled chaotic oscillators. By using of the Lyapunov stability theory and matrix theory, a criterion for stability of complete synchronization is... We investigate synchronization in an array network of nearest-neighbor coupled chaotic oscillators. By using of the Lyapunov stability theory and matrix theory, a criterion for stability of complete synchronization is deduced. Meanwhile, an estimate of the critical coupling strength is obtained to ensure achieving chaos synchronization. As an example application, a model of coupled Chua＇s circuits with linearly bidirectional coupling is studied to verify the validity of the criterion. 展开更多
关键词 synchronization Lyapunov function approach Lipschitz condition
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Design of periodic metal-insulator-metal waveguide back structures for the enhancement of light absorption in thin-film solar cells 认领 引用 被引量：5
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作者 郑改革 蒋剑莉 +3 位作者 咸冯林 强海霞 武虹 李相银 《Chinese Physics B》 SCIE EI CAS CSCD 2011年第9期192-197,共6页
To increase the absorption in a thin layer of absorbing material （amorphous silicon, a-Si）, a light trapping design is presented. The designed structure incorporates periodic metal-insulator-metal waveguides to enha... To increase the absorption in a thin layer of absorbing material （amorphous silicon, a-Si）, a light trapping design is presented. The designed structure incorporates periodic metal-insulator-metal waveguides to enhance the optical path length of light within the solar cells. The new design can result in broadband optical absorption enhancement not only for transverse magnetic （TM）-polarized light, but also for transverse electric （TE）-polarized light. No plasmonic modes can be excited in TE-polarization, but because of the coupling into the a-Si planar waveguide guiding modes and the diffraction of light by the bottom periodic structures into higher diffraction orders, the total absorption in the active region is also increased. The results from rigorous coupled wave analysis show that the overall optical absorption in the active layer can be greatly enhanced by up to 40%. The designed structures presented in this paper can be integrated with back contact technology to potentially produce high-efficiency thin-film solar cell devices. 展开更多
关键词 thin-film solar cells metal-insulator-metal waveguide enhanced optical absorption rig-orous coupled wave analysis
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Partition method for impact dynamics of flexible multibody systems based on contact constraint 认领 引用 被引量：8
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作者 段玥晨 章定国 洪嘉振 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI 2013年第11期1393-1404,共12页
The impact dynamics of a flexible multibody system is investigated. By using a partition method, the system is divided into two parts, the local impact region and the region away from the impact. The two parts are con... The impact dynamics of a flexible multibody system is investigated. By using a partition method, the system is divided into two parts, the local impact region and the region away from the impact. The two parts are connected by specific boundary conditions, and the system after partition is equivalent to the original system. According to the rigid-flexible coupling dynamic theory of multibody system, system＇s rigid-flexible coupling dynamic equations without impact are derived. A local impulse method for establishing the initial impact conditions is proposed. It satisfies the compatibility con- ditions for contact constraints and the actual physical situation of the impact process of flexible bodies. Based on the contact constraint method, system＇s impact dynamic equa- tions are derived in a differential-algebraic form. The contact/separation criterion and the algorithm are given. An impact dynamic simulation is given. The results show that system＇s dynamic behaviors including the energy, the deformations, the displacements, and the impact force during the impact process change dramatically. The impact makes great effects on the global dynamics of the system during and after impact. 展开更多
关键词 flexible multibody system impact dynamics partition method impulse-momentum method contact constraint
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Determination of Aluminum in Nickel-Based Superalloys by Using Laser-Induced Breakdown Spectroscopy 认领 引用 被引量：3
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作者 朱德华 王茜 +2 位作者 倪晓武 陈建平 陆建 《Plasma Science and Technology》 SCIE EI CAS CSCD 2011年第4期486-489,共4页
Laser-induced breakdown spectroscopy （LIBS） was developed to detect aluminum in nickel-based superalloys （K417, GH4033, DZ125L, З ∏742y） using a non-intensified, non-gated, low-cost detection system. The precisi... Laser-induced breakdown spectroscopy （LIBS） was developed to detect aluminum in nickel-based superalloys （K417, GH4033, DZ125L, З ∏742y） using a non-intensified, non-gated, low-cost detection system. The precision of LIBS depends strongly on the experimental conditions. The calibration curves of Al（I）394.4 nm and Al（I）396.2 nm under the optimum experimental parameters are presented. Finally the limit of detection （LOD） for aluminum is calculated from the experimental data, which is in the range of 0.09% to 0.1% by weight. 展开更多
关键词 aluminum emission lines LIBS nickel based superalloys calibration curve limit of detection
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Dynamic compressive response of porcine muscle measured using a split Hopkinson bar system with a pair of PVDF force transducers 认领 引用 被引量：2
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作者 Yao-ke Wen Liang Xu +2 位作者 Ai-jun Chen Fang-dong Dong Bin Qin 《Defence Technology（防务技术）》 SCIE EI CAS CSCD 2023年第10期298-305,共8页
The classic metallic Split Hopkinson Pressure Bar(SHPB)cannot capture the transmitted signal accurately when measuring soft biological tissue,because of the very low wave impedance and strength of this material.So the... The classic metallic Split Hopkinson Pressure Bar(SHPB)cannot capture the transmitted signal accurately when measuring soft biological tissue,because of the very low wave impedance and strength of this material.So the dynamic compressive response of porcine muscle has been investigated by using a modified SHPB.The forces on both ends of the sample measured using Polyvinylidene fluor(PVDF)transducers were applied to calculate the stress in the specimen instead of the strain gauge signal on the transmitted bar.Moreover,a circular cardboard disk pulse shaper was applied for generating a suitable incident pulse to achieve stress equilibrium and constant strain rates in the specimens.Then,the dynamic mechanical properties of porcine muscle parallel and perpendicular to the fiber directions were measured,and the stress equilibrium process during loading was analyzed,as well as the inertia-induced extra stress being corrected.Furthermore,quasi-static tests were conducted at two different strain rates to investigate the strain rate dependence using a universal material testing machine.The results show that the stress-strain curves are sensitive to strain rate in the two different loading directions.The compressive stress perpendicular to the fiber direction is stiffer than that parallel to the fiber direction.In addition,a strain rate-dependent constitutive model was developed based on the mechanical response of the muscle at different strain rates and fitted to the experimental data.The results show that the overall fit is good,and the constitutive model could describe the muscle's dynamic mechanical properties. 展开更多
关键词 PVDF Hopkinson bar Porcine muscle Dynamic mechanical properties Constitutive model
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Effect of rifle bullet parameters on the penetration into ballistic gelatin 认领 引用 被引量：4
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作者 刘苏苏 徐诚 +1 位作者 陈爱军 李宏魁 《Journal of Beijing Institute of Technology》 EI CAS 2015年第4期487-493,共7页
To understand the effects of the rifle bullet parameters on the bullet-gelatin interaction quantitatively, a finite element model of bullet penetrating gelatin was set up and computational re- suits are compared with ... To understand the effects of the rifle bullet parameters on the bullet-gelatin interaction quantitatively, a finite element model of bullet penetrating gelatin was set up and computational re- suits are compared with experimental ones. The penetration of the rifle bullet into the gelatin was simulated by the nonlinear finite element method. The quantitative analysis of the changes in the ge- latin interaction with the rifle bullet were conducted by changing the bullet parameters, such as at- tack angle on gelatin, initial velocity, warhead＇ s tip and location of mass center of bullet. Results demonstrate that with the increase of the attack angle, instable moment of the bullet moves forward, the length of narrow wound channel shortens, and when penetration is completed diameters of tem- porary cavities increase, the gelatin energy and energy transmission ratio increases; With the in- crease of the impact velocity, instable moment of the bullet moves forward, the maximum forces acting on the gelatin and the gelatin energy increase remarkably ; the length of narrow wound channel shortens, diameters of temporary cavities increase when penetration is completed, the gelatin energy and energy transmission ratio increase; The warhead＇ s tip and location of mass center have a influ- ence on the instable moment of the bullet and length of the narrow wound channel. The instable mo- ment delays and narrow wound channel increases when the warhead＇s tip flattens. The instable mo- ment moves forward a little and the narrow wound channel shortens a little when location of mass center moves back. 展开更多
关键词 bullet gelatin penetration temporary cavity
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