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Low-frequency chatter suppression in robotic milling using Magnetorheological Joint Damper(MRJD)

Chinese Journal of Aeronautics 2025年第3期38卷 521-543页

作者： Shihao XIN Xiaowei TANG Jiawei WU Fangyu PENG Rong YAN Kai SUN School of Mechanical Science and Engineering Huazhong University of Science and TechnologyWuhan 430074China State Key Laboratory of Intelligent Manufacturing Equipment and Technology Huazhong University of Science and TechnologyWuhan 430074China

Low-frequency structural vibrations caused by poor rigidity are one of the main obstacles limiting the machining efficiency of robotic *** vibration suppression strategies primarily focus on passive vibration absorption at the robotic end and feedback control at the joint *** these strategies have a certain vibration suppression effect,the limitations of robotic flexibility and the extremely limited applicable speed range remain to be *** this study,a Magnetorheological Joint Damper(MRJD)is *** joint-mounted feature ensures machining flexibility of the robot,and the millisecond response time of the Magnetorheological Fluid(MRF)ensures a large effective spindle speed *** importantly,the evolution law of the damping performance of MRJD was revealed based on a low-frequency chatter mechanism,which guarantees the application of MRJD in robotic milling *** analyze the influence of the robotic joint angle on the suppression effect of the MRJD,the joint braking coefficient and end braking coefficient were *** coordinate plots were used to visualize the joint range with the optimal vibration suppression ***,a combination of different postures and cutting parameters was used to verify the vibration suppression effect and feasibility of the joint angle *** experimental results show that the MRJD,which directly improves the joint vibration resistance,can effectively suppress the low-frequency vibration of robotic milling under a variety of cutting conditions.

关键词： Magnetorheological fluids Joint damper Vibration suppressioni Low-frequency chatter Robotic milling

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Mesoscale study on explosion-induced formation and thermochemical response of PTFE/Al granular jet

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Defence technology（防务技术） 2023年第5期23卷 112-125页

作者： Yuan-feng Zheng Zhi-jian Zheng Guan-cheng Lu Hai-fu Wang Huan-guo Guo State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081China

The dynamic formation,shock-induced inhomogeneous temperature rise and corresponding chemical reaction behaviors of PTFE/Al reactive liner shaped charge jet(RLSCJ)are investigated by the combination of mesoscale simulation,reaction kinetics and chemical energy release test.A two-dimensional granular model is developed with the randomly normal distribution of aluminum particle sizes and the particle delivery ***,the granular model is employed to study the shock-induced thermal behavior during the formation and extension processes of RLSCJ,as well as the temperature history curves of aluminum *** simulation results visualize the motion and temperature responses of the RLSCJ at the grain level,and further indicate that the aluminum particles are more likely to gather in the last two-thirds of the jet along its *** analysis shows that the shock,collision,friction and deformation behaviors are all responsible for the steep temperature rise of the reactive *** addition,a shock-induced chemical reaction extent model of RLSCJ is built based on the combination of the Arrhenius model and the Avrami-Erofeev kinetic model,by which the chemical reaction growth behavior during the formation and extension stages is described *** model indicates the reaction extent highly corresponds to the aluminum particle temperature history at the formation and extension *** last,a manometry chamber and the corresponding energy release model are used together to study the macroscopic chemical energy release characteristics of RLSCJ,by which the reaction extent model is verified.

关键词： Reactive materials Shaped charge Mesoscale simulation Formation Thermochemical response

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Coupling effect on the thermal hazard assessment of hazardous chemical materials via calorimetric technologies and simulation approaches

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Defence technology（防务技术） 2024年第2期32卷 644-654页

作者： Yabei Xu Jiankun Shao Wei Wang Shengliang Xu Dongping Chen State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China Science and Technology on Aerospace Chemical Power Laboratory Hubei Institute of Aerospace ChemotechnologyXiangyang 441003China

The coupling effect of heat absorption and release exists in the thermal decomposition of a few chemical ***,the impact of the above coupling on thermal hazard assessment is not considered in the literature *** this work,nitroguanidine(NQ)and 1,3,5-trinitro-1,3,5-triazine(RDX)are selected as representative materials to explore the influence of the coupling effect on the thermal hazard assessment of chemical *** linear heating experiments of NQ and RDX are carried out by a microcalorimeter and synchronous thermal *** thermal decomposition curves are decoupled by advanced thermokinetics *** thermal decomposition and kinetic parameters before and after decoupling are *** results of TG experiment show that both NQ and RDX began to lose mass during the endothermic *** endothermic melting and exothermic decomposition of NQ and RDX are coupled within this *** coupling effect has different degrees of influence on its initial decomposition temperature and safety *** with the parameters in the coupling state,the initial decomposition temperature and adiabatic induction period after decoupling *** self-accelerating decomposition temperature increases,and internal thermal runaway time *** the thermal hazard assessment of chemical materials with coupling effects,the calculated parameters after decoupling should be taken as an important safety index。

关键词： Calorimetric technologies Kinetics Thermal hazard Phase transformation Thermal decomposition

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Fast thermal responsive separators toward long-life and safe lithium metal batteries

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Nano Research 2024年第4期17卷 2746-2754页

作者： Pingan Li Zhifang Liu Yitong Peng Shanshan Yang Tao Meng Yunhuan Hu Yingjun Jiang Hao Sun Qi Li Xianluo Hu State Key Laboratory of Materials Processing and Die and Mould Technology School of Materials Science and EngineeringHuazhong University of Science and TechnologyWuhan 430074China

Lithium metal batteries(LMBs)have been extensively investigated during the past decades because of their ultrahigh energy *** the increasing demand for energy density,however,the safety issue of LMBs has become a significant *** particular,localized areas of increased temperature(namely,hotspots)may be induced and even exacerbated within LMBs by uneven current distribution,internal short circuits,or inadequate heat dissipation,which significantly sacrifices battery safety and cycle ***,we report the rational design and fabrication of a fast thermal responsive separator capable of inhibiting the growth of lithium dendrites and mitigating thermal propagation,thereby reducing the risk of thermal *** as-achieved separator comprises both an electrospun membrane using a phase change material with superior thermal-storage ability and a thermally conductive modification layer of hexagonal boron nitride nanosheets with a fast heat-transfer *** is demonstrated that such a unique integration of heat conduction and heat storage enables the functional separator with attractive abilities to mitigate hotspots and inhibit the growth of lithium dendrites upon the cycling of ***,pouch cells with the thermal-responsive separator,as well as numerical simulations,verify much enhanced safety and cycle life of *** work may offer a new conceptual design of intelligent separators that acts as a functional unit encapsulated within a single cell to boost in-situ thermal management,which will help to develop high-safety and energy-dense LMBs.

关键词： lithium metal batteries separators hotspots safety thermal management

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Combustion crack-network reaction evolution model for highly-confined explosives

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Defence technology（防务技术） 2023年第8期26卷 54-67页

作者： Zhuo-ping Duan Meng-Jing Bai Zhi-ling Bai Xin-jie Wang Feng-lei Huang State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081China

The evolution behavior of combustion crack reaction of highly confined solid explosives after non-shock ignition is governed by multiple dynamic processes,including intrinsic combustion of explosives,crack propagation,and rapid growth of combustion surface ***,the pressure increase can accelerate the combustion rate of explosives,and the crack propagation can enlarge the combustion surface *** coupling between these two effects leads to the self-enhanced combustion of explosive charge system,which is the key mechanism for the reaction development after *** this study,combustion cracknetwork(CCN) model is established to describe the evolution of combustion crack reaction of highly confined solid explosives after non-shock ignition and quantify the reaction *** feasibility of the model is verified by comparing the computational and experimental *** results reveal that an increase in charge structure size causes an increase in the time of crack pressurization and extension of cracks due to the high temperature-generated gas flow and surface combustion during the initial stage of explosive reaction,but when the casing is fractured,the larger the charge structure,the more violent the late reaction and the larger the charge reaction *** input pressure has no obvious influence on the final reaction ***,a larger venting hole area leads to better pressure relief effect,which causes slower pressure growth inside *** reserved ullage volume causes longer lowpressure induction stage,which further restrains the internal pressure ***,the stronger the casing constraint,the more rapid the self-enhanced combustion of the high temperaturegenerated gas,which results in more violent charge reaction and larger charge reaction degree during casing ***,the proposed model can clarify the effects of intrinsic combustion rate of explosives,charge structure size,input pressure,relief area,ullage volume,a

关键词： Solid explosives Non-shock ignition Self-enhanced combustion Combustion crack-network(CCN)model Relief area Reaction degree

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Reactive jet density distribution effect on its penetration behavior

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Defence technology（防务技术） 2023年第6期24卷 190-202页

作者： Huan-guo Guo Cheng-hai Su Yi-qiang Cai Suo He Qing-bo Yu Haifu Wang State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing100081China

In this paper,the penetration mechanism of reactive jet with non-uniform density distribution is *** simulations show that the density deficit occurs in the whole reactive jet,and the density increases from the jet tip to *** density of jet tip is approximately 1.5 g/cm3,which is lower than that of the reactive liner *** X-ray experiments show similar results with the *** density decreasing effect of jet tip has a significant influence on the penetration behavior when the reactive jet impacts steel *** to the simulation results,this paper assumes that the density gradient in the jet section has linear ***,the deflagration pressure generated by each jet element at the bottom of crater is introduced into the Bernoulli *** on the virtual origin model and Szendrei-Held equation,the analytical models for penetration depth and radial cratering of reactive jet with the density reduction are ***,to further prove the validity of analytical models,the penetration experiments of the reactive liner shaped charge against steel plate under different standoffs are carried *** is a convergence between the analytical crater profiles and experimental results when reactive jets penetrate steel plates under different standoffs,especially at standoff of 1.5 and 2.0charge diameters.

关键词： Shaped charge Reactive jet Density distribution Jet penetration Virtual origin

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Dynamics of three ferrofluid droplets in a rotating magnetic field

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Applied Mathematics and Mechanics(English Edition) 2025年第3期46卷 591-600页

作者： Xinping ZHOU Wencai XIAO Qi ZHANG Chunyue LIANG Wanqiu ZHANG Fei ZHANG School of Mechanical Science and Engineering Huazhong University of Science and TechnologyWuhan 430074China State Key Laboratory of Intelligent Manufacturing Equipment and Technology Huazhong University of Science and TechnologyWuhan 430074China

Two-dimensional(2D)direct numerical simulations on the dynamics of three identical ferrofluid droplets suspended in a non-magnetic ambient fluid under a rotating uniform magnetic field are conducted,and the motion and deformation of the three ferrofluid droplets are studied in this *** show that there are four modes(i.e.,the three droplets'direct coalescence(TC),the coalescence of two droplets and the subsequent planetary motion with the third droplet(CAP),the three droplets'planetary motion(TP),and the independent spin(IS))for the three ferrofluid droplets,dependent on the magnetic Bond number(Bom)and the initial distance(d0)between two of the *** is found that the decrease in d0and the increase in Bomcan make the droplets'mode change from the IS to the planetary motion,and then turn to the ***,reducing Bomor d0is helpful for the droplets to become merged.

关键词： ferrofluid droplet rotating magnetic field capillary force

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A vibration isolator with a controllable quasi-zero stiffness region based on nonlinear force design

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Applied Mathematics and Mechanics(English Edition) 2024年第8期45卷 1279-1294页

作者： Xinyu LIAN Bing LIU Huaxia DENG Xinglong GONG CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern MechanicsUniversity of Science and Technology of ChinaHefei 230027China State Key Laboratory of Nonlinear Mechanics Institute of MechanicsChinese Academy of SciencesBeijing 100190China State Key Laboratory of Fire Science University of Science and Technology of ChinaHefei 230026China

To achieve stability optimization in low-frequency vibration control for precision instruments,this paper presents a quasi-zero stiffness(QZS)vibration isolator with adjustable nonlinear ***,the stress-magnetism coupling model is established through meticulous theoretical *** controllable QZS interval is constructed via parameter design and magnetic control,effectively segregating the high static stiffness bearing section from the QZS vibration isolation ***,a displacement control scheme utilizing a magnetic force is proposed to regulate entry into the QZS working range for the vibration isolation *** results demonstrate that the operation within this QZS region reduces the peak-to-peak acceleration signal by approximately 66.7%compared with the operation outside this region,thereby significantly improving the low frequency performance of the QZS vibration isolator.

关键词： low frequency nonlinear vibration isolator quasi-zero stiffness(QzS)

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DCM-based dynamic stable walking under terrain-induced time-varying disturbances for humanoid robots

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science China(Technological sciences) 2025年第4期68卷 105-117页

作者： Yan LUO Chao LIU Jianhua WU Zhenhua XIONG Han DING State Key Laboratory of Mechanical System and Vibration School of Mechanical EngineeringShanghai Jiao Tong UniversityShanghai200240China State Key Laboratory of Intelligent Manufacturing Equipment and Technology School of Mechanical Science and EngineeringHuazhong University of Science and TechnologyWuhan430074China

When humanoid robots attempt to walk on terrain such as shaking platforms,time-varying disturbances are introduced to the support *** abrupt changes of inclination angle can cause the robot to lose balance upon landing,presenting significant challenges for balance control *** address this issue,we propose a novel divergent component of motion(DCM)-based time-varying disturbance walking(DCM-TVDW)*** method allows the robot to walk on rugged surfaces and helps to maintain dynamic balance when subjected to large time-varying *** the DCM-TVDW control method,we first adjust the robot's center of mass and stride height to adapt to transitions between different terrain types via a variable height stabilization method,and hold these quantities constant as base *** then combine DCM with the N-step capturability *** combination allows for dynamic balance through multi-step adjustments from the initially unstable region,thereby extending the robots stability *** and experimental results demonstrate that the DCM-TVDW method enables the SJ-Bruce robot to traverse a dynamically shaking platform with an inclination angle of approximately 22°.

关键词： humanoid robot dynamic balance control capturability time-varying disturbance

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Poly(vinylidene fluoride)of Differentβ-Phase/γ-Phase Ratio Prepared by Heat Controlled Spin Coating and Potassium Bromide as Nucleating Agent

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Chinese Journal of Polymer science 2025年第5期43卷 769-777页

作者： Hai-Peng Li Jia-Meng Liang Hao-Ying Song Han-Qi Zhu Wen-Peng Zhao Shao-Juan Wang Hao Zhang Shou-Ke Yan Key Laboratory of Rubber-Plastics Qingdao University of Science&TechnologyQingdao266042China School of Chemical Engineering Key Laboratory of Rubber-PlasticsQingdao University of Science&TechnologyQingdao266042China State Key Laboratory of Chemical Resource Engineering Beijing University of Chemical TechnologyBeijing100029China

Herein,a simple method for preparing poly(vinylidene fluoride)(PVDF)films with controlledβ/γratios by spin-coating assisted by potassium bromide(KBr)is *** results show that the relative fraction of theβphase(denoted as Fβ)for the films prepared on the KBr surface first decreased until a critical temperature(denoted as Tc)was reached,and then increased with increasing spin-coating *** was related to the dissolved K and Br ions in the *** experiments showed that below Tc,high humidity can enhance Fβbut exhibit an adverse effect at and above *** high content of K and Br ions in the PVDF/KBr blend film and larger shear stress can facilitate the formation of theβphase,leading exclusively to the formation ofβ-andγ-*** mechanism responsible for the change in Fβwith temperature was proposed:below Tc,the decrease in water intake with increasing temperature results in the decline of Fβ,whereas above Tc,the increase in Fβwith temperature is attributed to the synergistic effect of ions and shear ***,this paves the way for fabricating PVDF films with tailoredβ/γratios for electroactive and energy-harvesting applications.

关键词： Poly(vinylidene fluoride) KBr Spin coating Polymorph

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