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A brief review of metamaterials for opening low-frequency band gaps

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Applied Mathematics and Mechanics(English Edition) 2022年第7期43卷 1125-1144页

作者： Kai WANG Jiaxi ZHOU Dongguo TAN Zeyi LI Qida LIN daolin xu College of Mechanical and Vehicle Engineering Hunan UniversityChangsha 410082China Research Institute of Hunan University in Chongqing Chongqing 401133China

Metamaterials are an emerging type of man-made material capable of obtaining some extraordinary properties that cannot be realized by naturally occurring *** to tremendous application foregrounds in wave manipulations,metamaterials have gained more and more ***,developing research interest of low-frequency vibration attenuation using metamaterials has emerged in the past *** better understand the fundamental principle of opening low-frequency(below 100 Hz)band gaps,a general view on the existing literature related to low-frequency band gaps is *** this review,some methods for fulfilling low-frequency band gaps are firstly categorized and detailed,and then several strategies for tuning the low-frequency band gaps are ***,the potential applications of this type of metamaterial are briefly *** review is expected to provide some inspirations for realizing and tuning the low-frequency band gaps by means of summarizing the related literature.

关键词： metamaterial low-frequency band gap vibration suppression

Modeling and analysis of the friction in a non-linear sliding-mode triboelectric energy harvester

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Acta Mechanica Sinica 2022年第4期38卷 189-206,I0004页

作者： Dongguo Tan Jiaxi Zhou Kai Wang Changqi Cai daolin xu College of Mechanical and Vehicle Engineering Hunan UniversityChangsha 410082China Chongqing Institute of Hunan University Chongqing 401133China

Friction plays a pivotal role in the sliding-mode triboelectric energy harvester(TEH),which not only enables the charge transfer between two dielectrics,but also influences the energy harvesting performance by affecting the dynamic response of the *** to evaluate the effects of the friction on TEHs is important for optimizing TEHs in engineering *** order to analyze the effects of the friction on the dynamic response and evaluate the energy harvesting performance ofTEHs,the paper models the friction of a devised non-linear TEH based on the Coulomb friction model and the Macro-slip friction *** TEH equips a pair of magnets,rendering a switching between the bistability and the monostability by tuning the distance between two *** dynamic model of the non-linear TEH is established by the extended Hamilton *** effects of friction in slidingmode TEH are dissected in *** influences of parameters on both the mechanical and electrical responses are also systemically studied to explore an optimal energy harvesting performance in the low-frequency *** work provides a guideline for designing and accurately analyzing a sliding-mode TEH.

关键词： Triboelectric energy harvester Magnetic bistability Macro-slip friction model Coulomb friction model Nonlinearity

Design and experimental study of a compact quasi-zero-stiffness isolator using wave springs

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Science China(Technological Sciences) 2021年第10期64卷 2255-2271页

作者： WANG Qiang ZHOU JiaXi WANG Kai xu daolin WEN GuiLin State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Changsha 410082China College of Mechanical and Vehicle Engineering Hunan UniversityChangsha 410082China School of Mechanical and Electric Engineering Guangzhou UniversityGuangzhou 510006China

The quasi-zero-stiffness(QZS)vibration isolation has been proven to be an effective way to isolate low-frequency ***,most of the existing QZS isolators are space-consuming,which could not be employed in the space-limited *** this paper,a quite compact QZS isolator is engineered by connecting a pair of mutually repulsive magnet rings and a space-saving wave spring in parallel,called WQZS *** restoring force of the magnet ring is derived by the equivalent magnetic charge method,and an empirical formula for the restoring force of the wave spring is derived by the least squares method based on experimental *** dynamic model of the WQZS vibration isolation system is built,and the vibration isolation performance is evaluated through ***,an experimental prototype is fabricated,and the experimental tests on frequency sweep are carried *** results show that compared with the linear counterpart,the vibration isolation frequency of the WQZS isolator is reduced by 48.89%,and the peak transmissibility is decreased by 59.33%.Most importantly,the space occupancy of the WQZS isolator designed in this paper is much lower than that of the traditional QZS isolators,and thus it should be a potential solution for low-frequency vibration isolation in the space-limited environment.

关键词： quasi-zero-stiffness vibration isolator space saving magnet rings wave spring

Numerical and Experimental Investigations on Tunable Low-frequency Locally Resonant Metamaterials

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Acta Mechanica Solida Sinica 2021年第5期34卷 612-623页

作者： Qida Lin Jiaxi Zhou Hongbin Pan daolin xu Guilin Wen State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Changsha410082China College of Mechanical and Vehicle Engineering Hunan UniversityChangsha410082China School of Mechanical and Electric Engineering Guangzhou UniversityGuangzhou510006China

In this paper,a tunable locally resonant metamaterial is proposed for low-frequency band *** local resonator composed of two pairs of folded slender beams and a proof mass is designed based on the theory of compliant *** design optimization on geometric parameters is carried out to fulfil the quasi-zero-stiffness *** locally resonant metamaterial is formed by periodically arranged unit cells,and the transmittance of longitudinal wave is studied through three aspects:numerical predictions,finite element simulations and experimental *** variation trends revealed by these three methods match well with one another:the band gap moves to lower frequency and both its depth and width get smaller and smaller with the increase of pre-compression(Δ).The band gap overlays the frequency range of 73.10–92.38 Hz and 16.78–19.49 Hz atΔ=0mm andΔ=10mm,respectively,providing a wide range of ***,the ultralow-frequency band gap can be achieved asΔapproaches 10 *** study may provide an avenue for achieving the tunable ultralow-frequency locally resonant band gap.

关键词： Acoustic metamaterial Locally resonant band gap Tunability and ultralow frequency Quasi-zero stiffness

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低频弹性波超材料的若干进展

力学学报 2022年第10期54卷 2678-2694,I0001页

作者：王凯周加喜蔡昌琦徐道临文桂林湖南大学机械与运载工程学院长沙410082 湖南大学重庆研究院重庆401133 燕山大学机械工程学院河北秦皇岛066004

超材料是一类新兴的具有超常物理性质的人造周期/拟周期材料,能够改变电磁波、声波以及弹性波等在介质中的传播特性.因在航天、国防以及民用科学等方面的巨大应用潜力,超材料自被提出后便受到极大的关注并引发研究热潮.弹性波超材料是... 详细信息

超材料是一类新兴的具有超常物理性质的人造周期/拟周期材料,能够改变电磁波、声波以及弹性波等在介质中的传播特性.因在航天、国防以及民用科学等方面的巨大应用潜力,超材料自被提出后便受到极大的关注并引发研究热潮.弹性波超材料是超材料的一种,能够基于弹性波与超材料结构的相互耦合作用实现对弹性波的操控.带隙是评估弹性波超材料实现弹性波操控的重要工具,其性质与超材料的材料参数、晶格常数以及局域振子的固有频率相关.受制于超材料的承载能力、外观尺寸以及局域振子结构等因素,利用传统超材料开启低频(约100 Hz)弹性波带隙依然存在较大困难.文章首先简要介绍超材料开启弹性波带隙的基本原理,然后从低频弹性波超材料基本结构与低频带隙实现方法、低频带隙优化与调控策略、低频带隙潜在应用等三个方面详细总结低频弹性波超材料的研究工作.其中,低频带隙超材料的基本结构主要包括布拉格散射型超材料、传统局域共振型超材料以及准零刚度局域共振超材料.文章通过总结低频弹性波超材料的研究进展,分析了目前研究中的不足并对未来低频弹性波的研究方向进行了展望.

关键词：超材料低频带隙准零刚度带隙调控振动抑制

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双层主动隔振系统优化设计方法研究

动力学与控制学报 2022年第1期20卷 35-41页

作者：昌耀鹏周加喜徐道临湖南大学机械与运载工程学院长沙410082

在主动隔振系统中,执行机构输出的主动控制力与系统隔振性能密切联系.为研究上述问题,本文通过建立优化目标函数对双层主动隔振系统进行优化来获得最优系统参数,分析优化前后双层主动隔振系统的隔振性能及主动控制力,验证优化方法的可性... 详细信息

在主动隔振系统中,执行机构输出的主动控制力与系统隔振性能密切联系.为研究上述问题,本文通过建立优化目标函数对双层主动隔振系统进行优化来获得最优系统参数,分析优化前后双层主动隔振系统的隔振性能及主动控制力,验证优化方法的可性行.首先,从理论上研究了双层主动隔振系统在不同激励条件下的隔振性能,并分析了系统参数对主动控制力输出的影响.其次,建立综合性的优化目标评价系统的隔振性能,利用遗传算法优化目标函数.最后,利用模糊PID控制算法对双层主动隔振系统进行主动控制,对比优化前后的隔振性能及主动控制力,其结果表明:优化后,隔振对象的位移,与中间层的相对位移及主动控制力分别减小了32.7%,67.5%,55.4%.因此,双层主动隔振系统的优化设计方法是可行的.

关键词：主动隔振参数分析优化设计遗传算法

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考虑系统延时的无人船路径跟踪控制

中国造船 2023年第5期64卷 249-258页

作者：陈昱衡张海成邹伟生祁立波徐道临湖南大学机械与运载工程学院长沙410082

针对无人船因控制系统延时而导致的路径跟踪性能退化,提出计及系统延时的路径跟踪控制策略,并设计了基于模型预测控制算法的双层路径跟踪控制器。基于线性模型预测控制算法,设计了USV运动学控制器,以此减小无人船路径跟踪偏差并得到期... 详细信息

针对无人船因控制系统延时而导致的路径跟踪性能退化,提出计及系统延时的路径跟踪控制策略,并设计了基于模型预测控制算法的双层路径跟踪控制器。基于线性模型预测控制算法,设计了USV运动学控制器,以此减小无人船路径跟踪偏差并得到期望速度。将系统延时处理为一阶系统,并将其和无人船的动力学模型耦合。基于非线性模型预测控制,设计了USV动力学控制器,用于响应无人船的期望速度。数值仿真结果表明,在存在系统延时的仿真环境中,论文提出的针对控制系统延时的处理策略可减小无人船的路径跟踪偏差和改善控制形态输入的平顺性。

关键词：无人船路径跟踪模型预测控制延时系统

Riverine sulfate sources and behaviors in arid environment,Northwest China:Constraints from sulfur and oxygen isotopes

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Journal of Environmental Sciences 2024年第3期137卷 716-731页

作者： Yifu xu Wenjing Liu Bing xu Zhifang xu Key Laboratory of Cenozoic Geology and Environment Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China Innovation Academy for Earth Science Chinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences Beijing 100049China

The fate of riverine sulfate ion (SO_(4)^(2-)) and its environmental effects in arid environment are difficult to evaluate due to its complicated sources and strongly coupled behaviors with water cycle which is significantly modified by *** understand the sulfur cycle in aquatic systems in arid environment,the chemical and sulfur and oxygen isotopic compositions (δ^(34)S_(SO4)and δ^(18)O_(SO4)) of major rivers around the Badain Jaran Desert,northwestern China,were *** rivers had averaged SO_(4)^(2-)content at 1336μmol/L,over 10times higher than the global *** δ^(34)S_(SO4)and δ^(18)O_(SO4)values ranged from-5.3‰to+11.8‰and+1.6‰to+12.8‰,*** end-member analysis and the inverse model showed that riverine sulfate was mainly derived from evaporites dissolution (0-87%),sulfide oxidation (13%-100%) and precipitation (0-33%),indicating heterogeneity in sulfur sources and behaviors along the river drainage with the lithology variations and climate *** isotopic tools combining with hydro-chemistry compositions could be applied to reveal sulfur cycle in arid *** on the calculation,sulfide oxidation plays the primary role in the headwater and upstream in the Qilian-Mountains area,where sulfide is widely *** the proportion of evaporites dissolution contributing to riverine sulfate is much higher in downstream in a drier ***,less precipitation and higher temperature can lead to more intensive evaporation,affecting the process of sulfide oxidation and enhancing the rates of evaporites dissolution and sulfate precipitation in the basin.

关键词： Sulfur and oxygen isotopes Source apportionment Inverse model Arid environment Inland rivers Northwestern China

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非线性铰接浮体波能转换器的动力学特性研究

海洋工程 2023年第5期41卷 57-69页

作者：刘家瑞张海成周潇徐道临湖南大学机械与运载工程学院湖南长沙410082 中国船舶科学研究中心江苏无锡214082

针对传统铰接浮体波能转换器捕获效率低、频带窄的瓶颈,提出一种新型高效波能捕获仿生非线性连接结构。该连接结构具有转动负刚度效应,可起到被动相位控制作用,提高系统的波能捕获效率。首先,基于海蛇脊柱骨结构的柔性约束机理,设计了... 详细信息

针对传统铰接浮体波能转换器捕获效率低、频带窄的瓶颈,提出一种新型高效波能捕获仿生非线性连接结构。该连接结构具有转动负刚度效应,可起到被动相位控制作用,提高系统的波能捕获效率。首先,基于海蛇脊柱骨结构的柔性约束机理,设计了一种高效波浪能捕获仿生连接结构,该结构由球窝结构、球头、翅状突出物和类肌肉柔性结构组成;其次,基于线性波浪理论和Cummins方程,建立两模块非线性波能转换器的动力学模型,并采用谐波平衡法解析求解非线性控制方程;最后,开展了数值模拟研究,分析了规则波激励下该新型波能转换器的波能转换特性。结果表明:通过引入新型高效仿生连接结构,可有效降低系统的等效固有频率;当连接器的负刚度结构调整到合适参数时,系统的弹性力可以在纵摇相平面上形成一个椭圆势阱,其椭圆势阱的长轴接近铰接浮体系统相对纵摇运动的模态方向,由此驱动两个模块的相对纵摇运动趋于反相,起到被动相位控制的作用。

关键词：波浪能铰接浮体波能转换器连接结构捕获效率