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Electromechanical Fields Near a Circular PN Junction Between Two Piezoelectric Semiconductors

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Acta Mechanica Solida Sinica 2018年第2期31卷 127-140页

作者： Yixun Luo Ruoran Cheng Chunli Zhang Weiqiu Chen Jiashi Yang Department of Engineering Mechanics Zhejiang University Hangzhou 310027 Zhejiang China Department of Mechanical and Materials Engineering University of Nebraska-Lincoln Lincoln NE 68588-0526 USA soft Matter Research Center (SMRC) Zhejiang University Hangzhou 310027 China key laboratory of soft machines and smart devices of zhejiang province Hangzhou 310027 China

We study electromechanical fields near the interface between a circular piezoelectric semiconductor cylinder and another piezoelectric semiconductor in which it is embedded. The cylinder is p-doped. The surrounding material is n-doped. The phenomenological theory of piezoelectric semiconductors consisting of the equations of piezoelectricity and the conservation of charge for holes and electrons is used. The theory is linearized for small carrier concentration perturbations. An analytical solution is obtained, showing the formation of a PN junction near the interface. Various electromechanical fields associated with the junction are calculated. The effects of a few physical parameters are examined.

关键词： Piezoelectric semiconductors Cylinder Carriers PN junction Electromechanical coupling

Micromechanical simulation on strength and ductility of two kinds of Al-based nanostructural materials

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Acta Mechanica Solida Sinica 2017年第4期30卷 404-415页

作者： Xu He Linli Zhu Jinling Liu Linan An State key laboratory of Traction Power Southwest Jiaotong University Applied Mechanics and Structure Safety key laboratory of Sichuan province School of Mechanics and EngineeringSouthwest Jiaotong University Department of Engineering Mechanics and key laboratory of soft machines and smart devices of zhejiang province Zhejiang University Department of Materials Science and Engineering and Advanced Materials Processing and Analysis Center University of Central Florida

The nanostructured Al-based composites possess the combination of high yield strength and good ductility. In this paper, a micromechanical model is presented to simulate the mechanical response of bimodal nanostructured A1 and the particle-reinforced aluminum matrix composite （PAMC）. The constitutive relations for different phases are addressed in the model, as well as the contribution of microcracks. Numerical results show that the model can successfully describe the enhanced strength and ductility of the bimodal nanostructured AI, and the predictions of the PAMC are in good agreement with the experimental data. It is worth noting that the strength and ductility are sensitive to the volume fraction of constituents and the distribution of rnicrocracks in both bimodal nanostructured A1 and PAMG. Therefore, the present theoretical results can be used to optimize the microstructure for improving the mechanical properties of nanostructured Al-based composites.

关键词： Nanocomposite Mechanism Microcrack Strength Ductility

Pneumatically Actuated soft Robotic Arm for Adaptable Grasping

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Acta Mechanica Solida Sinica 2018年第5期31卷 608-622页

作者： Zhe Chen Xueya Liang Tonghao Wu Tenghao Yin Yuhai Xiang Shaoxing Qu State key laboratory of Fluid Power and Mechatronic System 38 Zheda Road Hangzhou 310027 China key laboratory of soft machines and smart devices of zhejiang province 38 Zheda Road Hangzhou 310027 China Department of Engineering Mechanics Zhejiang University 38 Zheda Road Hangzhou 310027 China

Developing robotic manipulators capable of performing effective physical interac- tion tasks is a challenging topic. In this study, we design a soft robotic arm （SRA） with multiple degrees of freedom inspired by the flexible structures and the unique motion mechanism of the octopus arm. The SRA is fabricated with elastomeric materials, which consists of four series of integrated pneumatic chambers that play similar roles as the muscles in the octopus arm can achieve large bending in various directions with variable stiffness. This SRA displays specified movements via controlling pressure and selecting channels. Moreover, utilizing parallel control, the SRA demonstrates complicated three-dimensional motions. The force response and motion of the SRA are determined both experimentally and computationally. The applications of the present SRA include tightly coiling around the objects because of its large bending deformation （nearly 360°）, grasping multiple objects, and adjusting the grabbing mode in accordance with the shape of objects.

关键词： soft robotic arm Elastomeric materials soft manipulation Variable stiffness actuation

A systematic analysis of intrinsic regulators for HIV-1 R5 to X4 phenotypic switch

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Frontiers of Electrical and Electronic Engineering in China 2017年第2期5卷 173-182页

作者： Wei Yu Yu Wu Department of Engineering Mechanics Zhejiang University Hangzhou 310027 China key laboratory of soft machines and smart devices of zhejiang province Zhejiang University Hangzhou 310027 China soft Matter Research Center Zhejiang University Hangzhou 310027 China

Background： Human immunodeficiency virus isolates most often use chemokine receptor CCR5 or CXCR4 as a coreceptor to enter target cells. During early stages of HIV-1 infection, CCR5-tropic viruses are the predominant species. The CXCR4-tropic viruses may emerge late in infection. Recognition of factors influencing this phenotypic switch may give some hints on the antiviral strategies like anti-H1V/AIDS drugs, gene therapy and vaccines. Methods： To investigate the mechanism that triggers R5 to X4 phenotypic switch, we performed a systematic sensitivity analysis based on a five-dimensional model with time-varying parameters. We studied the sensitivity of each factor to the CCR5-to-CXCR4 tropism switch and acquired some interesting outcomes beyond expectation. Results： The death rate of free virus （dv）, rate that uninfected CD4＋ T cells arise from precursors （s） and proliferate as stimulated by antigens （r）, and in vivo viral burst size （N） are four robust factors which are constantly observed to have a strong correlation with the evolution of viral phenotype for most patients longitudinally. Conclusions： Crucial factors, which are essential to phenotypie switch and disease progression, are almost the same for different patients at different time points, including the production of both virus and CD4＋ T cells and the decay of virion. It is also worth mentioning that although the sequence of factors sorted by the influence varies between patients, the trends of influences engendered by most factors as disease progresses are similar inter-patients.

关键词： HIV-1 R5-to-X4 switch two-strain model population dynamics sensitivity analysis

浙江大学智能材料与结构力学研究实验室（英文）

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Journal of zhejiang University-Science A(Applied Physics & Engineering) 2019年第4期20卷 305-310页

作者： Jian LI Chun-li ZHANG Rong-hao BAO Wei-qiu CHEN key laboratory of soft machines and smart devices of zhejiang province Department of Engineering Mechanics Zhejiang University soft Matter Research Center Zhejiang University

目的:如今新兴的智能化时代比以往任何时候都更需要性能优越的材料和结构来设计更灵活、更主动、更自动化的机器和系统,以应对越来越复杂的环境。本实验室力图探求智能材料与结构在实验或计算中观测到的力学现象(如自由振动、波传播以... 详细信息

目的:如今新兴的智能化时代比以往任何时候都更需要性能优越的材料和结构来设计更灵活、更主动、更自动化的机器和系统,以应对越来越复杂的环境。本实验室力图探求智能材料与结构在实验或计算中观测到的力学现象(如自由振动、波传播以及结构失稳等)或是多场耦合行为背后的机理,从而为先进功能设备、机械以及机器人的创新发展提供参考。最终,开发具有卓越性能的新型智能多功能器件,以满足各种实验室、工业甚至社会应用的特殊或一般要求。研究点:1.智能结构的振动与失稳分析;2.软材料的设计与制备;3.声子晶体和超材料中弹性波的调控;4.智能材料和结构中的多场耦合行为分析;5.压电、多铁性以及压电电子学器件的研发;6.多轴力/力矩智能传感器的设计。展望:虽然对智能材料和结构的研究已有近40年的历史,且其在许多现代技术和工程领域中已有了成功的应用,但是即将到来的智能化时代对"智能力学"的需求将是无穷无尽的。如果说传感器和驱动器是智能化时代的基础,那么智能材料和结构就是这些基本设备的核心。新型多功能材料的开发显然为智能材料和结构力学带来了新的生机和活力。此外,拓扑物理学等新的科学概念也将为智能材料和结构的研究开辟新的方向。本实验室将继续为基础科学、技术发展以及智能材料和结构的实际应用做出贡献。

关键词：智能材料和结构力学多场耦合智能器件智能力学

Implantable Thermal Therapeutic Device with Precise Temperature Control Enabled by Foldable Electronics and Heat-Insulating Pads

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Research 2022年第3期2022卷 297-307页

作者： Min Cai Huang Yang Liyin Shen Shuang Nie Zhengwei Mao Changyou Gao Yang Zhu Jizhou Song Department of Rehabilitation Medicine the First Affiliated Hospital College of MedicineZhejiang UniversityHangzhou 310003China Department of Engineering Mechanics Soft Matter Research Centerand Key Laboratory of Soft Machines and Smart Devices of Zhejiang ProvinceZhejiang UniversityHangzhou 310027China MOE key laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and EngineeringZhejiang UniversityHangzhou 310027China State key laboratory of Fluid Power and Mechatronic Systems Zhejiang UniversityHangzhou 310027China

Thermal therapy has continued to attract the attention of researchers and clinicians due to its important applications in tumor ablation,wound management,and drug *** lack of precise temperature control capability in traditional thermal treatment may cause the decrease of therapeutic effect and thermal damage to normal ***,we report an implantable thermal therapeutic device(ITTD),which offers precise closed loop heating,in situ temperature monitoring,and thermal *** ITTD features a multifunctional foldable electronics device wrapped on a heat-insulating composite *** and numerical studies reveal the fundamental aspects of the design,fabrication,and operation of the *** vivo experiments of the ITTD in thermal ablation for antitumor demonstrate that the proposed ITTD is capable of controlling the ablation temperature precisely in real time with a precision of at least 0.7℃ and providing effective thermal protection to normal *** proof-of-concept research creates a promising route to develop ITTD with precise temperature control capability,which is highly desired in thermal therapy and other disease diagnosis and treatments.

关键词： composite precise treatment

Modeling the Damage and Self-healing Behaviors of Plasticized PVC Gels

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Acta Mechanica Solida Sinica 2021年第4期34卷 466-476页

作者： Ninghan Tang Dong Lei Ji Lin Yanjie Wang Rui Xiao College of Mechanics and Materials Hohai UniversityNanjing211100China key laboratory of soft machines and smart devices of zhejiang province Department of Engineering MechanicsZhejiang UniversityHangzhou310027China School of Mechanical and Electrical Engineering Hohai UniversityChangzhou CampusChangzhou213022China

Plasticized polyvinyl chloride(PVC)gel is a type of electroactive polymers,which has potentials to be applied as soft ***,few studies have been performed to investigate the mechanical responses of PVC gels in cyclic loading *** this work,we combined experiments and theory to characterize the mechanical responses of two plasticized PVC *** gels were subjected to different types of loading-unloading-reloading *** experimental results showed that the plasticized PVC gels exhibited stress softening response(the Mullins effect)in the cyclic ***,the gels regained some strength after annealing at room temperature for several hours,indicating the self-healing ability of *** further extended the eight-chain model with incorporation of the chain dissociation and reassociation *** developed constitutive model is able to reproduce the Mullins effect and the recovery of the Mullins effect observed in the *** results clearly show that understanding the complex mechanical response is crucial for the applications of plasticized PVC gels.

关键词： PVC gels Mullins effect Electroactive polymers Self-healing Modeling

Electrically driven motion, destruction, and chirality change of polar vortices in oxide superlattices

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Science China(Physics,Mechanics & Astronomy) 2022年第3期65卷 77-84页

作者： Pan Chen Congbing Tan Zhexin Jiang Peng Gao Yuanwei Sun Lifen Wang Xiaomei Li Ruixue Zhu Lei Liao Xu Hou Ke Qu Ning Li Xiaomin Li Zhi Xu Kaihui Liu Wenlong Wang Jinbin Wang Xiaoping Ouyang Xiangli Zhong Jie Wang Xuedong Bai Beijing National laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China International Center for Quantum Materials Electron Microscopy LaboratorySchool of PhysicsPeking UniversityBeijing 100871China Hunan Provincial key laboratory of Intelligent Sensors and Advanced Sensor Materials School of Physics and ElectronicsHunan University of Science and TechnologyXiangtan 411201China Department of Engineering Mechanics Zhejiang UniversityHangzhou 310027China Collaborative Innovation Center of Quantum Matter Beijing 100871China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100190China Songshan Lake Materials laboratory Dongguan 523808China State key laboratory for Artificial Microstructure&Mesoscopic Physics School of PhysicsPeking UniversityBeijing 100871China School of Materials Science and Engineering Xiangtan UniversityXiangtan 411105China key laboratory of soft machines and smart devices of zhejiang province Zhejiang UniversityHangzhou 310027China

Topological polar vortices, which are electric analogs of magnetic objects, present great potential in applications of future nanoelectronics because of their nanometer size, anomalous dielectric response, and chirality. To enable the functionalities, it is prerequisite to manipulate the polar states and chirality by using external stimuli. Here, we probe the evolutions of polar state and chirality evolutions of topological polar vortices in Pb TiO;/Sr TiO;superlattices under an electric field by using atomically resolved in situ scanning transmission electron microscopy and phase-field simulations. We find that, under electric field, the chiral vortex cores can be moved laterally to form close-pair structures, transform into a/c domain stripes, and finally become a nonchiral c-domain. Such transition is reversible and spontaneous after bias removal. Interestingly, during switching and backswitching events, the vortex rotation can be changed, offering a potential strategy to manipulate vortex chirality. The revealed dynamic behavior of individual polar vortices at the atomic scale provides fundamentals for future device applications.

关键词： chirality polar vortex ferroelectrics in situ transmission electron microscopy phase-field simulations

Preface to the"soft Matter Mechanics"Special Issue of Acta Mechanica Solida Sinica

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Acta Mechanica Solida Sinica 2019年第5期32卷 533-534页

作者： Jin Qian Tongqing Lu Shaoxing Qu key laboratory of soft machines and smart devices of zhejiang province Department of Engineering MechanicsZhejiang UniversityHangzhou 310027China State key Lab for Strength and Vibration of Mechanical Structures Department of Engineering MechanicsXi'an Jiaotong UniversityXi'an 710049China

Different from ordinary solids,liquids and gases,soft matter is a subfield of condensed matter comprising a complexity of physical states and softness that are easily modulated by external stimuli and/or thermal flue tu at ions,with the featured sensitivity to tiny perturbations from the *** soft matter research is considered to be“the science of the 21st century,”which is rapidly evolving and growing at the interfaces of mechanics,physics,biology,material science,chemistry,etc.

关键词： environment. solids gases