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Suspension printing of liquid metal in yield-stress fluid for resilient 3D constructs with electromagnetic functions

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npj Flexible Electronics 2022年第1期6卷 507-517页

作者： Qian Wu Fengbo Zhu Ziliang Wu Yu Xie Jin Qian Jun Yin Huayong Yang The State key laboratory of Fluid Power and Mechatronic Systems School of Mechanical EngineeringZhejiang UniversityHangzhou 310028China key laboratory of 3D Printing Process and Equipment of zhejiang province School of Mechanical EngineeringZhejiang UniversityHangzhou 310028China College of Materials Science&Engineering Taiyuan University of TechnologyTaiyuan 030024China MOE key laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and EngineeringZhejiang UniversityHangzhou 310027China key laboratory of soft machines and smart devices of zhejiang province Department of Engineering MechanicsZhejiang UniversityHangzhou 310027China

Liquid metal is an ideal conductive material for soft electronics because of its high conductivity and fluidity at room temperature.However,the large surface tension and high mass density of liquid metal make forming three-dimensional(3D)dangling structures a challenging task.Reported here is a suspension printing strategy for direct deposition of galinstan-based liquid metal into 3D dangling structures with high shape fidelity and spatial resolution(~150μm).Acrylamide/nanoclay suspension served as a yieldstress fluid support bath,with selected hydrogen peroxide to immediately oxidize the gallium skin and strengthen the extruded liquid metal,thus continuous liquid metal filaments were deposited successfully.The subsequent photo-curing of acrylamide/nanoclay works as a resilient outer packaging,giving rise to a~500%tensile deformation for liquid metal-hydrogel composite.This suspension printing strategy should broaden the opportunity of using 3D and functional liquid metal constructs for soft yet resilient electromagnetic devices.

关键词： stress deformation liquid

Effect of negative permeability on elastic wave propagation in magnetoelastic multilayered composites

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Theoretical & Applied Mechanics Letters 2017年第3期7卷 126-133页

作者： W. Wang Y.Q. Guo W.Q. Chen key laboratory of Mechanics on Disaster and Environment in Western China Ministry of Education and School of Civil Engineering and MechanicsLanzhou University Lanzhou 730000 China Department of Engineering Mechanics Yuquan Campus Zhejiang University Hangzhou 310027 China key laboratory of soft machines and smart devices of zhejiang province Zhejiang University Hangzhou 310027 China

With the advent of left-handed magnetic materials, it is desirable to develop high-performance wave devices based on their novel properties of wave propagation. This letter reports the special properties of elastic wave propagation in magnetoelastic multilayered composites with negative permeability as compared to those in counterpart structures with positive permeability. These novel properties of elastic waves are discerned from the diversified dispersion curves, which represent the propagation and attenuation characteristics of elastic waves. To compute these dispersion curves, the method of reverberation-ray matrix is extended for the analysis of elastic waves in magnetoelastic multilayered composites. Although only the results of a single piezomagnetic and a binary magnetoelastic layers with mechanically free and magnetically short surfaces as well as perfect interface are illustrated in the numerical examples, the analysis is applicable to magnetoelastic multilayered structures with other kinds of boundaries/interfaces.

关键词： Magnetoelastic multilayered composites Elastic wave propagation Method of reverberation-ray matrix Negative permeability Wave mode conversion

Preface:Mechanics of soft materials and lexible structures

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Acta Mechanica Sinica 2021年第5期37卷 746-747页

作者： Haibao Lu Shaoxing Qu Xiqiao Feng State key laboratory of Science and Technology On Advanced Composites in Special Environments Harbin Institute of TechnologyHarbin 150080P.R.China key laboratory of soft machines and smart devices of zhejiang province Department of Engineering MechanicsZhejiang UniversityHangzhou 310027China Institute of Biomechanics and Medical Engineering AMLDepartment of Engineering MechanicsTsinghua UniversityBeijing 100084China

soft materials and lexible structures have become essential and hot topic,which is expected to signiicantly promote the research and development of current mechanics,physics,chemistry and life science.Furthermore,the soft materials and lexible structures have attracted enthusiastic attentions due to their great potential and practical applications in deployable structures,morphing structures,sensors,actuators,health-monitoring etc.

关键词： Mechanics structures Preface

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Topological prime

Science China(Technological Sciences) 2020年第7期63卷 1314-1322页

作者： YANG XuXu YANG CanHui LIU JunJie YAO Xi SUO ZhiGang John A.Paulson School of Engineering and Applied Sciences Kavli Institute for Bionano Science and TechnologyHarvard UniversityCambridge MA 02138USA State key laboratory of Fluid Power&Mechatronic System Key Laboratory of Soft Machines and Smart Devices of Zhejiang ProvinceDepartment of Engineering Mechanics and Center for X-MechanicsZhejiang UniversityHangzhou 310027China Department of Mechanics and Aerospace Engineering Southern University of Science and TechnologyShenzhen 518055China key Lab for Special Functional Materials of Ministry of Education Henan UniversityKaifeng 475004China

This paper describes a general method, called topological prime, to stitch functional groups to a substrate of entropic polymer network. The precursor of a topological primer contains polymers, crosslinkers, and coupling agents. When the precursor is applied on the surface of the substrate, the crosslinkers link the primer polymers into a primer network, in topological entanglement with the substrate network, while the coupling agents link the primer network to the functional groups. The use of topological prime is demonstrated by priming a hydrophobic elastomer of an arbitrary shape for hydrophilic coating. We describe an approach that fulfills two fundamental requirements: wetting and adhesion. The coated elastomer maintains hydrophilicity and lubricity after stretch, scratch, swell, and slide. As a further demonstration, a hydrogel substrate is primed for hydrophobic coating. Topological prime opens an enormous space for applications in engineering and biomedicine.

关键词： elastomer hydrogel hydrophilic coating topological prime functional groups

Acarid Suction Cup-Inspired Rapid and Tunable Magnetic Adhesion

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Acarid Suction Cup-Inspired Rapid and Tunable Magnetic Adhes...

压电半导体杆中的机械场、电场与载流子分布研究（英文）

中国力学大会-2021+1

作者： Xiaocheng Hu Yimou Fu Yide Liu Binhong Liu Shaoxing Qu NC State key laboratory of Fluid Power and Mechatronic System key laboratory of soft machines and smart devices of zhejiang province Center for X-Mechanics Department of Engineering Mechanics zhejiang University

ED Adhesion appears in nature as a kind of clinging strategy for living creatures to survive in a complex environment.Nevertheless,the artificial counterpart applications are limited by many factors,such as slow responding rate and high driving voltage.In this paper,a novel magnetic adhesion achieved by the actuation of Ecoflex embedded with iron particles is presented,

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Journal of zhejiang University-Science A(Applied Physics & Engineering) 2016年第1期17卷 37-44页

作者： Chun-li ZHANG Xiao-yuan WANG Wei-qiu CHEN Jia-shi YANG Department of Engineering Mechanics zhejiang University Hangzhou 310027 China Department of Mechanical and Materials Engineering University of Nebraska-Lincoln Lincoln NE 68588-0526 USA soft Matter Research Center Zhejiang University Hangzhou 310027 China key laboratory of soft machines and smart devices of zhejiang province Hangzhou 310027 China

目的:导出两端自由压电半导体杆在自平衡状态下内部的位移、电场和载流子的解析表达式,研究它们在杆内的分布规律。方法:从三维压电半导体基本方程出发,以n-型半导体为例,导出考虑拉伸变形模式的一维模型方程。由平衡方程和电学高斯方... 详细信息

目的:导出两端自由压电半导体杆在自平衡状态下内部的位移、电场和载流子的解析表达式,研究它们在杆内的分布规律。方法:从三维压电半导体基本方程出发,以n-型半导体为例,导出考虑拉伸变形模式的一维模型方程。由平衡方程和电学高斯方程和平衡态下杆内电流为零的条件得到以电场为未知函数一阶非线性偏微分方程,再利用两端自由的边界条件解出位移、电场和载流子的分布函数。结论:压电半导体杆内位移、载流子和电势关于杆的几何中心对称分布,电场、应变则关于中心呈反对称分布形式;它们在半导体两端部的区域变化比在中心区域的变化剧烈。此外,半导体杆两端部的载流子浓度、位移和电场显著依赖于端部的初始载流子浓度。

关键词：力电耦合半导体杆载流子

Effects of surface charges on phonon properties and thermal conductivity in GaN nanofilms

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Chinese Physics B 2019年第8期28卷 270-275页

作者：杨树森侯阳朱林利 Department of Engineering Mechanics and Key Laboratory of Soft Machines and Smart Devices of Zhejiang ProvinceZhejiang UniversityHangzhou 310021China School of Naval Architecture and Ocean Engineering Jiangsu University of Science and TechnologyZhenjiang 212000China

Surface charges can modify the elastic modulus of nanostructure,leading to the change of the phonon and thermal properties in semiconductor nanostructure.In this work,the influence of surface charges on the phonon properties and phonon thermal conductivity of GaN nanofilm are quantitatively investigated.In the framework of continuum mechanics,the modified elastic modulus can be derived for the nanofilm with surface charges.The elastic model is presented to analyze the phonon properties such as the phonon dispersion relation,phonon group velocity,density of states of phonons in nanofilm with the surface charges.The phonon thermal conductivity of nanofilm can be obtained by considering surface charges.The simulation results demonstrate that surface charges can significantly change the phonon properties and thermal conductivity in a GaN nanofilm.Positive surface charges reduce the phonon energy and phonon group velocity but increase the density of states of phonons.The surface charges can change the size and temperature dependence of phonon thermal conductivity of GaN nanofilm.Based on these theoretical results,one can adjust the phonon properties and temperature/size dependent thermal conductivity in GaN nanofilm by changing the surface charges.

关键词： surface charges GaN nanofilm elastic model phonon properties thermal conductivity

Electrocaloric effect in ferroelectric materials:From phase field to first-principles based effective Hamiltonian modeling

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Materials Reports(Energy) 2021年第3期1卷 34-63页

作者： Jingtong Zhang Xu Hou Yajun Zhang Gang Tang Jie Wang Department of Engineering Mechanics School of Aeronautics and AstronauticsZhejiang UniversityHangzhou310027PR China Department of Mechanics and Engineering Sciences College of Civil Engineering and MechanicsLanzhou UniversityLanzhouGansu730000PR China Theoretical Materials Physics Q-MATCESAMUniversity of LiegeB-4000LiegeBelgium key laboratory of soft machines and smart devices of zhejiang province Zhejiang UniversityHangzhou310027PR China

Electrocaloric effect(ECE)of ferroelectrics has attracted considerable interest due to its potential application in environmentally friendly solid-state refrigeration.The discovery of giant ECE in ferroelectric thin films has greatly renewed the research activities and significantly stimulated experimental and theoretical investigations.In this review,the recent progress on the theoretical modeling of ECE in ferroelectric and antiferroelectric materials are introduced,which mainly focuses on the phase field modeling and first-principles based effective Hamiltonian method.We firstly provide the theoretical foundation and technique details for each method.Then a comprehensive review on the progress in the application of two methods and the strategies to tune the ECE are presented.Finally,we outline the practical procedure on the development of multi-scale computational method without experiemtal parameters for the screening of optimized electrocaloric materials.

关键词： Electrocaloric effect Ferroelectric materials Phase field simulation Machine learning models First-principles based effective Hamiltonian modeling

带隙可调的超结构梁：数值和实验研究（英文）

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Journal of zhejiang University-Science A(Applied Physics & Engineering) 2019年第11期20卷 811-822页

作者： Yi YUAN Wei-jian ZHOU Jian LI Wei-qiu CHEN Rong-hao BAO key laboratory of soft machines and smart devices of zhejiang province&Department of Engineering Mechanics Zhejiang UniversityHangzhou 310027China Department of Architecture and Civil Engineering City University of Hong KongHong KongChina State key Lab of CAD&CG Zhejiang UniversityHangzhou 310058China soft Matter Research Center Zhejiang UniversityHangzhou 310027China

目的:1.研究晶格常数、预应力和弹簧刚度对超结构梁带隙的影响,优化结构并形成伪禁带或低频且宽的禁带;2.通过实验验证伪禁带的存在性、排列对带隙的影响以及缺陷对带隙的影响等。创新点:1.通过预应力调节超结构梁的带隙特征,并可以形... 详细信息

目的:1.研究晶格常数、预应力和弹簧刚度对超结构梁带隙的影响,优化结构并形成伪禁带或低频且宽的禁带;2.通过实验验证伪禁带的存在性、排列对带隙的影响以及缺陷对带隙的影响等。创新点:1.通过预应力调节超结构梁的带隙特征,并可以形成伪禁带;2.通过排列不同弹簧振子构成宽频禁带和宽频伪禁带。方法:1.通过有限元软件模拟预应力、弹簧刚度和晶格常数等参数对该超结构梁带隙的影响情况;2.设计合适的参数并进行结构优化,使得该结构的带隙宽,频率低,且易于实验实现;3.在实验中通过替换弹簧、改变弹簧间距和施加轴向拉力分别研究弹簧刚度、晶格常数和预应力的影响,并通过移除部分弹簧和同时布置不同弹簧的方式研究缺陷和排列对带隙的影响。结论:1.该结构存在一条局域共振禁带和多条布拉格散射禁带;通过调节预应力、弹簧刚度和晶格常数等可以有效地控制带隙特征。2.在特定条件下可以形成宽频伪禁带;通过排列不同弹簧振子可以达到拓宽禁带、形成宽频伪禁带的效果。3.缺陷对布拉格散射禁带的影响较大,对局域共振禁带的影响较小。

关键词：超结构梁预拉伸可调带隙伪禁带排列