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The in-plane Orientation and Thermal Mechanical Properties of the Chemically Imidized Polyimide Films

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Chinese Journal of Polymer Science 2019年第3期37卷 268-278页

作者： Zhen-He Wang Xing Chen Hai-Xia Yang Jiang Zhao Shi-Yong Yang Laboratory of Advanced Polymer Materials Institute of Chemistry Chinese Academy of Sciences University of Chinese Academy of Science State Key Laboratory of Polymer Physics and Chemistry Institute of Chemistry Chinese Academy of Sciences Department of Polymer Science The University of Akron

The thermal and mechanical properties of the chemically imidized polyimide(CIPI) films and thermally imidized polyimide(TIPI) films were investigated systematically. Experimental results indicated that the CIPI films show dramatically enhanced tensile strength and modulus with obviously reduced coefficient of thermal expansion(CTE) in comparison with TIPI films. These enhancements results from the high in-plane orientation and close packing of the CIPI backbones. Compared with thermal imidization which starts at about 140 °C, the chemical imidization activated by acetic anhydride and isoquinoline initiates the cyclization even at room *** resulting imide rings restrict the mobility of polymer chains and lead to the in-plane orientation with solvent ***, fewer small molecules remain in the films after treated at 120 °C by chemical imidization than by thermal imidization. The polymer chain plasticization caused by the evaporation of small molecules at high temperature is obviously restricted. Moreover, the partially imidized polymer inhibits the decomposition of mainchains that occurs at subsequent high temperature process, being beneficial to the formation of high molecular weight PI films. Hence, chemical imidization pathway shows apparent advantage to produce PI films with great combined properties, including high modulus, strength and toughness, as well as high thermal dimension stability etc.

关键词： Polyimide film Chemical imidization Thermal imidization in-plane orientation CTE

The Failure Mechanisms of Ultra-high Molecular Weight Polyethylene Fibre Composites Under in-plane Compression

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Journal of Wuhan University of Technology(Materials Science) 2020年第1期35卷 240-247页

作者：刘国亮张玉武 College of Textile and Clothing Yancheng Institute of TechnologyYancheng 224051China Faculty of Engineering University of NottinghamNottingham NG72RDUnited Kingdom College of Liberal Arts and Sciences National Unversity of Defense TechnologyChangsha 410073China

The in-plane compressive characteristics of the ultra-high molecular weight polyethylene(UHMWPE)fibre(Dyneema█)reinforced composites,both in 0/90°and±45°fibre orientations with respect to the loading direction,have been *** composite made from unidirectional high modulus fibres(volume fraction 83%)and low strength polyurethane matrix(volume fraction 17%)is layered in an orthogonally alternating *** different failure mechanisms for the composites with 0/90°and±45°fibre orientations have been detected with the methods of experimental measurement,SEM observation and theoretical *** composites specimens of 0/90°fibre orientation failed with macro-buckling of the high-modulus UHMWEP fibre layers with the matrix damage,whereas the specimens of±45°fibre orientation failed with the shearing of the soft ***,the composite specimens in 0/90°fibre orientation had higher stiffness as well as compressive strength than those in±45°fibre *** failure criteria of the composites under in-plane compression was employed to characterize the failure *** with the traditional thermoset matrix,the soft thermoplastic matrix leads to lower strength and higher failure strain of fibre reinforced composites under in-plane *** addition,the composite specimens cut by waterjet machine exhibited higher stress levels than those cut by bandsaw that introduced more initial imperfections with the temperature rising and tensile *** comparison between the methodologies for cutting the tough composites can provide a valuable suggestion to obtain required composite structures without reducing the mechanical properties.

关键词： UHMWPE fibre composites in-plane compression failure mechanisms fibre buckling matrix shearing

Recent advances and key opportunities on in-plane micro-supercapacitors:From functional microdevices to smart integrated microsystems

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Journal of Energy Chemistry 2023年第6期81卷 410-431,I0010页

作者： Jieqiong Qin Hongtao Zhang Zhi Yang Xiao Wang Pratteek Das Feng Zhou Zhong-Shuai Wu State Key Laboratory of Catalysis Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023LiaoningChina College of Science Henan Agricultural UniversityZhengzhou 450002HenanChina Dalian National Laboratory for Clean Energy Chinese Academy of SciencesDalian 116023LiaoningChina

The popularization of portable,implantable and wearable microelectronics has greatly stimulated the rapid development of high-power planar micro-supercapacitors(PMSCs).Particularly,the introduction of new functionalities(e.g.,high voltage,flexibility,stretchability,self-healing,electrochromism and photo/thermal response)to PMSCs is essential for building multifunctional PMSCs and their smart selfpowered integrated *** this review,we summarized the latest advances in PMSCs from various functional microdevices to their smart integrated ***,the functionalities of PMSCs are characterized by three major factors to emphasize their electrochemical behavior and unique scope of *** include but are not limited to high-voltage outputs(realized through asymmetric configuration,novel electrolyte and modular integration),mechanical resilience that includes various feats of flexibility or stretchability,and response to stimuli(self-healing,electrochromic,photo-responsive,or thermal-responsive properties).Furthermore,three representative integrated microsystems including energy harvester-PMSC,PMSC-energy consumption,and all-in-one selfpowered microsystems are elaborately overviewed to understand the emerging intelligent interaction ***,the key perspectives,challenges and opportunities of PMSCs for powering smart microelectronics are proposed in brief.

关键词： Micro-supercapacitors in-plane Functionalization Integrated microsystem Energy storage

Dynamic in-plane transversal normal stresses in the concrete face of CFRD

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Frontiers of Structural and Civil Engineering 2019年第1期13卷 135-148页

作者： Neftali SARMIENTO-SOLANO Miguel P.ROMO Institute of Engineering National University of MexicoMexico City04510Mexico

Severe earthquakes can induce damages to Concrete Face Rocldill Dams (CFRDs)such as concrete cracking and joint's water stops distressing where high in-plane transversal normal stresses *** these damages rarely jeopardize the dam safety,they cause large water reservoir leakages that hinder the dam *** issue can be addressed using well know numerical methods;however,given the wide range of parameters involved,it would seem appropriate to develop a simple yet reliable procedure to get a close understanding how their interaction affects the CFRD's overall ***,once the physics of the problem is better understood one can proceed to perform a detailed design of the various components of the *** this end an easy-to-use procedure that accounts for the dam height effects,valley narrowness,valley slopes,width of concrete slabs and seismic excitation characteristics was *** procedure is the dynamic complement of a method recently developed to evaluate in-plane transversal normal stresses in the concrete face of CFRD's due to dam reservoir filling [1].Using these two procedures in a sequential manner,it is possible to define the concrete slab in-plane normal stresses induced by the reservoir filling and the action of orthogonal horizontal seismic excitations acting at the same time upstream-downstream and cross *** procedures were developed from a data base generated using nonlinear static and dynamic three-dimensional numerical analyses on the same group of CFRD'***,the results were interpreted with the Buckingham Pi theorem and various relationships were *** the above reference,the method to evaluate the concrete face in-plane transversal normal stresses caused by the first reservoir filling was *** this paper,the seismic procedure is first developed and then through an example the whole method (dam construction,reservoir filling plus seismic loading)of analysis is assessed.

关键词： CFR dams dynamic analysis in-plane normal stresses concrete face

Out-of-plane and in-plane piezoelectric behaviors of [Ba(Zr0.2Ti0.8)O3]–0.5(Ba0.7Ca0.3TiO3) thin films

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Progress in Natural Science:Materials International 2017年第6期27卷 664-668页

作者： Zhi Tao Fei Che Yemei Han Fang Wang Zhengchun Yang Wen Qi Ying Wu Kailiang Zhang School of Electronic and Information Engineering Tianjin Key Laboratory of Film Electronic & Communication Devices Tianjin University of Technology Beijing Key Laboratory of Energy Nanomaterials Advance Technology & Materials Co Ltd. China Iron & Steel Research Institute Group

The piezoelectric properties of [Ba(Zr;Ti;)O;]–0.5(Ba;Ca;TiO;)（abbreviated as BZT-0.5BCT） thin films deposited on Pt/Ti/SiO;/Si substrates are reported in the present investigation. The effect of the distances between the target and substrate（d） on the morphology and out-of-plane piezoelectric properties was *** experimental results showed that the ferroelectric domains size was dependent on the distance between the substrate and target and the ferroelectric domain growth was constrained by the grains. The samples exhibited well-defined out-of-plane butterfly loops and hysteresis loops and the one with d of 6.5 cm possessed the optimal ferroelectric properties and it exhibited good in-plane piezoelectric properties.

关键词： Piezoelectrics BZT-BCT Ferroelectric domains Out-of-plane in-plane

Determination of the in-plane anisotropy field in hexagonal systems via rotational magnetization: Theoretical model and Monte Carlo simulations

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Science China(Physics,Mechanics & Astronomy) 2009年第7期52卷 978-986页

作者： WANG AiMin PANG Hua Institute of Applied Magnetics Key Laboratory for Magnetism and Magnetic Materials of the Ministry of EducationLanzhou UniversityLanzhou 730000China

The magnetic anisotropy field in thin films with in-plane uniaxial anisotropy can be deduced from the VSM magnetization curves measured in magnetic fields of constant magnitudes. This offers a new possibility of applying rotational magnetization curves to determine the firstand second-order anisotropy constant in these films. In this paper we report a theoretical derivation of rotational magnetization curve in hexagonal crystal system with easy-plane anisotropy based on the principle of the minimum total energy. This model is applied to calculate and analyze the rotational magnetization process for magnetic spherical particles with hexagonal easy-plane anisotropy when rotating the external magnetic field in the basal plane. The theoretical calculations are consistent with Monte Carlo simulation results. It is found that to well reproduce experimental curves, the effect of coercive force on the magnetization reversal process should be fully considered when the intensity of the external field is much weaker than that of the anisotropy field. Our research proves that the rotational magnetization curve from VSM measurement provides an effective access to analyze the in-plane anisotropy constant K3 in hexagonal compounds, and the suitable experimental condition to measure K3 is met when the ratio of the magnitude of the external field to that of the anisotropy field is around 0.2.

关键词： rotational magnetization curve magnetocrystalline anisotropy in-plane anisotropy constant K3

Effects of Cell Microtopology on the in-plane Dynamic Crushing Analysis of Re-entrant Square Cellular Material

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Automotive Innovation 2018年第1期1卷 24-34页

作者： Fangwu Ma Ying Zhao Hongyu Liang Jiawei Wang State Key Laboratory of Automotive Simulation and Control Jilin UniversityChangchun 130025China Department of Mechanical Engineering University of MichiganAnn ArborMI 48109-2102USA

With the development of three-dimensional printing technologies, so-called cellular materials have achieved increasingattention due to outstanding properties. Unlike pure solid structures, properties of cellular materials are influenced by bothutilized material and cell microtopology. The present paper proposes a novel type of re-entrant square cellular *** explore the relationship between microtopology and macrodynamic responses systematically, an explicit dynamic finiteelement simulation method is used. This work starts by constructing theoretical models of relative density employing atwo-dimensional unit cell. Then, the effects of geometric features and configurations on dynamic properties are explored,and simulations indicate that variations of geometric parameters strongly affect properties and that the staggered re-entrantsquares are more stable than the regular re-entrant squares. Subsequently, the effects of the impact velocity on dynamiccrushing behaviors are elaborated. On this basis, the relationship of unit mass energy absorption and geometric features isobtained by employing the response surface method. Furthermore, with targets of maximum unit mass energy absorption andminimum relative density, the optimal structural parameters are achieved by using non-dominated sorting genetic *** study provides a detailed introduction to dynamic behaviors of cellular materials and guidance to design new structureswith superior characteristics of energy absorption.

关键词： Re-entrant cellular material Dynamic crushing Microtopology in-plane Finite element analysis

Amplification of in-plane seismic ground motion by group cavities in layered half-space (Ⅰ)

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Earthquake Science 2012年第4期25卷 275-285页

作者： Jianwen Liang Ji Zhang Zhenning Ba Department of Civil Engineering Tianjin University Tianjin Key Laboratory of Civil Engineering Structures and New Materials

Amplification of in-plane seismic ground motion by underground group cavities in layered half-space is studied both in frequency domain and time domain by using indirect boundary element method （IBEM）, and the effect of cavity interval and spectrum of incident waves on the amplification are studied by numerical examples. It is shown that there may be large interaction between cavities, and group cavities with certain intervals may have significant amplification to seismic ground motion. The amplification of PGA （peak ground acceleration） and its PRS （peak response spectrum） can be increased up to 45.2% and 84.4%, for an example site in Tianjin, under the excitation of Taft wave and E1 Centro wave; and group cavities may also affect the spectra of the seismic ground motion. It is suggested that the effect of underground group cavities on design seismic ground motion should be considered.

关键词： underground group cavity amplification in-plane seismic ground motion time domain frequency domain indirect boundary element method (IBEM)

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in-plane attenuation zone and its optimization in a plate with periodic holes

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Chinese Journal of Acoustics 2019年第1期38卷 85-98页

作者： LIU Xiongwei HUANG Jiankun HU Yucun LI Yaguang LIU Wen Department of Civil Engineering School of Soil and Water ConservationBeijing Forestry University

It is difficult to design a plate with wide attenuation zones in low frequency region based on Bragg scattering mechanism. A plate with periodic rhombic holes is optimized and designed. Based on the finite element method under periodic boundary conditions, the in-plane dispersion curves of periodically perforated plate are calculated via COMSOL. The frequency responses of periodically perforated plate axe investigated via ANSYS simulation. The plates with periodic holes are suspended and dynamically tested under sinusoidal excitations. The results show that a periodically perforated plate with rhombus holes has wider attenuation zones than plates with circular and hexagonal holes. Material properties have a great influence on attenuation zones: nitrile-butadiene rubber and silicon rubber can easily obtain low-frequency zones, while increasing porosity creates lower and wider zones. The width of attenuation zone increases as the horizontal angle of the rhombus holes increases. An analysis of the attenuation zones* generation mechanism shows that the plate with periodic holes exhibits characteristics of Bragg scattering and local resonant phononic crystal, indicating an inherent relationship between two types of mechanisms. The optimized plate has a complete attenuation zone ranging from 5281.76-8824.30 Hz. The vibrations are significantly reduced when the number of periods is no less than two. The attenuation range obtained via the numerical method is generally consistent with the experiment. The research sheds light on the noise insulation plate and has the potential to improve the sound environment in various applications due to its simple manufacturing.

关键词： in-plane attenuation zone plate with periodic holes COMSOL