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串联2-2型压电复合材料结构较为简单,它是研究具有复杂连通性压电复合材料的基础。本文从能量的角度推导出串联2-2复合材料中压电陶瓷层上的电场强度Ec=εpVcεp+εc(1-Vc)Eo和聚合物层上的电场强度Ep=εcVcεp+εc(1-Vc)Eo。由于压电陶瓷的介电常数εc(≈1600ε0)远远大于聚合物的介电常数εp(≈12ε0),因此Ep远远大于Ec。尽管聚合物的介电强度高于压电陶瓷的介电强度,但由于Ep远远大于Ec,所以串联2-2型压电复合材料的介电击穿往往是从聚合物层开始的,最后导致复合材料整体被击穿。 相似文献
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利用厚度剪切压电效应的2—2型压电复合材料的性能研究 总被引:3,自引:1,他引:2
制备了利用厚度剪切压电效应的22型压电复合材料,测试了在电场作用下压电复合材料的变形特性,初步研究了不同参数对压电复合材料变形性能的影响。结果表明:(1)由于柔性聚合物的加入,压电复合材料的变形性能得到了大幅度的提高;(2)随着PZT体积份数的增大,压电复合材料的变形量增大,直至达到最大,随后则随着PZT体积份数的增大而下降;(3)PZT单元的尺寸越小,压电复合材料的变形量越大。 相似文献
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陶瓷/聚合物压电复合材料的国内外概况和应用展望 总被引:5,自引:0,他引:5
引言 压电材料是指材料在外力作用下产生电流,或反过来在电流作用下产生力或形变的一种功能材料。压电复合材料是70年代发展起来的一类功能复合材料,一般是由压电陶瓷和聚合物基体按照一定的连接方式、一定的体积或质量比例和一定的空间几何分布复合而成。由于这种复合材料兼有组成复合材料各组分的性能,因而某些性能将得到大幅度的提高。传统的压电陶瓷PZT(锆钛酸铅),PT(钛酸铅)等,由于密度高、声阻抗大、性脆,不能制成大面积薄片和复杂的形状,还有不易与水和人体等轻质负载匹配的缺点。而压电聚合物如PVDF具有密度低、柔性好、阻抗低,易与轻质负载匹配的特性,但缺点在于压电常数低,有强的各向异性以及极化困难等。压电复合材料则克服了两者的不 相似文献
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通过MATLAB软件对陶瓷颗粒均匀分布的0-3型压电陶瓷/聚合物复合材料进行了建模, 通过有限元分析软件ANSYS, 研究了压电复合材料受力时内部应力分布及电荷分布状态, 同时研究了压电陶瓷颗粒体积分数及静态载荷变化时, 压电陶瓷/聚合物复合材料中压电陶瓷产生的最大节点电压的变化情况。研究表明: 压电陶瓷/聚合物复合材料在受力时, 压电相受到的应力远远大于聚合物相, 压电相棱角处受到的应力最大, 产生的电荷最多。随着压电陶瓷体积分数变化, 压电复合材料中压电陶瓷产生的最大节点电压也增加, 当压电陶瓷体积分数达到30%时, 产生的最大节点电压达到2.86×10-5 V。随着静态载荷的增加, 压电复合材料产生的最大节点电压呈线性增加, 阻尼效果越明显, 与文献中的实验结果吻合。 相似文献
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通过MATLAB软件对陶瓷颗粒均匀分布的0-3型压电陶瓷/聚合物复合材料进行了建模,通过有限元分析软件ANSYS,研究了压电复合材料受力时内部应力分布及电荷分布状态,同时研究了压电陶瓷颗粒体积分数及静态载荷变化时,压电陶瓷/聚合物复合材料中压电陶瓷产生的最大节点电压的变化情况.研究表明:压电陶瓷/聚合物复合材料在受力时,压电相受到的应力远远大于聚合物相,压电相棱角处受到的应力最大,产生的电荷最多.随着压电陶瓷体积分数变化,压电复合材料中压电陶瓷产生的最大节点电压也增加,当压电陶瓷体积分数达到30%时,产生的最大节点电压达到2.86×10-5V.随着静态载荷的增加,压电复合材料产生的最大节点电压呈线性增加,阻尼效果越明显,与文献中的实验结果吻合. 相似文献
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《International journal for numerical methods in engineering》2018,113(9):1488-1506
In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method. 相似文献
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A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa. 相似文献
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On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.…… 相似文献
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Standards are the basis for production enterprises to organize production ex-factory inspection trade 《中国标准化(英文版)》2008,25(1):24-25
Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.…… 相似文献
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A four-ball tester was used to evaluate the anti-wear performance of three kinds of organomolybdemun compounds in the engine oils, i. e., molybdenum dialkyldithiophosphate (MoDDP), molybdenum dialkyldithiocarbamate ( MoDTC), and sulphur and phosphorus freeorganomolybdeum (Molybdate). The results indicate that a low concentration of MoDDP doesn' t improve the anti-wear properties of the commercial engine oils, but a high concentration of MoDDP can obviously improve the anti-wear properties and the load-carrying capacity of the engine oils. MoDTC doesn' t improve the antiwear properties of the engine oils, but worsens the anti-wear properties of the oils. Signifi can timprove ment of frictional and wear characteristics is obtained with Molybdate added in the commercial engine oils and the formulated oils. 相似文献
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C. Qihong W. Zhan‐Wen J. Yi J. Yehua L. Fei F. Hanguang 《Materialwissenschaft und Werkstofftechnik》2014,45(7):582-590
In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M2(B,C), (W,Mo)2(B,C), M3(B,C), M23(B,C)6 type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm2. The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K1 mill housing of bar mill. 相似文献
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Steffen Müller-Probandt 《材料科学与工程:中英文B版...》2018,(4):161-177
We associate a variety of innovations with the term "Industry 4.0". The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di... 相似文献
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Dimiter Hadjistamov 《材料科学与工程:中英文B版...》2019,(2):56-65
The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ... 相似文献
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Kyo-Hong CHOI Kwon-Koo CHO Gyu-Bong CHO Hyo-Jun AHN Ki-Won KIM Yoo-Young KIM 《材料科学与工程学报》2007,25(6):886-891
Several researches have been reported about the characteristic of β-Ga2O3 nanowires which was synthesized on nickel oxide particle. But indeed, recent researches about synthesis of β-Ga2O3 nanowires on oxide-assisted transition metal are limited to nickel or cobalt oxide catalyst. In this work, Gallium oxide (β-Ga2O3 ) nanowires were synthesized by a simple thermal evaporation method from gallium powder in the range of 700 - 1000℃ using the iron, nickel, copper, cobalt and zinc oxide as a catalyst, respectively. The β-Ga2O3 nanowires with single crystalline without defects were successfully synthesized at the reaction temperature of 850, 900 and 950℃ in all the catalysts. But optimum experimental condition in synthesis of nanowires varied with the kind of catalyst. As increasing synthesis temperature,the morphology of gallium oxide nanowires changed from nanowires to nanorods, and its diameter increased. From these results, we could be proposed that the growth mechanism of β-Ga2O3 nanowires was changed with synthesis temperature of nanowires. Microstructure and morphology of Synthesized nanowire was characterized by HR-TEM, FE-SEM, EDX and XRD. 相似文献