IPN压电阻尼材料的研究进展

阻尼材料广泛应用于交通工具、产业机械、建筑土木、家用电器、精密仪器和军事装备等领域。科学技术的不断发展,对阻尼材料的要求不断提高。本文主要综述了阻尼材料的发展状况,阐述了粘弹性阻尼、高阻尼合金、阻尼复合以及聚合物基压电智能阻尼材料的阻尼机理,并详细分析介绍了聚合物基IPN压电阻尼材料的设计原理及阻尼效果。     

基于无线传感器网络的压电能量收集技术

随着物联网的发展,多节点的传感器供电成为关键问题,由于环境中普遍存在低频振动,采用了压电悬臂梁结构,建立压电悬臂梁结构的电学模型,并进行了ANSYS的仿真,仿真得到电压76 V,约等于模型的理论值,验证了模型的正确性。进而继续研究了压电悬臂梁几何尺寸对固有频率的影响,振子越长,质量块越长,频率越低。从而收集低频振动环境中的能量,为传感器供电装置提供了设计的理论依据。     

降噪高分子材料及其应用

降噪材料按降噪机理可分为阻尼减振材料、吸声材料和隔声材料。降噪高分子材料可广泛应用于建筑、交通、化工和生活等各个领域。综述了降噪高分子材料的主要种类及其作用机理，并对高分子降噪材料的研究现状和应用情况作了简单的介绍。     

PbNb2O6基压电陶瓷的高温介电性能研究

本文在PbNb2O6基础上采用Ba^2＋取代Pb^2＋离子,并通过添加Cr2O3、Y2O3、Sm2O3、Nd2O3和CeO2等氧化物进行掺杂改性,研究不同掺杂剂对PbNb2O6陶瓷材料结构的影响,寻找提高压电性能及居里温度的途径.试验结果表明,掺杂后的偏铌酸铅显微结构发生了变化,适量的掺杂可获得压电性能和工艺稳定性能很好,且居里温度较高（420℃～600℃）的改性PbNb2O6系压电陶瓷,可分别满足350℃和500℃以上高温应用环境的要求.     

压电陶瓷变压器材料PMMN-PZT的研究

研究了一种四元系压电陶瓷变压器材料PMMN -PZT。XRD分析证明 ,采用二步法预合成的PMMN -PZT粉料不如一步法 ;SEM分析进一步证实了一步法预合成的粉料能制成性能更好的陶瓷样品。造粒工艺对陶瓷样品的显微结构和压电性能也有重要的影响。最后制得了性能较好的PMMN -PZT压电陶瓷材料 ,其Kp=0 .5 18,Qm=3887,tanδ =0 .71% ,εT3 3 /ε0 =70 1,d3 3 =2 0 3,基本上能满足压电变压器的要求     

Mechanical and dynamic mechanical properties of jute fibers–Novolac–epoxy composite laminates

A study was done of jute composite using a polymer matrix of epoxidized Novolac resin (ENR), diglycidyl ether of bisphenol A (DGEBA)–based epoxy, and their blends with different weight percentages of the resins. It was found that on blending ENR with DGEBA, the storage modulii at room temperature are enhanced by about 100% or more in the case of 30 and 40% ENR‐containing matrices, whereas the enhancement in the case of 20 and 12% ENR‐containing matrices is only 50% that of the pure matrix. It was also observed that the tan δ peak heights of the composites containing 30 and 40% ENR are closer to that of 20% ENR‐containing composite. The probable explanation drawn on the basis of experimental findings of DMA and mechanical analysis is that by blending ENR with DGEBA epoxy it is possible to manufacture jute composites with increased stiffness without sacrificing their ductility. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 85: 2800–2807, 2002     

Intrinsic Elastic, Dielectric, and Piezoelectric Losses in Lead Zirconate Titanate Ceramics Determined by an Immittance-Fitting Method

The material coefficients of "soft" and "hard" lead zirconate titanate (PZT) ceramics were determined as complex values by the nonlinear least-squares-fitting of immittance data measured for length-extensional bar resonators. The piezoelectric d -constant should be a complex value to obtain a best fitting between observed and calculated results. Because the elastic, dielectric, and piezoelectric losses determined in this process were not "intrinsic" losses, a calculation process to evaluate the "intrinsic" losses was proposed. It was confirmed that the intrinsic losses were smaller than the corresponding extrinsic losses. The intrinsic piezoelectric loss existed in both soft and hard PZTs; ∼50% of the loss of piezoelectric d -constant was derived from the elastic and dielectric losses. The most notable difference between the soft and hard PZTs was observed in their elastic losses.     

准同型相界附近(Na1-xKx)0.5Bi0.5TiO3的制备及性能研究

利用固相法制备了（Na1-xKx）0.5Bi0.5TiO3系压电陶瓷，XRD分析表明所得陶瓷样品为纯的钙钛矿结构，其准同型相界在x=0．18～0．22之间；电子探针显微分析显示所做陶瓷样品晶粒发育良好，具有规则的外形和明显的晶界；实验所得陶瓷样品损耗tanδ最大不超过5％，最好的压电常数d33=153 pC／N，平面机电耦合系数kp=0．299，它们分别出现在x=0．22和0．20处。     

Damping of vinyl acetate–n‐butyl acrylate copolymers

A photopolymerization process at room temperature was devised to copolymerize vinyl acetate (VAc) and n‐butyl acrylate (BA) mainly to prepare rubber‐like damping sheet bearing pressure‐sensitive adhesive property in this study. The investigations using both the differential scanning calorimeter and rheometric dynamic analysis show the existence of two glass transition temperatures for each copolymer. The scanning electron microscopic pictures reveal that the degree of microphase separation increases with increasing annealing time at 70°C. It was suggested that the rubbery domain (formed by the PBA blocks) disperses in the glassy domain (constituted by the PVAc blocks), making an effective damping entity. Excellent damping was observed for the copolymer samples, with the tanδ peak values as high as 1.76–1.80 at a certain temperature range and with tanδ> 0.3 at quite wide temperature ranges. In addition, the copolymers containing more VAc tend to have the higher damping. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1396–1403, 2004     

基于拥塞预警与分流传输的AOMDV协议优化

针对AOMDV协议只使用主路径传输数据,导致备用路径未能得到充分利用以及网络负载失衡的问题,本文提出一种LBAOMDV(Load Balanced AOMDV)协议。该协议在AOMDV协议的基础上使用基于路径长度、路径使用次数以及路径状态的分流传输机制在多条路径上同时传输数据以均衡网络负载,当网络中的节点负载过重并通过预先设定的阀值时将触发拥塞预警机制以减少通过该节点的数据流量,从而进一步达到网络负载的动态均衡。