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An algorithm to solve the inverse problem of detecting inclusion interfaces in a piezoelectric structure is proposed. The material interfaces are implicitly represented by level sets which are identified by applying regularization using total variation penalty terms. The inverse problem is solved iteratively and the extended finite element method is used for the analysis of the structure in each iteration. The formulation is presented for three-dimensional structures and inclusions made of different materials are detected by using multiple level sets. The results obtained prove that the iterative procedure proposed can determine the location and approximate shape of material sub-domains in the presence of higher noise levels. 相似文献
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采用传统陶瓷工艺制备了钙钛矿型低铅压电陶瓷xPbTi0.4716Zr0.4834(Mn1/3Sb2/3)0.0450O3-(1-x)(K0.485Na0.485Li0.03)NbO3[xPMS-(1-x)KNLN],研究了该陶瓷体系的结构和介电、压电与铁电性能以及这些结构和性能与工艺条件的关系。XRD分析表明,随着烧结温度的升高,陶瓷晶相由焦绿石相与赝立方钙钛矿相共存转变为单一的四方钙钛矿相;SEM分析表明,在烧结过程中产生了以(K0.485Na0.485Li0.03)NbO3组分为主的液相,并在烧结温度提高的过程中产生孔洞出现-孔洞消失的现象;电学测试表明,xPMS-(1-x)KNLN陶瓷具有良好的性能,在x=0.75、烧结温度为1250℃时,陶瓷的性能参数为压电常数d33=182pC/N,机电耦合系数kp=34.5%,居里温度TC=165℃,剩余极化强度Pr=21.2μC/cm2,矫顽场强Ec=1.47kV/mm,介电常数εr=1879,介电损耗tanδ=0.92%。 相似文献
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随着化石能源的过度使用和开采,随之而来的能源和环境问题也日益尖锐,而人们对能源的需求不减反增,因此寻求一种新型的绿色可持续能源是非常必要的。环境中的能量十分丰富,因此从环境中收集能量进行转化是十分有前景的方法。压电材料在受到外界作用发生机械变形时,能实现机械能向电能的转化,因此,压电式纳米发电机作为一种潜在的可持续、绿色能源,近年来受到广泛关注。从压电材料的分类入手,结合其制备方法、结构和性能等,对近年来一些研究成果进行了概述,详细评价了不同制备方法、结构对压电式纳米发电机压电性能的影响,并对今后发展进行了展望。 相似文献
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采用传统的固相反应合成法制备了0.9(K0.5Na0.5)NbO3-0.1LiSbO3(KNN-LS)无铅压电陶瓷,研究了它在不同直流偏置电场下的介电常数的频谱,并分析了直流偏置电场诱导下的相对介电常数变化值Δrε和调谐率K.随着偏置电场的增大,Δrε和K都变大,这与传统的钛酸锶钡陶瓷类的材料结果相反.同时,随着频率的增加,Δrε和K都减小.Δrε随偏置电压的增加而增大,意味着在高的电压下,样品的色散效应增大,其原因可以用空间电荷的极化理论来解释.另外,在外加偏置电压不高的情况下(3 kV/cm),就可以获得相对较大的调谐率1.17%. 相似文献
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Bin Liu Dai-Ning Fang Ai Kah Soh Keh-Chih Hwang 《International Journal of Fracture》2001,111(4):395-407
In this paper, the influence of dielectric medium inside a crack on crack growth, in an infinite poled or depolarized ceramic, has been studied by employing an electric boundary condition derived from the exact boundary conditions proposed by Sosa (1996). The effect of remanent polarization has also been examined. The results obtained show that electric displacement on crack surfaces is not always zero. Hence, for studying fracture problems of piezoelectric ceramics with cracks accurately, the exact boundary conditions should be implemented. In addition, the results indicate that the effect of remanent polarization is equivalent to that of a positive electric field and it cannot be neglected. It is also found that a positive electric field always has a tendency to open a crack, and a negative electric field tends to close a crack. 相似文献
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超声压电陶瓷换能器可以探测5000m以下深处的地质结构和油井固实程度。用于压电陶瓷换能器的PT-PSN陶瓷性能参数是,Tc=380℃,kt=45%,εr=420,tanδ=1.5%,Qm=2200,Ec=733V/mm。经实验测量和现场试验表明,在温度高达200℃时压电陶瓷换能器的性能稳定,测量精度高。 相似文献
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快速成型和凝胶注模的有机结合是制备复杂结构陶瓷体的有效方法,该工艺的关键是制备高固相、低黏度的注模浆料.采用快速成型和凝胶注模制备复杂结构的PMN-PZT压电陶瓷,重点讨论了分散剂、浆料pH值和球磨时间对注模浆料黏度的影响,并对该工艺和传统模压成型工艺制备的样品进行了形貌分析和电学性能测定.结果表明:当分散剂用量在0.9%~1.1%,pH值为10.5~11.5,球磨时间为8 h时,可以制备出固相含量为55%,黏度小于1 Pa.s的压电陶瓷浆料.使用该浆料制备的复杂结构压电陶瓷体与模压成型工艺相比,显微结构均匀致密、晶粒大小与晶界分布均匀,气孔率更小,电学性能更均匀. 相似文献
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讨论了非线性对正弦相位调制Fabry-Perot(F-P)干涉术的影响.当用分块积分讨论相调F-P干涉术的输出光强,并作近似处理时,就可以给出类似的结果,所以把这种方法进一步推广到对相调F-P干涉术的研究中.同时提出了两种测量压电陶瓷非线性系数的方法,在实际测量得到的非线性系数基础上,完成`影响大小的数值计算和实验研究.最后证明提出,相调F-P干涉术的初相位应选择在π/4附近以及它可用于测量精细表面的粗糙度或其轮廓. 相似文献
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Nenad Bicanic Hua-Peng Chen 《International journal for numerical methods in engineering》1997,40(23):4451-4468
A novel procedure for damage identification of framed structures is proposed, where both the location and the extent of structural damage in framed structures can be correctly determined using only a limited number of measured natural frequencies. No knowledge of the modal shapes of the damaged structure is required. On the basis of the characteristic equations for the original and the damaged structure, a set of equations is generated. Two computational techniques, the direct iteration (DI) technique and the Gauss–Newton least-squares (GNLS) technique, are utilized to determine structural damage from the derived equations. Finally, different numerical examples are used to demonstrate the effectiveness of the proposed method. © 1997 John Wiley & Sons, Ltd. 相似文献
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制备了3种不同类型的无铅压电陶瓷,包括钛酸钡(BT)、钛酸铋钠(BNT)、铌酸钾钠(KNN),用XRD对无铅压电陶瓷进行物相分析;将这3种无铅压电陶瓷与义齿基托树脂聚甲基丙烯酸甲酯(PMMA)粘接,通过粘接剪切强度测试评价了无铅压电陶瓷与义齿基托树脂间的粘接强度.实验结果表明,3种不同的无铅压电陶瓷与义齿基托树脂之间的粘接剪切强度值有统计学的差异(P<0.05),由高到低依次为KNN>BNT>BT;所采用的无铅压电陶瓷与义齿基托树脂之间有良好的粘接性能;粘接破坏形式主要为内聚性破坏.研究结果为无铅压电陶瓷与义齿基托树脂将来在口腔临床治疗中的应用提供了重要的实验依据. 相似文献
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Hashimoto K.-Y. Omori T. Yamaguchi M. 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2009,56(11):2559-2564
This paper describes the characterization of SAW propagation in layered substrate and overlayered structures. The software based on the finite element method and spectral domain analysis was newly developed and applied to the characterization of SAW propagation under an infinitely-long Al interdigital transducer on a rotated Y-cut LiTaO3/sapphire substrate. Because of the finite LiTaO3 thickness, a series of spurious resonances appears. It is shown that the excitation strength of the spurious resonances changes with frequency as well as the rotation angle, which reflects the frequency and rotation angle dependence of the energy leakage. Next, the analysis was carried out for SAWs propagating in a SiO2 layer/Al IDT/42°YX-LiTaO3 structure. It is shown that the influence of the SiO2 layer is significantly dependent on the location where the SiO2 layer is deposited. In particular, it is shown that when the SiO2 layer is deposited only on top of the electrodes, the SAW reflectivity increases compared with when the SiO2 layer is deposited between and on top of electrodes. 相似文献
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以次亚磷酸钠为还原剂,在PMMN系压电陶瓷表面进行碱性化学镀镍作为电极使用;确定了适用于PMMN系压电陶瓷体系的碱性镀液和镀镍工艺参数;通过SEaM对镀镍层表面进行了分析,研究了施镀时间对镀镍层厚度的影响,镀镍时间在15~20min较佳。实验结果表明,PMMN压电陶瓷表面化学镀镍层均匀、致密无开裂现象. 相似文献