高灵敏度宽频带阵列式仿生矢量水听器研究

针对MEMS仿生矢量水听器灵敏度和频带相互制约,不能同时满足宽频带高灵敏度测量的问题,在单个MEMS矢量水听器的基础上,设计了由四个单元构成的2×2单片集成微敏感结构阵列,实现了水听器的高灵敏度和宽频带。通过理论分析和ANSYS仿真分析,确定阵列微结构的尺寸,采用硅微机械加工工艺完成了阵列微结构的加工,最后在水声一级计量站对封装好的水听器进行了灵敏度和指向性校准测试。测试结果表明:该阵列式仿生矢量水听器未加前置放大时灵敏度达到-189 dB,频响范围20～5 000 Hz,具有良好的"8"字型指向性。     

MEMS仿生矢量水听器的微结构优化设计

压阻式的MEMS仿生矢量水听器的固有频率和灵敏度之间是相互制约的,即随微结构的各个尺寸(悬臂梁的长、宽、高及中心连接体的边长)的变化,二者呈现相反的趋势。通过理论分析和推导,得出每个尺寸对水听器固有频率和灵敏度的影响程度不一致,可以合理地设计微结构的各个尺寸(最优解),使矢量水听器在具有相同固有频率条件下得到最大灵敏度。根据常用的微结构,通过Matlab软件计算出了微结构的一组最优解。通过ANSYS软件仿真验证,与常用的微结构相比,该微结构固有频率下降了7%,而灵敏度提高了1倍。最后,测试结果表明:两组尺寸的水听器频带范围为20~1 000 Hz,并且尺寸优化后的水听器比优化前的灵敏度平均高5 dB。     

应用于舷侧阵的分布反馈式光纤激光水听器研究

为减小分布反馈式(DFB)光纤激光器在水声探测时的扰动,设计了一种双膜片式封装结构的光纤激光水听器。该结构通过膜片增大声压作用面积,并转化为激光器的轴向应变以实现增敏。利用有限元软件ANSYS对该结构进行了仿真分析,加工制作了双膜片式结构封装的DFB光纤激光水听器原型样品,并对其进行了水声实验研究。实验测得,研制的双膜片端面增敏结构的DFB光纤激光水听器在2.5~10kHz的平均声压灵敏度为-136.9dB,波动幅度不高于±0.5dB,水听器的工作频带向高频得到了有效拓宽,使其能很好地满足舷侧阵的工程化应用要求。     

一种基于共振腔的新型水听器探究

提出了一种基于共振空气腔的高灵敏、低成本水听器。该水听器为密封的中空球形腔体,内部放置麦克风来感知从水耦合进来的声音。通过有限元仿真预测了水听器的频率响应,并证实频响曲线的特征峰依赖于空气腔共振模态、与球壳共振无关,因此,该水听器的频响特性只取决于内部空气腔尺寸。实验结果表明,该水听器的频率响应与仿真结果符合,与传统压电水听器相比其灵敏度有所提高,在共振频率处的接收灵敏度比传统压电水听器高10倍。     

MEMS矢量水听器定位误差分析与测试

针对一种纤毛式微机械电子(MEMS)矢量水听器的工作原理进行分析,通过分析得出该矢量微传感器的定位误差主要来源于纤毛柱体的偏差.通过有限元仿真分析得出纤毛柱体的偏差对矢量水听器在两个方向上的灵敏度有较大影响,理论计算出在纤毛偏移下2个轴向灵敏度度误差为9.74％.对水听器结构进行轴向灵敏度测试,测出x向灵敏度为0.683 mV/g(其中g为重力加速度),y向灵敏度为0.755 mV/g,两个方向上灵敏度相对误差为9.5％,与仿真结果接近.     

光开关选通的光纤激光水听器时分复用阵列

为了降低传感器系统的成本及体积,利用光纤激光传感单元的特性,采用光开关选通的光纤激光水听器时分复用技术,构建了实用的基于光开关的4元光纤激光水听器时分阵列。进行了理论分析和实验验证,分析了使用光开关选通的光纤激光水听器时分复用阵列方案的选通脉宽和损耗,指出了各通道光脉冲对干涉信号的采样率的限制因素。结果表明,光开关选通的光纤激光水听器时分阵列可以很好地完成复用信号的采集和复用,实验中4元时分复用水听器相邻通道的串扰为-17dB。     

一种压电单晶矢量水听器的性能建模与分析

针对加速度型矢量水听器在低频段灵敏度偏低问题,根据铌锌酸铅-钛酸铅(PZN-PT)压电单晶的性能特点,设计了一种双悬臂梁结构压电单晶矢量水听器。建立了有限元模型,对矢量水听器的振动模态和接收性能进行了仿真计算,重点分析了几个主要材料和尺寸参数对水听器自由场灵敏度的影响。理论计算表明,采用压电单晶PZN-PT的矢量水听器经优化后其灵敏度可达-190 dB@250 Hz,与压电陶瓷PZT-5A的水听器相比,灵敏度提升了15 dB以上。     

DFB光纤激光水听器预应力理论与实验研究

为了研究预应力对分布反馈式(DFB)光纤激光水听器水声探测性能的影响,建立了双膜片结构DFB光纤激光水听器声压灵敏度与预应力关系的理论模型,运用有限元软件ANSYS仿真分析了水听器动态性能与预应力的关系,加工制作了不同预应力作用下的DFB光纤激光水听器原型样品,并在消声水池对其进行了实验研究。实验结果表明,随着预应力的增加,DFB光纤激光水听器的频率响应趋向平坦,当预应力引起的水听器出光波长变化量增大到400 pm时,水听器在2.5~10 k Hz频率范围内的声压灵敏度为136.8 d B±0.3 d B,而预应力继续增大时,水听器的频率响应曲线变化非常小,这与理论分析和仿真结果都吻合较好。     

圆柱状水听器径向振动分析

为了进一步研究圆柱状水听器的径向振动,运用ANSYS软件建模。通过有限元方法,对同种形状不同尺寸的水听器仿真模型进行径向振动求解,得到了圆柱状水听器的径向共振频率与压电陶瓷和金属负载尺寸之间的关系。通过实验证明仿真计算结果的可靠性,从而为下一步圆柱状水听器的设计和研究提供了坚实的基础。     

基于MEMS的压阻式一体化矢量水听器

随着水下探测技术的发展,为满足水听器更精准的定位和更远距离的探测要求,提出了一种基于微电子机械系统(MEMS)的压阻式一体化矢量水听器.设计了一套能够将硅纤毛与二氧化硅悬臂梁相集成的工艺方案,以期解决长期以来由于纤毛二次集成带来的一致性误差.对水听器的性能进行有限元仿真分析,通过应力仿真得出理论上能够将其灵敏度提高约1...     

A new finite element model for reduced order electromagneticmodeling

This paper introduces a new formulation suitable for direct model order reduction of finite element approximations of electromagnetic systems using Krylov subspace methods. The proposed formulation utilizes a finite element model of Maxwell's curl equations to generate a state-space representation of the electromagnetic system most suitable for the implementation of model order reduction techniques based on Krylov subspaces. It is shown that, with a proper selection of the finite element interpolation functions for the fields, the proposed formulation is equivalent to the commonly used approximation of the vector wave equation with tangentially continuous vector finite elements. This equivalence is exploited to improve the computational efficiency of the model order reduction process     

微结构光纤的有限元分析计算法

利用有限元法对零色散点在780nm的均匀微结构光纤进行经过简化的矢量波动方程模拟计算，获得了所需要的模场分布、有效折射率、色散、有效模面积等参数，并与实验数据相参照验证了这种方法的准确性和精度。进而将这种计算方法用于非均匀微结构光纤的模拟计算，不仅获得了很好的结果，与其他方法相比还具有更快的计算速度，计算所得到的结果对将来设计和拉制微结构光纤很有帮助，并且这种方法在设计不规则的微结构光纤方面具有很好的优势。     

压差式光纤矢量水听器声压相位灵敏度研究

该文介绍了压差式光纤矢量水听器及其基元的工作原理,并分析了光纤层等效处理对仿真结果的影响。基于有限元法对压差式光纤矢量水听器的基本性能进行了仿真分析,根据仿真模型所选定的参数研制压差式光纤矢量水听器样品,并对样品在频率为20～1 000 Hz时进行了测试。测试结果表明,声压相位灵敏度的仿真计算结果与实验测试结果基本一致,平均差值约为1.0 dB。研究结果表明,采用有限元法对压差式光纤矢量水听器的声压相位灵敏度进行仿真具有可行性。     

A Hermetic Thick Film Screen-Printed Ceramic Cavity for Harsh Environment Sensing Applications

In this work, a ceramic thick film cavity with screen-printed diaphragm has been designed, fabricated, and fully characterized as the foundation for harsh environment pressure microsensing applications. A new thick film screen-printing technique has been developed as a method for creating the ceramic microstructure. The screen-printed diaphragm was fabricated over a thick film sacrificial layer which was subsequently removed to form the cavity. Hermeticity characterization of the cavity after exposures to elevated temperatures was performed to assess the microstructure's feasibility for harsh environment sensing applications. The ceramic cavity showed excellent hermeticity with a maximum leak rate of 7.0 times 10^-10 atm cc/s He after exposures to temperatures up to 500degC.     

基于低频驱动的微压电能量收集器的结构研究

为给传感器节点持续供电,提出之字形压电悬臂梁,与传统直梁结构相比,其等效加大了悬臂梁的长度,降低了固有频率。对之字形悬臂梁结构建立解析模型,对其振动进行了理论分析,通过仿真软件ANSYS对该结构进行了模态分析。仿真结果表明,在微加工工艺的尺寸限制下,8根直臂梁构成的之字形结构悬臂梁,其一阶固有振动频率小于200Hz,符合与环境振动源形成共振的条件,证明了之字形结构的有效性。     

vf-BGA封装焊球热疲劳可靠性的研究

采用有限元分析方法对 vf- BGA焊球的热疲劳特性进行了模拟 .通过扫描电镜 (SEM)对温度循环试验后焊球金属间化合物 (IMC)层和剪切强度试验后的断裂面进行了形貌、结构和组分的观察及分析 .实验和模拟结果表明 :热疲劳负载下焊球的剪切疲劳强度 ,受到焊球塑性应变能量的积累和分布以及金属间化合物层的厚度和微结构变化导致的界面脆性等因素的影响 .使用 Darveaux能量疲劳模型的裂纹初始化寿命预测结果与实验数据一致     

Cellular handsets antenna modeling by vector finite element method

An algorithm of electromagnetic fields simulation and calculation of cellular handsets antenna parameters by vector finite element method in frequency domain is presented. The algorithm is based on discretization of the electric field equation by Galerkin method using basis functions of various order. Incorporation of lumped elements and ports into finite element model is provided. Fast frequency sweep is used for accelerating solution process in a wide frequency band. Comparison of simulation and experimental results proves high accuracy and reliability of the developed computer code.     

超声微结构加工钻的研究

超声加工是一种新型的特种加工方法,它特别适合于不导电、硬脆和难熔的材料加工。该文利用了精确四端网络法和有限元相结合的方法,设计并制造出可用于微细孔和微三维结构加工的超声钻。通过实验测试的方法,对超声钻进行了测试,验证了有限元分析的结果。同时进行了钻孔实验,对超声钻的性能进行了评估。     

A hybrid FEM/MOM technique for electromagnetic scattering andradiation from dielectric objects with attached wires

A hybrid formulation is presented, which combines the method of moments (MOM) with the edge-based vector finite element method (FEM) to solve electromagnetic radiation problems from structures consisting of an inhomogeneous dielectric body of arbitrary shape attached to one or more perfectly conducting bodies. While either method alone fails to model these structures efficiently, a combination of both finite element and moment methods provides an excellent way to solve these problems. The FEM is employed to handle the interior domain of inhomogeneous dielectric bodies and the method of moments is used to develop surface integrals that relate the field quantities on boundary surfaces with the equivalent surface currents. These integral equations are then coupled to the finite element equations through the continuity of the tangential magnetic fields across the hybrid boundaries     

Edge-based FEM solution of scattering from inhomogeneous andanisotropic objects

This paper presents an application of the edge-based vector finite element method to scattering problems of anisotropic and inhomogeneous objects. Based on conventional FEM functional, a hybrid finite element-surface integral formulation is established by introducing permittivity and permeability tensors. The space domain is divided into interior and exterior regions by an imaginary surface conformal to the scatterer. Edge vector finite elements are used to model the anisotropic and inhomogeneous interior, and a surface integral equation is used to model the unbounded exterior. Compared to other hybrid techniques, the approach here retains the symmetry and sparsity of the FEM matrix and introduces only one type of unknown equivalent current in the moment matrix equation. To validate the theory, typical 2-D numerical results are first presented, which show excellent agreement with exact eigenmode expansion solutions or accurate MoM data