基于圆弧限位的压电发电装置

提出一种基于圆弧限位压电发电装置来提高发电能力及可靠性。介绍了该装置的结构及工作原理,建立了其机电能量转换模型。通过模拟仿真分析获得了压电振子厚度比（基板与总厚度比）对最小限位圆弧半径及能量、及压电振子厚度和限位圆弧半径对电压及能量的影响规律。结果表明,最小限位圆弧半径随厚度比的增加而线性减小,且存在共同的最佳厚度比（0.35）使不同厚度压电振子的输出电压和能量最大;在最佳厚度比时,输出电压和能量随压电振子厚度增加或限位圆弧半径降低而增加。制作了一组限位圆弧半径不等的发电装置,并进行了相关试验测试。结果表明,压电振子的最大输出电压（变形量）仅与限位圆弧半径有关,故采用最小限位圆弧半径可同时获得最大的发电能力和较高的可靠性。     

压电悬臂梁发电装置的建模与仿真分析

为提高一定尺度压电复合悬臂梁（简称压电梁）的发电能力,建立了单、双晶压电梁发电能力的仿真分析模型,研究了结构尺寸、激励方式及材料性能等对其发电能力的影响规律。研究表明,在基板材料及激励条件相同时,存在不同的最佳厚度比使单／双晶压电梁发电能力最大,双晶梁的最大发电量约为单晶梁的2倍。基板材料不同时,最佳厚度比随（基板与压电材料的）杨氏模量比的增加而减小,铝、钼基板构成的单／双晶压电梁的最佳厚度比分别为（0.7,0.32）和（0.45,0.2）。在相同的厚度比（0.5）及外界激励条件下,杨氏模量比对两种电梁发电能力的影响不同,杨氏模量低于3.3时,双晶梁的发电量均大于单晶梁。     

悬臂梁单晶压电发电机的实验

建立了悬臂梁单晶压电振子的发电测试系统,针对压电晶体与磷青铜基板材料的厚度比对单晶压电振子输出电压的影响进行了有限元分析,得出了压电晶体与磷青铜基板材料的最佳厚度比并进行了实验验证,同时对具有最佳厚度比的单晶压电振子进行了压电发电能力测试.研究结果表明,当压电晶体与磷青铜金属基板的最佳厚度比为0.5时,单晶压电振子的输出电压最大,有限元分析与实验结果基本吻合.单晶压电振子输出电压随着负载的增大而增大,而输出功率并不随负载的增大而增大.压电振子存在一个最佳负载,当负载与压电振子内阻相匹配时,输出功率最大,能量转化效率最高.单晶压电振子在负载为50 kΩ时,输出电压最大可达5.4 V;当负载电阻为10 kΩ时,负载与压电振子内阻匹配良好,输出功率达到最大为1.18 mW,产生的能量能满足网络传感器等低耗能电子产品的供能需求.     

压电-气动隔振器的能量回收特性

为实现低频／高强度振动能量回收以及基于能量回收的主动振动控制,提出一种压电-气动隔振器,介绍了其系统构成原理,并进行了其能量回收特性的理论与试验研究。理论分析结果表明,压电-气动隔振器的发电能力是由环境振动强度、气缸／压电振子的结构性能参数、气体容积／背压等多种要素共同决定的。其他条件确定时,发电量／电压随背压增加呈指数规律递增,且存在最佳的压电振子的厚度及厚度比(基板厚度／总厚度)使发电能力最大。采用Φ60×0.9mm3双晶压电振子及Φ16×100mm3气缸制作了试验样机,测试了频率／背压／振动强度对输出电压的影响规律。结果表明,在给定试验条件下,压电 气动隔振器输出电压随背压及气缸活塞振幅的增加线性递增,0.4MPa背压时输出电压约为无背压时的5倍。此外,还存在最佳工作频率(5 Hz)使其输出电压最大。     

双晶悬臂梁压电发电装置发电能力的仿真

针对双晶片悬臂梁式压电振子的理论模型,分析了压电振子的结构参数对压电发电装置发电能力的影响。运用ANSYS有限元软件建立了压电振子的压电耦合模型,研究了压电振子的配重质量、悬臂梁长度和金属基板厚度等结构参数对压电振子的固有频率以及压电发电装置发电量的影响规律。为了验证有限元模型的正确性,对典型结构参数压电悬臂梁的一阶固有频率和发电电压进行了实验测量。仿真结果表明,增加悬臂梁的配置质量和长度、减小悬臂梁基板的厚度都可以降低结构的固有频率,选择恰当的结构参数匹配可以使发电装置的固有频率接近外界的激振频率,从而实现最佳的发电性能。     

悬臂梁单晶压电发电机的实验研究

建立了悬臂梁单晶压电振子的发电测试系统,对压电晶体与磷青铜基板材料的厚度比对单晶压电振子输出电压的影响进行了有限元分析,得出了压电晶体与磷青铜基板材料的最佳厚度比并进行了实验验证,同时对具有最佳厚度比的单晶压电振子进行了压电发电能力测试。研究结果表明,当压电晶体与磷青铜金属基板的最佳厚度比为0.5,单晶压电振子的输出电压最大,有限元分析与实验结果基本吻合。单晶压电振子输出电压随着负载的增大而随之增大,而输出功率并不随负载的增大而增大。压电振子存在一个最佳负载,当负载与压电振子内阻匹配时,此时的输出功率最大,能量转化效率最高。单晶压电振子在负载为50 时,输出电压最大可达5.4 ;当负载电阻为 时,负载与压电振子内阻匹配较好,输出功率达到最大为1.18 ,产生的能量能满足网络传感器等低耗能电子产品的供能需求。     

固支简支压电梁振动及发电特性仿真与试验

为研究固支简支压电梁在简谐位移激励下的发电特性,根据连续系统振动理论建立压电梁的阻尼受迫振动微分方程,按第1类压电方程建立压电梁的机电能量转换数学模型。应用数值分析方法分析压电梁材料、尺寸参数和激励等因素对压电梁发电量的影响和变化规律。对压电梁的输出电压进行了试验研究,试验结果和仿真结果的误差小于8%。研究结果表明,压电梁的电能随梁长度的增加而减小,随梁宽度、压电片和基板厚度的增加而增大,压电片厚度的影响大于基板厚度的影响;压电梁的电能随位移激励幅值的增加以二次曲线形式增加;压电梁输出电压在1阶固有频率附近最大。     

旋磁激励式压电悬臂梁发电机性能分析与试验

为满足旋转机械监测系统的自供电需求,提出一种由旋转磁铁与压电梁端磁铁耦合激励(简称旋磁激励)的新型压电悬臂梁发电机。建立磁力冲击载荷作用下压电梁动态响应模型,通过数值分析方法获得转速、载荷作用时间以及周期比(载荷作用时间与振动周期之比)对压电梁动态响应特性(响应波形及放大比)的影响规律。结果表明,低速时属于脉冲激励,压电梁不发生共振,而高速时属周期激励且存在多个最佳转速使放大比最大。此外,周期比给定时存在最佳转速使放大比最大,转速固定时存在最佳周期比使放大比最大、且最佳周期比随转速增加而增加。在此基础上,测试分析旋转磁铁转速/磁铁厚度以及压电梁端附加质量对发电机发电能力及特性的影响规律,证明旋磁激励式发电机原理的可行性及理论分析结论的合理性;此外,通过确定合理的冲击载荷或采用多个具有不同谐振频率压电梁同步工作的方法可有效提高发电机的速带宽度,实现较大转速范围的实时供电。     

压电电源的关键技术及发展趋势

压电发电机是一种利用周围环境的能量发电,可向微功耗电路供电的能源装置。基于压电陶瓷的压电效应简要地分析了压电发电的工作机理;针对提高压电电源的能量转换量及转换效率,论述了国内外在新型压电材料、压电振子结构、共振频率调节方法及能量收集电路等方面的研究;指出了压电电源向能量来源的多样化、微型化和集成化方向发展。压电电源是绿色可持续能源装置,在航空航天、军工领域以及无线传感网络等方面有广阔的应用前景。     

悬臂梁式压电发电结构理论模型及其仿真研究

为提高压电悬臂梁发电能力以及将压电发电技术应用到日常生活中,开展了压电振动理论分析,建立了压电装置的发电能力与压电材料的厚度比、长度以及悬臂梁的材料、长度等之间的关系,提出了数学建模的分析方法,在理论上对压电悬臂梁的发电能力进行了评价,并进行了Matlab仿真实验.其结果表明:悬臂梁压电发电模型中,压电材料存在最佳厚度...     

Efficiency characteristics of piezostack pump for linear actuators

A piezostack pump for linear actuators is presented and studied in terms of mechanical energy efficiency (MEE), energy conversion efficiency (ECE) and design method. MEE is defined as the ratio of the output mechanical energy to that converted from input electrical energy, and ECE is the ratio of output mechanical energy to input electrical energy. The analysis results show that both MEE and ECE decrease with the increase of stiffness of the chamber diaphragm (k_s), which is a function of the radius ratio (rigid disk radius to chamber radius). There is respective optimal external load (F_c) for them to achieve peak value for a given piezostack with blocked force (F_b) and stiffness (k_a). The optimal force ratio (F_c/F_b) is a constant of 0.5 for maximum MEE, and between 0.57 and 0.5 for maximum ECE. Considering the deflection of the pump chamber and dynamic response of the piezostack, the stiffness ratio (k_s/k_a) should be limited between 0.3 and 1, and the relative radius ratio is between 0.7 and 0.8. With the increase of the radius ratio in the range, the maximal MEE decreases from 0.38 to 0.25, and the peak ECE decreases from 0.20 to 0.14.     

基于能量法的双晶压电悬臂梁发电装置机电耦合系数分析

针对双晶压电悬臂梁发电装置机电两类能量通过压电效应耦合强弱的问题,将能量法应用到双晶压电悬臂梁发电装置机电耦合系数的分析中。开展了双晶压电悬臂梁发电装置机电耦合系数的理论分析,并建立了其与双晶压电悬臂梁发电装置尺寸参数和材料特性之间的关系,对双晶压电悬臂梁发电装置机电耦合系数与其尺寸参数和材料特性的关系模型进行了实验验证和数值模拟。研究结果表明,实验值与理论解有较好的一致性,且都在压电片厚度为0.25 mm时开路电压最大,验证了该理论模型的可靠性。此外,随着压电梁厚度比的不断增大,其机电耦合系数单调递增;同时,较大的弹性模量比有利于压电梁机电耦合系数的提高,且相对于钢弹性基片,铍青铜弹性基片更有利于压电梁机电耦合系数的提高。     

Performance analysis of piezoelectric bimorph generator

In this paper, the theoretical model and simulation of the performance of a piezoelectric (PZT) bimorph generator is introduced. The generator consists of two piezoelectric plates bonded on a substrate metal plate. For an effective electromechanical coupling coefficient (EECC) and the generated energy, the analytical formulae are established with the thickness ratio and the Young’s modulus ratio as variables. After giving correlative material parameters, the EECC and generated energy can be computed. The results show that there is a optimal thickness ratio for a piezoelectric bimorph generator to achieve the maximum EECC and electrical energy. The EECC and generated energy decrease with an increase of the Young’s modulus ratio. In addition, the influence of mechanical source on electrical energy generation and power output is also considered.     

Performance analysis of piezoelectric bimorph generator

In this paper, the theoretical model and simulation of the performance of a piezoelectric (PZT) bimorph generator is introduced. The generator consists of two piezoelectric plates bonded on a substrate metal plate. For an effective electromechanical coupling coefficient (EECC) and the generated energy, the analytical formulae are established with the thickness ratio and the Young’s modulus ratio as variables. After giving correlative material parameters, the EECC and generated energy can be computed. The results show that there is a optimal thickness ratio for a piezoelectric bimorph generator to achieve the maximum EECC and electrical energy. The EECC and generated energy decrease with an increase of the Young’s modulus ratio. In addition, the influence of mechanical source on electrical energy generation and power output is also considered.     

Optimization of composite flywheel design

Composite flywheels are effective energy storage devices. The multi-rimmed flywheel configuration is first chosen for this study because of its superior operating characteristics and versatility. Then the Kevlar-49/epoxy system is adopted as the basic composite material, which is sandwiched between thin layers of rubber. A general stress analysis procedure is developed for the multi-rimmed structure and a computer routine is established to investigate the effects of various material and geometric parameters on the internal stress levels. A maximum stress criterion is used for failure of the composite flywheel. The basic goal of optimization is to achieve a stress distribution such that each ring in the multi-ringed structure will fail at approximately the same angular speed. The parameters varied in the optimization process include the thickness, Poisson's ratio, Young's modulus and density of the inter-ring material, the density and thickness of the composite material, and the thickness of the flywheel in the axial direction. The optimization process demonstrated that this procedure can be applied in general when other failure criteria or performance characteristics (such as maximum kinetic energy, kinetic energy per weight and kinetic energy per volume) are preferred.     

Efficiency characteristics of piezostack pump for linear actuators

A piezostack pump for linear actuators is presented and studied in terms of mechanical energy efficiency (MEE), energy conversion efficiency (ECE) and design method. MEE is defined as the ratio of the output mechanical energy to that converted from input electrical energy, and ECE is the ratio of output mechanical energy to input electrical energy. The analysis results show that both MEE and ECE decrease with the increase of stiffness of the chamber diaphragm (k _s), which is a function of the radius ratio (rigid disk radius to chamber radius). There is respective optimal external load (F _c) for them to achieve peak value for a given piezostack with blocked force (F _b) and stiffness (k _a). The optimal force ratio (F _c/F _b) is a constant of 0.5 for maximum MEE, and between 0.57 and 0.5 for maximum ECE. Considering the deflection of the pump chamber and dynamic response of the piezostack, the stiffness ratio (k _s/k _a) should be limited between 0.3 and 1, and the relative radius ratio is between 0.7 and 0.8. With the increase of the radius ratio in the range, the maximal MEE decreases from 0.38 to 0.25, and the peak ECE decreases from 0.20 to 0.14.     

Thermal buckling of functionally graded rectangular plates subjected to partial heating

We present the thermal buckling analysis of functionally graded rectangular plates subjected to partial heating in a plane and uniform temperature rise through its thickness. The plate is simply supported for out-of-plane deformation and perfectly clamped for in-plane deformation. It is assumed that the functionally graded material properties such as the coefficient of linear thermal expansion and Young's modulus are changed individually in the thickness direction of the plate with the power law, while Poisson's ratio is assumed to be constant. Analytical developments consist of two stages. First, the nonuniform in-plane resultant forces are determined by solving a plane thermoelastic problem. Then the critical buckling temperatures of the plates with the predetermined resultant forces are calculated as the generalized eigenvalue problem which is constructed by using the Galerkin method. Finally, the effects of material inhomogeneity, aspect ratio, and heated region on the critical buckling temperatures are examined.     

光学非球面加工中研抛盘尺寸合理选择的研究

在光学非球面研抛加工中,研抛盘尺寸的合理选择是面形误差有效收敛的关键参数之一。在其他工艺条件保持不变的情况下,推导出了研抛盘的径厚比、弹性模量与工件表面的法向非球面度、法向矢高之间的解析关系;并根据加工过程中的进给步距和不同波长面形误差的特征分析了研抛盘直径的合理取值范围。     

Note: Mechanical study of micromachined polydimethylsiloxane elastic microposts

This paper reports the detailed statistical measurement of Young's modulus (E) and spring constant of micromachined three-dimensional polydimethylsiloxane microposts with various sizes using atomic force microscope. The paper also describes the design and fabrication of these microposts. The micropost array was fabricated with a height to diameter aspect ratio of up to 10. We have found that posts with different sizes have different E values, and posts that are cured at room temperature have smaller Young's modulus than the ones that are cured at 65?°C for the same duration.