悬臂梁易损部件在矩形加速度脉冲激励下的动力学响应与有限元分析

为分析悬臂梁易损部件在矩形脉冲激励下的振动响应,推导出悬臂梁在悬臂端处动态应力的近似解析解,得到最大应力与矩形脉冲峰值之间的关系,分析结果表明：在速度变化量一定时,最大应力随加速度脉冲幅值的增加而增加,但会无限逼近极限值。最后建立了易损件-质量主体在矩形脉冲激励下的有限元模型,并与解析解进行了对比,发现运用2阶振动模态即可得到精确的悬臂梁的应力响应,所取得的研究成果为具有悬臂梁式易损件在蜂窝纸板缓冲作用下的防护提供理论基础。     

Vibration Characteristics of Fatigue Damage of Beam-Type Structural Components

We consider free vibration of an elastic cantilever beam with a closing edge crack. The crack is simulated by an elastic pivot whose compliance is taken to be finite and is determined from the energy equivalence criterion. An algorithm has been constructed for sequential calculation of the beam vibration modes for each beam vibration cycle, whereas the number of cycles is limited. It is demonstrated that the beam vibration modes other than the initially preset one are induced during the crack opening and closing. The distinct features of such modes have been studied. We have analyzed the sensitivity of the vibration-damage characteristics which are determined from the assessment of nonlinear distortions of the displacement, acceleration, and strain waveform of the cross sections of the beam with a closing crack.     

主梁式TBM关键结构参数对其动力学特性的影响规律

全断面岩石隧道掘进机(TBM)在掘进过程中,承受不断变化的大推力、大扭矩、倾覆力矩等随机载荷,引起主机较大的振动。为了减少主机系统各部件的疲劳失效,提高掘进效率,基于动力学仿真软件建立了主梁式TBM主机系统动力学模型,研究主机系统的动力学特性及主梁结构参数对其动力学特性的影响规律。研究结果表明:主梁1长度增加会导致主梁1振动变大,主梁2和鞍架的振动减小。主梁1板厚增加会导致主梁1振动减小,主梁2的振动缓慢增大,鞍架的振动先增加后减小,在上、下腹板厚度50 mm,侧板厚度40 mm,前、后法兰厚度105 mm时,振动达到最大值;刀盘掘进方向的加速度有效值为1.1 g,主梁加速度有效值为0.21 g,随着向后传递振动逐渐减弱,振动频率主要集中在0~50 Hz;依据仿真结果确定了主梁的相关参数,该TBM在某引水工程中经过2年的应用,工程已顺利贯通;现场测试结果表明,三向振动测试数据与仿真结果的误差基本低于20%。     

Modeling Piezoresistive Microcantilever Sensor Response to Surface Stress for Biochemical Sensors

This paper considers mechanical stress and strain in a piezoresistive cantilever sensor under surface stress loading, which is the loading condition that occurs in biochemical sensing applications. Finite element simulations examine the piezoresistor sensitivity due to changes in cantilever length, width, and thickness, and piezoresistor size, location, and depth. A few unexpected results are found. Unlike cantilevers designed for atomic force microscopy, cantilevers for biochemical sensing should be short and wide. While shallow piezoresistors offer good sensitivity, the piezoresistor may extend far into the thickness of the cantilever and still be quite effective. The paper concludes with comments on design guidelines for piezoresistive cantilever sensors.     

On determination of vibration characteristics of a beam with a closing crack in bending vibrations

We consider free vibrations of an elastic cantilever beam with an edge crack, which is simulated as a beam portion with a decreased moment of inertia. The weight of this portion is assumed to be constant, while the dimensions of the portion are determined by the energy criterion of equivalence. We propose an analytical approach to determination of natural frequencies and vibration modes, of a beam with an open or closing crack and to investigation of nonlinear distortions of the displacement wave and acceleration and deformation of various sections of a beam with a closing crack. The solution allows for the possibility that more than one vibration mode of a beam can be generated at the moment of the crack opening and includes the effect of the crack on the strain distribution in the beam volume. It is demonstrated that the approach we propose gives reliable relationships between various vibration characteristics of a beam and the crack parameters and makes it possible to solve an inverse problem of damage diagnostics. Institute of Problems of Strength, National Academy of Sciences of Ukraine, Kiev, Ukraine. Translated from Problemy Prochnosti, No. 3, pp. 5–23, May–June, 2000.     

高量程MEMS加速度计灌封后的动态响应

对双悬臂梁高量程MEMS加速度传感器的封装结构进行了1×105g峰值的半正弦加速度冲击载荷下的有限元响应分析。灌封胶弹性模量的变化对加速度计的输出信号(输出电压、悬臂梁的挠度)的影响可以忽略。输出电压曲线的峰值与解析解接近。加速度计的悬臂梁表现为有阻尼下的受迫振动,并表现出悬臂梁的固有频率特性。输出信号的峰值与加速度载荷的峰值均呈很好的线性关系。灌封胶的弹性模量大于4GPa时胶已经足够硬,适宜用于保护芯片。     

Symmetrical PolyMUMPs-Based Piezoresistive Microcantilever Sensors With On-Chip Temperature Compensation for Microfluidics Applications

Microelectromechanical systems (MEMS)-based cantilever beam sensors for microfluidics applications with on-chip temperature sensors for temperature drift compensation were developed. The stress induced on gold surface with polysilicon piezoresistive sensing is demonstrated. In principle, adsorption of biochemical species on a functionalized surface of the microfabricated cantilever will cause surface stress and, consequently, cantilever bending. The sensing mechanism relies on the piezoresistive properties of the doped polysilicon wire encapsulated in the beam. The beam is constructed through multiusers MEMS Process (PolyMUMPs) foundry with postprocessing silicon etching. Bending analysis is performed so that the beam tip deflection can be predicted. The piezoresistor designs on the beams were varied, within certain constraints, so that the sensitivity of the sensing technique could be measured by external read-out circuit. The mass detection of 0.0058-0.0110 g is measured by the beam resistor series as a balanced Wheatstone bridge configuration. The voltage output of the bridge is directly proportional to the amount of bending in the MEMS cantilever. The temperature dependency and sensor performance have been characterized in experiments. Compensation by resisters on the substrate significantly reduces the temperature dependence.     

单斜面索拱支承曲梁人行桥人致振动控制研究

进行了一种单斜面索拱支承曲梁人行桥的人致振动控制研究。在人行桥的初始状态及静动力特性基础上,模拟了随机人群荷载作用下人行桥的振动响应,参数化地研究了调谐质量阻尼器(Tuned Mass Damper,TMD)的减振作用,考虑了TMD不同质量比、刚度、阻尼参数以及布置方式的影响。在TMD装置安装前后对人行桥进行实地动力测试,测试了结构减振前后的模态特性以及在单人、多人和人群荷载工况下的振动响应,讨论了TMD装置对该类型人行桥的减振效果。结果表明:减振后结构关键模态阻尼增大为减振前的4.14倍;单人步行和跑动工况下,通过设置TMD,结构加速度峰值下降31.1%～55.9%,加速度均方根下降36.4%～52.0%;多种人群步行工况下,结构竖向加速度峰值最大为0.41 m/s~2。研究结果表明单斜面索拱支承曲梁人行桥刚度较柔,TMD对控制该类型人行桥结构人致振动具有很好的效果。     

中低频集中质量悬臂式簧片仪基频分析方法研究

簧片仪是一种中低频冲击响应谱测量装置,设计时可将其简化为端部附带集中质量的悬臂梁。簧片仪的振型方程中存在超越函数,对于等截面簧片仪来说,可使用二分法等数值方法求解,计算量较大,该方法不适用于复杂截面簧片仪基频设计。首先利用悬臂梁自由端受集中力的挠度公式,推导出其等效刚度等效单自由度的弹簧振子系统,利用弹簧振子相关频率公式解决求解集中质量等截面悬臂梁的基频问题,该方法与振型方程求解的基频对比,发现在10 Hz以下的中低频区域,可以很好的保证等截面悬臂梁的基频精度,大于10 Hz的中频段,误差随频率的升高而迅速增大。接下来,通过Mohr积分的方法,推导出等强度集中质量悬臂梁自由端的最大挠度,并给出其基频的设计公式,该方法与试验进行对比,发现误差与等截面悬臂梁有相同趋势,因此利用瑞利能量法修正设计公式中的质量参数,修正后与实验误差在5%左右。经理论与试验验证,所提出的簧片仪设计方法简单可行、计算结果可信。     

大孔径反射镜组件随机振动响应分析与试验

大孔径反射镜的柔性支撑在随机振动试验中应力响应较大,可能产生残余应变进而导致空间光学遥感器成像质量下降,因此,对大孔径反射镜组件进行随机振动响应分析尤为必要。阐述了随机振动分析的基本原理及其有限元实现。建立了反射镜组件的有限元模型,对其进行了随机振动响应分析,得出了反射镜的加速度均方根响应和柔性支撑的均值应力响应。分析结果表明：反射镜加速度响应均方根为16.3Grms;柔性支撑的均值应力响应为34.9MPa。随后进行了随机振动试验验证,结果表明：反射镜组件均方根加速度响应为16.0Grms;均值应力响应为30.3MPa。均方根加速度响应分析误差为1.8%,均值应力分析误差为13.2%,满足精度要求,验证了该方法的正确性。     

一种基于压电堆执行器的柔性结构滞后补偿PID控制

采用压电叠堆执行器和PID控制相结合方法解决柔性结构振动问题。提出相位补偿和分频控制相结合的方法分别解决柔性结构中存在的相位滞后和多频激励问题。首先通过有限元分析方法对柔性梁结构进行理论模态分析,并搭建实验系统进行验证,确定系统的主导模态。然后对系统延时进行理论分析,通过实验辨识出激励频率与滞后补偿的函数关系。最后设计基于滞后补偿的分频PID控制器,通过实验验证多频振动激励条件下所设计控制器的振动控制效果。结果表明所设计的滞后补偿PID控制器对相位滞后有较好补偿效果,最大振动衰减可达45%。     

Energy dissipation in microfluidic beam resonators: Dependence on mode number

Energy dissipation experienced by vibrating microcantilever beams immersed in fluid is strongly dependent on the mode of vibration, with quality factors typically increasing with mode number. Recently, we examined energy dissipation in a new class of cantilever device that embeds a microfluidic channel in its interior-the fundamental mode of vibration only was considered. Due to its importance in practice, we examine the effect of mode number on energy dissipation in these microfluidic beam resonators. Interestingly, and in contrast to other cantilever devices, we find that the quality factor typically decreases with increasing mode number. We explore the underlying physical mechanisms leading to this counterintuitive behavior, and provide a detailed comparison to experimental measurements for which good agreement is found.     

一种基于均方比值的人致结构振动加速度响应信号筛选方法

提出了一种基于人致楼板振动响应的加速度均方根值参数,该参数是结构振动响应信号均方根值和加权均方根值的比值,该参数能够快速判断采集到的人致楼板构振动信号数据是否异常。通过人致楼板振动响应均方根值的理论推导得到了该参数的具体表达式,同时通过建立施加不同工况的人群荷载有限元楼板模型,和不同工况人群作用下楼板振动现场试验,对该参数的性质进行了论证,该参数受人群荷载的参数影响小,与结构自身的基本性质相关性大,在处理大量数据信号时,可以通过该参数对数据进行快速筛选。     

两侧受液时悬臂梁的自由振动分析

本文研究悬臂梁在两侧受有液体作用时的横向自由振动问题,给出了两侧液深不等时悬臂梁自由振动的振型函数和固有频率的精确计算公式,结果可由计算机解出。分析表明,液体对悬臂梁自由振动的影响等效一附着于梁上的广义分布质量。     

可调永磁双稳态非线性能量阱及应用研究

为了实现对主系统的宽频振动抑制,研发了一种可调的双稳态非线性能量阱(BNES)。介绍了BNES的结构和工作原理;其次分析了BNES的刚度构成以及其非线性动力学特性,并建立了悬臂梁-BNES系统动力学微分方程;采用数值方法探究了不同磁铁间距时的BNES对悬臂梁瞬态时域振动抑制效果和稳态频域的宽频抑振能力;对两组不同的悬臂梁系统进行了实验,验证了不同磁铁间距时的双稳态非线性能量阱的宽频振动抑制能力。研究结果表明,该BNES对悬臂梁的瞬态时域响应和稳态频域响应都有很好的振动抑制能力。     

Timoshenko梁的行波与模态的混合控制方法

基于Timoshenko梁理论，采用行波控制和独立模态空间混合方法。对悬臂梁的振动主动控制问题进行了研究。采用行波方法实现了对Timoshenko梁结构的振动控制。首先。采用模态控制方法，控制低频振动。而后，采用行波控制方法吸收高频振动能量，实现结构的振动控制。可见，行波／模态混合控制提高了振动控制精度和系统的鲁棒性。本文给出了悬臂梁振动的混合控制策略，最后给出了数值仿真结果。     

Investigation on vibration scuffing life curves

The printing images on products and packaging play an important role in increasing the business value, adding artistic quality, and sending information. During transportation, scuffing of the printing images will emerge due to vibrations and impacts induced by rough roads and vehicles. This paper investigates experimentally the vibration scuffing through an ink transfer device. The scuffing value–time curves are obtained. Then the scuffing life curves G_rms,e‐N_a,e based on excitation acceleration root‐mean‐square (RMS) and G_rms,r‐N_a,r based on relative acceleration RMS are developed. Both Basquin‐type and exponential‐type curves may be applied to describe the scuffing life in this case. The excitation frequency width covering the resonance frequency has a significant effect on the scuffing life curve G_rms,e‐N_a,e based on excitation acceleration RMS; however, it is not obvious on the scuffing life curve G_rms,r‐N_a,r based on relative acceleration RMS. The vibration system filters out the broadband excitation vibration frequencies away from the resonance zone and makes the relative acceleration signal a narrow one. The scuffing life curve in the resonance scuffing state is very different from that in the nonresonance scuffing state, and they should be distinguished in practical application. The scuffing life equations and curves obtained in this paper may provide a reference to the further research on packaging scuffing and its test evaluation and accelerated vibration test in laboratory.     

收集环境振动能微压电悬臂梁的制作工艺与测试

研制长寿稳定电源已经成为微型无线传感网络中亟待解决的关键技术问题,现有的化学电池容量有限,需要不断地逐个更换耗尽的电池,难以满足无线传感网络的实际应用.提出了利用压电材料的机电耦合特性收集环境振动能,设计了一种用来收集环境振动能的压电微悬臂梁结构,介绍了用MEMS工艺制作带质量块的硅基压电悬臂梁微电源的工艺流程.质量块可以降低器件的谐振频率,并提高输出电功率.最后,对制作的微压电悬臂梁进行了固有频率测试以及静态和准静态标定实验.     

Electrostatically actuated resonant microcantilever beam in CMOS technology for the detection of chemical weapons

The design, fabrication, and testing of a resonant cantilever beam in complementary metal-oxide semiconductor (CMOS) technology is presented in this paper. The resonant cantilever beam is a gas-sensing device capable of monitoring hazardous vapors and gases at trace concentrations. The new design of the cantilever beam described here includes interdigitated fingers for electrostatic actuation and a piezoresistive Wheatstone bridge design to read out the deflection signal. The reference resistors of the Wheatstone bridge are fabricated on auxiliary beams that are immediately adjacent to the actuated device. The whole device is fabricated using a 0.6-/spl mu/m, three-metal, double-poly CMOS process, combined with subsequent micromachining steps. A custom polymer layer is applied to the surface of the microcantilever beam to enhance its sorptivity to a chemical nerve agent. Exposing the sensor with the nerve agent simulant dimethylmethylphosphonate (DMMP), provided a demonstrated detection at a concentration of 20 ppb or 0.1 mg/m/sup 3/. These initial promising results were attained with a relatively simple design, fabricated in standard CMOS, which could offer an inexpensive option for mass production of a miniature chemical detector, which contains on chip electronics integrated to the cantilever beam.     

侧壁压阻式力传感器的研制与标定

在对现有微操作中夹持力问题进行分析的基础上,提出了一种基于面内侧壁压阻的力传感器加工方法,成功地在MEMS微夹持器上集成了压阻式的力检测传感器,对夹持力的检测反馈实现了微操作的闭环控制.该方法利用离子注入工艺和深度反应离子刻蚀（DRIE）工艺相结合制作检测梁侧壁压阻,改善了侧壁压阻工艺与其他工艺间的兼容性问题.最后通过压电叠堆驱动平台结合精密电子秤对压阻传感器进行了标定.测试表明,这种微力传感器加工技术可以很好地与其他工艺相兼容,力传感器的灵敏度优于72V/N,分辨率优于3μN.