本文選題：微懸臂梁　切入點：諧振頻率　出處：《西安交通大學(xué)》2017年博士論文　論文類型：學(xué)位論文

【摘要】：本文針對電力設(shè)備、新能源發(fā)電中電流檢測以及工業(yè)控制、石油勘探、內(nèi)燃機等動力系統(tǒng)中流體密度/黏度在線測量的迫切需求,以微機械懸臂梁諧振傳感器為研究對象,對傳感器的基礎(chǔ)理論、設(shè)計和優(yōu)化、加工、性能測試和應(yīng)用實驗等方面進(jìn)行了系統(tǒng)研究,實現(xiàn)了電流以及流體密度/黏度的在線測量。本文所取得的主要成果有:(1)建立了變截面微懸臂梁的撓度與表面應(yīng)力之間的數(shù)學(xué)關(guān)系式,提出了變截面微懸臂梁一階諧振頻率和綜合靈敏度的計算公式,以優(yōu)化微懸臂梁的結(jié)構(gòu),提高微懸臂梁的綜合靈敏度。(2)建立了一階彎曲模態(tài)下微懸臂梁測量流體密度時的靈敏度數(shù)學(xué)模型,由此推導(dǎo)了矩形微懸臂梁寬度臨界值的數(shù)學(xué)表達(dá)式。通過流固耦合仿真研究,優(yōu)化微懸臂梁的結(jié)構(gòu)形狀和工作模態(tài),以提高密度測量的靈敏度,并提高微懸臂梁的品質(zhì)因子進(jìn)而擴大流體黏度的測量范圍。(3)提出了品質(zhì)因子原則、諧振頻率原則以及傳感器輸出原則等來指導(dǎo)微懸臂梁諧振傳感器的結(jié)構(gòu)設(shè)計,并確定了傳感器采用電磁激勵和壓阻檢測的工作方式。(4)繪制了傳感器芯片的版圖結(jié)構(gòu),制定了傳感器芯片的工藝流程,制作出了微懸臂梁傳感器芯片,實現(xiàn)了傳感器的封裝。(5)搭建了微懸臂梁傳感器實驗系統(tǒng),開發(fā)了數(shù)據(jù)采集與處理軟件。建立了微懸臂梁傳感器的在四種諧振模態(tài)下的等效電路模型。研究了儀器參數(shù)與傳感器工作條件等對微懸臂梁傳感器諧振頻率的影響。提出了改變惠斯通電橋供電電流或者線圈激勵電壓實現(xiàn)傳感器頻率調(diào)諧的機理。(6)基于微懸臂梁傳感器實驗系統(tǒng),對所研制的不同形狀微懸臂梁諧振傳感器在不同的諧振模態(tài)下進(jìn)行了有機試劑的密度/黏度測量實驗研究,實驗結(jié)果表明,在620.83kg/m~3到866.87 kg/m~3的密度測量范圍內(nèi),實驗數(shù)據(jù)與文獻(xiàn)數(shù)據(jù)的最大偏差小于2.00%,在217.9μPa·s到961.8μPa·s的流體黏度范圍內(nèi),最高測量精度小于11.00%,且微懸臂梁諧振傳感器工作于高階模態(tài)有利于提高黏度測量精度。此外,提出了微懸臂梁諧振傳感器實現(xiàn)直流電流測量的工作機理,并通過實驗得到了微懸臂梁諧振傳感器在不同模態(tài)下測量直流電流的精度和靈敏度,在電流為0.5 m A到4.0 m A范圍內(nèi),最高測量精度為0.92%,最大靈敏度為 6.702 Hz/mA~2。
[Abstract]:In order to meet the urgent need of on-line measurement of fluid density / viscosity in power systems such as power equipment, new energy generation, and industrial control, oil exploration, internal combustion engine, this paper takes the micro-mechanical cantilever resonant sensor as the research object. The basic theory, design and optimization, machining, performance test and application experiment of the sensor are systematically studied. The on-line measurement of current and fluid density / viscosity is realized. The main results obtained in this paper are: 1) the mathematical relationship between deflection and surface stress of a variable cross section micro cantilever beam is established. In order to optimize the structure of the micro-cantilever beam, a formula for calculating the first-order resonant frequency and the comprehensive sensitivity of the micro-cantilever beam with variable section is presented in order to optimize the structure of the micro-cantilever beam. The mathematical model of sensitivity of micro-cantilever beam for measuring fluid density in first order bending mode is established, and the mathematical expression of critical value of width of rectangular micro-cantilever beam is derived. In order to improve the sensitivity of density measurement and improve the quality factor of micro cantilever beam, the principle of quality factor is put forward in order to optimize the structure shape and working mode of micro cantilever beam and then expand the measuring range of fluid viscosity. The resonant frequency principle and sensor output principle are used to guide the structure design of micro-cantilever resonant sensor, and it is determined that the sensor uses electromagnetic excitation and piezoresistive detection to work out the layout of the sensor chip. The process flow of the sensor chip is established, the microcantilever sensor chip is made, the sensor package is realized, and the experimental system of the micro cantilever beam sensor is built. The software of data acquisition and processing is developed, and the equivalent circuit model of micro cantilever beam sensor under four resonant modes is established. The influence of instrument parameters and sensor working conditions on the resonant frequency of micro cantilever beam sensor is studied. The mechanism of frequency tuning of the sensor by changing the supply current or coil excitation voltage of the Wheelstone bridge is proposed. The mechanism is based on the microcantilever sensor experimental system. The density / viscosity measurements of organic reagents for different shape microcantilever resonant sensors in different resonant modes have been studied. The experimental results show that the density measurement ranges from 620.83 kg / m ~ (3) to 866.87 kg/m~3. The maximum deviation between the experimental data and the literature data is less than 2.00. In the range of 217.9 渭 Pa 路s to 961.8 渭 Pa 路s, the maximum measurement accuracy is less than 11.00. Moreover, the micro-cantilever resonant sensor can improve the accuracy of viscosity measurement by working in higher-order modes. The working mechanism of DC current measurement by micro-cantilever resonant sensor is presented. The precision and sensitivity of micro-cantilever resonant sensor in different modes are obtained by experiments. In the current range of 0.5 Ma to 4.0 Ma, the highest measurement accuracy is 0.92 and the maximum sensitivity is 6.702 Hz 路mA-2.
【學(xué)位授予單位】：西安交通大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2017
【分類號】：TP212

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