新型微加速度计研究进展

微加速度计是一类极为重要的微惯性传感器,广泛应用于振动检测、惯性测量、惯性导航等多个技术行业。随着微纳加工技术的日趋成熟,微加速度计技术的发展受到广泛关注。中文对近年来基于微机电系统和微光机电系统的微加速度计最新研究进展进行综述,简要介绍各种微加速度计的基本工作原理、优势和不足之处,并对各种类型微加速度计的性能进行综合对比分析,讨论出适用于高精度惯性测量及惯性导航等应用方向的微加速度计设计方案,最后分析其仍面临的各种技术挑战,展望未来发展方向。     

粘胶材料参数对微加速度计零位温度漂移的影响研究

粘胶材料常用于实现微加速度计芯片与基底的粘接。为了研究粘胶材料参数对微加速度计零位温度稳定性的影响,首先根据微加速度计理论输出模型,分析了影响零位温度漂移的关键变形。其次,基于典型的芯片-粘胶-基底热变形解析模型,研究了粘胶的弹性模量、热膨胀系数和厚度对该变形的影响,并且理论计算了在常用材料参数范围内,微加速度计的零位温度漂移量。研究表明,弹性模量对零位温漂影响最大,采用软胶(弹性模量小)粘贴能够有效地提高微加速度计的温度稳定性。最后,利用2种粘胶分别粘贴微加速度计,通过比较这2类微加速度计的温漂测试结果,实验验证了结论的正确性。     

考虑边缘和寄生电容的微加速度计的非线性误差研究

为了使微加速度计满足线性度指标,准确计算微加速度计的非线性误差是非常必要的。在考虑边缘和寄生电容的前提下,提出了计算微加速度计的非线性误差的方法。首先根据表芯结构的电容分布特点建立了其等效电路模型,并推导了微加速度计的输出电压与检测电容和寄生电容之间的关系式,其中检测电容包含了边缘电容;其次,基于有限元法,分别提出了计算微加速度计的寄生电容和检测电容的方法;最后建立了微加速度计的输出电压与输入加速度之间的关系式,并基于三次多项式拟合,推导出微加速度计的非线性误差的计算公式。通过对比分析非线性误差的理论计算结果与实验测量结果,提出的方法的正确性得到了验证。     

硅三明治型微机械加速度计温度漂移与敏感结构热膨胀关系研究

针对硅基三明治型微加速度计的温度漂移现象,基于力学和热学原理,分析了微加速度计敏感部分关键结构弹性梁、敏感质量块在温度升高时的热膨胀与力学平衡关系变化。结合微加速度计的闭环反馈工作方式,导出了其输出改变,指出由于弹性梁、敏感质量块在温度升高时热膨胀引起的输出变化小于0.002gn/10℃,同时,实验表明微加速度计输出随温度的变化为(0.1~0.2)gn/10℃。两者对比的结果显示,由于温度变化而引起的敏感结构热膨胀导致的输出改变不是微加速度计产生温度漂移的主导原因,研究结果为三明治型微加速度计稳定性与漂移的进一步研究提供了参考。     

基于Σ-Δ调制技术的微加速度计系统研究

论述了Σ-Δ调制器的基本原理,将Σ-Δ调制技术应用于微加速度计系统,设计了一种新型的微加速度计,建立了系统模型。并对系统的频率特性进行了分析,表明基于该技术的微加速度计系统在工作频段内噪声能够得到有效的消除,且具有近似的线性相位。     

基于∑-△调制技术的微加速度计系统研究

论述了∑-△调制器的基本原理,将∑-△调制技术应用于微加速度计系统,设计了一种新型的微加速度计,建立了系统模型.并对系统的频率特性进行了分析,表明基于该技术的微加速度计系统在工作频段内噪声能够得到有效的消除,且具有近似的线性相位.     

硅微谐振式加速度计的实现及性能测试

为了提高硅微谐振式加速度计性能,从一种基于DDSOG(Deep Dry Silicon on Glass)工艺的硅微谐振式加速度计样机入手,介绍了加速度计的结构、加工方法和接口电路。该谐振式加速度计结构包括敏感质量块、谐振器和微杠杆3部分,采用差动结构来减小共模误差的影响。接口电路中采用了自动增益控制电路来稳定谐振器的振幅,成功实现了谐振器的闭环自激振荡和频率检测。分析了谐振式加速度计频率输出与加速度输入的关系,测试了硅微谐振式加速度计样机性能,结果为量程±50g,标度因数143 Hz/g,零偏稳定性1.2 mg,零偏重复性0.88 mg,阈值170μg。文章最后提出,DDSOG工艺中采用的玻璃材料和硅材料温度系数不同,影响了加速度计的温度特性,因此需要进步一改进加工工艺。     

挠性摆式微硅加速度计的有限元分析

】微硅加速度计是近年来发展起来的新型器件,在结构设计阶段必须对其进行力学分析,以期对使用条件下的摆片位移、应力等作到心中有数。本文采用有限元分析方法对挠性摆式微硅加速度计进行有限元分析,其中包括对未封装及封装后实体单元进行敏感轴位移、侧向位移、横向灵敏度、受力情况等分析。分析结果表明所设计的微硅加速度计符合仪表性能要求。     

批量微加速度计翻滚实验平台设计

针对目前微加速度计重力场翻滚实验设备一次只能对一只加速度计进行测试,基于SolidWorks软件平台设计了一种可一次对多只微加速度计进行翻滚实验,并且微加速度计夹具能与翻滚驱动装置自动结合与分离的新型翻滚实验平台。通过对用该平台测试的加速度计参数和现有设备测试的加速度计参数的对比表明,该平台一次可准确的对4只加速度计进行测试。     

基亏∑-△调制技术的微加速度计系统研究

论述了∑-△调制器的基本原理，将∑-△调制技术应用于微加速度计系统，设计了一种新型的微加速度计，建立了系统模型。并对系统的频率特性进行了分析，表明基于该技术的微加速度计系统在工作频段内噪声能够得到有效的消除，且具有近似的线性相位。     

CURING PROCESS OF PHOTOPOLYMER RESIN BOND DIAMOND TOOLS

Analytical simulation and corresponding proof-test are adopted to study the principle of the curing process of photopolymer resin diamond tools. The influence of the diamond as abrasives in photopolymer resin owing to the absorptivity of the diamond for the UV light on the photopolymer resin curing process is discussed. Based on the above, a kind of diamond tool—dicing blade is selected to analyze the curing process of photopolymer bond diamond tools. An analytical model of curing process is developed and a correlation curve between the depth of polymerization of the photopolymer resin diamond tools and the exposure time to represent the curing process of photopolymer bond dicing blade. A test is done to proof-test the validity of the analytical model and the correlation curve. The simulated data fit the experimental results, which demonstrates the analytical models and numerical algorithm are of high reliability. The analytical simulation method could possibly be used to optimize the curing cycle and improve the quality of the photopolymers resin bond diamond tools.     

Effects of prebuckling deformations on the elastic flexural-torsional buckling of laterally fixed arches

The effect of the prebuckling in-plane deformations on the elastic flexural-torsional buckling of laterally fixed circular arches is studied in this paper. The finite strains and the energy equation for the flexural-torsional buckling of arches have been derived based on an accurate orthogonal rotation matrix. A closed form solution for the elastic flexural-torsional buckling resistance of laterally fixed arches in uniform bending, including the effects of the prebuckling deformations, is obtained. It is found that the notion that the prebuckling deformations increase the flexural-torsional buckling moment of an arch or of a beam is not necessarily correct for a laterally fixed arch or beam in uniform bending, in deference to a laterally pinned arch. When a laterally fixed arch is subjected to positive uniform bending, the effects of the prebuckling deformations decrease the buckling moment, and the reduction of the buckling moment increases with an increase of the included angle and of the out-of-plane slenderness ratio of the arch. When a laterally fixed arch is subjected to negative uniform bending, the effects of the prebuckling deformations decrease the absolute value of its buckling moment when the included angle is very small, but increase the absolute value of the buckling moment when the included angle exceeds a certain value. The increase in the absolute value of the buckling moment increases with an increase of the included angle and of the out-of-plane slenderness ratio of the arch. When the ratio of the out-of-plane to the in-plane second moments of area of the cross-section is not small, both the reduction of the buckling moment of a laterally fixed arch in positive uniform bending and the increase of the buckling moment of a laterally fixed arch in negative uniform bending, are substantial.     

Research on key techniques of expendable conductivity temperature depth measuring system

This paper analysis the developing of expendable conductivity temperature depth measuring system(XCTD)and introduce its principle of measuring about temperature,salinity and depth of ocean.Some key techniques are put forward.According to the real needs of XCTD,conductivity sensor with high sensitivity is designed by principle of electromagnetic induce,the ocean conductivity from induced electromotive force has been calculated.Adding temperature correction circuit would help to reduce error of conductivity measurement because of sharply changing temperature.Advanced temperature measuring circuit of high precision and the constant current source is used to weaken effect of self-heating of resistance and fluctuation of the source.On respect of remote data transmission,LVDS is a good choice for the purpose of guarantee the quality of data transmitted and the transmission distance is reaching to thousand meters in the seawater.Modular programming method is also brought into this research aimed at improve the stability,reliability and maintainability of the whole measuring system.In February,2015,the trials in South China Sea demonstrate that the developed XCTD realize effective measurement at a speed of 6 knots and detection depth at 800 m.The consistency coefficient of the acquired data is greater than 0.99 and the success rate of probe launching is above 90%.     

INFLUENCE OF ROLL DIAMETERS ON DEFORMATION BEHAVIOUR OF HIGH TEMPERATURE SUPERCONDUCTING TAPE

During plastic process,the material flow is strongly influenced by the contact area between deformed workpiece and die.In rolling process,difference of roll diameter makes the contact area between roll and deformed tape different,which leads to different material flow and the distribution of powder density.A numerical modelling of the first rolling process for 61-filament high temperature superconducting tape is constructed and the influences of roll diameters on deformation behavior of the tape are discussed.It can be found that the BiSrCaCuO(BSCCO)powder in the center of the tape has higher relative density than those in the periphery of the tape during rolling process.With the increase of roll diameter,the length of the contact arc in the roll gap expands which lead to the in- creasing of transversal strain and the decreasing of the related longitudinal strain.It makes the value of longitudinal strain ratio decrease gradually,which decreases the possibility of occurrence of the transversal shear band,simultaneously it increases the risk of occurrence of longitudinal crack.     

CHARACTERISTCS OF FLUID FILM IN OPTIMIZED SPIRAL GROOVE MECHANICAL SEAL

In order to investigate the sealing performance variation resulted from the thermal deformation of the end faces, the equations to calculate the fluid film pressure distribution, the bearing force and the leakage rate are derived, for the fluid film both in parallel gap and in wedgy gap. The geometrical parameters of the sealing members are optimized by means of heat transfer analysis and complex method. The analysis results indicate that the shallow spiral grooves can generate hydrodynamic pressure while the rotating ring rotates and the bearing force of the fluid film in spiral groove end faces is much larger than that in the flat end faces. The deformation increases the bearing force of the fluid film in flat end faces, but it decreases the hydrodynamic pressure of the fluid film in spiral groove end faces. The gap dimensions which determine the characteristics of the fluid film is obtained by coupling analysis of the frictional heat and the thermal deformation in consideration of the equilibrium condition of the bearing force and the closing force. For different gap dimensions, the relationship between the closing force and the leakage rate is also investigated, based on which the leakage rate can be controlled by adjusting the closing force.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.     

滚筒采煤机负载的波动性分析

为了寻求滚筒采煤机正常工作时自身产生振动与冲击的原因,经过对滚筒上截齿受到的截割阻力与牵引阻力以及该两力在采煤机的牵引方向和竖直方向分力进行分析,得知两分力大小与截齿的切削厚度和旋转角度位置有关;研究了滚筒上受到的瞬时力与平均力的计算方法,推导了综合旋转角度和切削厚度的载荷波动系数的计算公式,并对所建立的公式进行了仿真模拟。结果表明:截齿数目从偶数增加1变为奇数时,载荷的波动系数的值明显减小;截齿从奇数增加1变为偶数时,载荷的波动系数不一定减小;适量的增加滚筒上同一螺旋线上截齿的数目可以有效的减小载荷的波动系数;为了提高截齿的使用寿命和可靠性以及滚筒的稳定性,减小滚筒和整个采煤机的冲击性,同一螺旋线上一周内截齿的数目应该尽量选用奇数。     

ADAPTIVE RIGID-PLASTIC MESHLESS GALERKIN METHOD AND ITS APPLICATION IN ANALYSIS OF EXTRUSION PROCESSES

Under the hypothesis of the rigid-plastic material,specific efforts are placed on the deve-lopments of the key simulation techniques of the meshless Galerkin method because of the complexity of the deformation process as well as the generality and atomization of the simulation procedures for non-steady state large deformation plastic processes,therefore,an adaptive rigid meshless Galerkin method is developed. The influence domain control method is used in the least square approximation by dynamic evaluation of the magnitude of the influence domain and the effective control of the amount and the positions of the points in the least square approximation in order to improve approxi-mation precision. The amount of the Gauss integration points in the discrete domain is maintained in a considerable magnitude in order to ensure the integration precision in the discrete domain. The length of the frictional boundary of the plastic deformation process may be getting longer when its deforma-tion is getting severe. Thus,the densities of the boundary points of some places get lower. The adap-tive boundary points setting method is employed to improve the approximation precision of the boundary points and enhance the constraint of the boundary condition by adaptive control of boun-dary point density. Some typical extrusion processes are analyzed,detail simulation results such as the deformation field,velocity field,effective strain field,effective strain rate field,the volume loss curve and load-stroke curve are obtained. The effectiveness of the method developed is demonstrated and the precision of the meshless simulation is proved by overall comparison with the results obtained by using the commercial software deform.     

DIAGNOSTICS OF FATIGUE CRACK IN ULTERIOR PLACES OF LARGER-SCALE OVERLOADED SUPPORTING SHAFT BASED ON TIME SERIES AND NEURAL NETWORKS

To improve the diagnosis accuracy and self-adaptability of fatigue crack in ulterior place of the supporting shaft, time series and neural network are attempted to be applied in research on diag-nosing the fatigue crack’s degree based on analyzing the vibration characteristics of the supporting shaft. By analyzing the characteristic parameter which is easy to be detected from the supporting shaft’s exterior, the time series model parameter which is hypersensitive to the situation of fatigue crack in ulterior place of the supporting shaft is the target input of neural network, and the fatigue crack’s degree value of supporting shaft is the output. The BP network model can be built and net-work can be trained after the structural parameters of network are selected. Furthermore, choosing the other two different group data can test the network. The test result will verify the validity of the BP network model. The result of experiment shows that the method of time series and neural network are effective to diagnose the occurrence and the development of the fatigue crack’s degree in ulterior place of the supporting shaft.     

MODELING METHOD OF 4D INFORMATION MODEL FOR COOPERATIVE DESIGN OF MECHANICAL PRODUCTS

The continuous developing features in the design of mechanical product and based on 3D entity model is aimed at, and the extension of the 4-dimensional model with the process of designing, the knowledge described model on the level of semantic understanding and summarizing the designing process and the way of discovering knowledge from multi-information model are studied. On the basis of designing the broad sensed collaborative system, through discussion of the relationship between the implicit knowledge of the users and the designing knowledge as well as commanding all the designing links, taking advantage of the way of concluding and deducting in the concept of the designers, the synthetic knowledge unit formed in the dynamic process from the conception design to the last design is schemed out, and the knowledge discovered principle in the dynamic designing process of the mechanical products and the key technology in its implementation under the milieu of network is brought forward.