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Design and Fabrication of MEMS Gyroscopes on the Silicon-on-insulator Substrate with Decoupled Oscillation Modes

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Chinese Journal of Mechanical Engineering 2010年第1期23卷 16-20页

作者： XIE Jianbing YUAN Weizheng CHANG Honglong Micro and Nano electromechanical systems laboratory Northwestern Polytechnical University Xi ＇an 710072 China

The mode coupling is a major factor to affect the precision of the micro electromechanical systems（MEMS） gyroscope. Currently, many MEMS gyroscopes with separate oscillation modes for drive and detection have been developed to decrease the mode coupling, but the gyroscope accuracy can not satisfy the high-precision demand well. Therefore, high performance decoupled MEMS gyroscopes is still a hot topic at present. An innovative design scheme for a MEMS gyroscope is designed, and in this design, the inertial mass is divided into three parts including the inner mass, the outer mass and the main frame mass. The masses are supported and separated by a set of mutually orthogonal beams to decouple their movements. Moreover, the design is modelled by multi-port-element network（MuPEN） method and the simulation results show that the mode coupling of the gyroscope between driving and sensing mode was eliminated effectively. Furthermore, we proposed a new silicon-on-insulator（SOI） process to fabricate the gyroscope. The scale factor of the fabricated gyroscope is 8.9 mV/（（~）os） and the quality factor（Q-factor） is as high as 600 at atmosphere pressure, and then, the resonant frequency, scale factor and bias drift has been test. Process and test results show that the proposed MEMS gyroscope are effective for decrease mode coupling, furthermore, it can achieve a high performance at atmosphere pressure. Furthermore, the MEMS gyroscope can achieve a high performance at atmosphere pressure. The research can be taken as good advice for the design and fabrication of MEMS gyroscope, meanwhile, it also provides technical support for speeding up of MEMS gyroscope industrialization.

关键词： micro electromechanical systems(MEMS) gyroscope silicon-on-insulator decoupled oscillation modes

A betavoltaic microbattery based on PIN diodes

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Journal of Harbin Institute of Technology(New Series) 2011年第5期18卷 71-73页

作者：臧博李晓莹乔大勇姚贤旺 Micro and Nano electromechanical systems laboratory Northwestern Polytechnical University

A betavohaic Microbattery was studied. The diode was composed of a PIN structure with an active area of 10 mm × 10 mm to collect the charge from a 10mCi Ni-63 source. An open circuit voltage of 0. 16 V and a short circuit current density of 67.6 nA/cm2 were measured. An efficiency （η） of 1.44% was obtained. The performance of device was limited by high series resistance, edge recombination and attenuation of electron in PIN diodes. It is expected to be improved by optimizing the design and using more suitable radioisotope.

关键词： betavohic microbattery PIN diodes

Three-dimensional Finite Element Analysis of the Mechanical Properties of Helical Thread Connection

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Chinese Journal of Mechanical Engineering 2013年第3期26卷 564-572页

作者： YANG Guoqing HONG Jun ZHU Linbo LI Baotong XIONG Meihua WANG Fei State Key laboratory for Manufacturing systems Engineering Xi'an Jiaotong University College of electromechanical Engineering Hunan University of Science and Technology

Conventional analytical and numerical methods for the mechanical properties of helical threads are relied on many assumptions and approximations and thus hardly yield satisfied results. A parameterized 3D finite element model of bolted joints with real helical thread geometry is established and meshed with refined hexahedral elements. The Von Mises plasticity criterion, kinematic hardening rule of materials and interfacial contacts are employed to make it possible for the suggested model be able to approach real assembly conditions. Then, the mechanical properties of bolted joints with different thread pitches, thread numbers and modular ratios are investigated, including the contact pressure distribution at joint interfaces, the axial load distribution and stress concentration in screw threads during the loading and unloading process. Simulation results indicate that the load distribution in screw threads produced by the suggested model agrees well the results from CHEN’s photoelastic tests. In addition, an interesting phenomenon is found that tightening the bolt with a large preload first and then adjusting the clamping force by unloading can make the load distribution more uniform and reduce the maximum residual equivalent stress in thread roots by up to 40%. This research provides a simple and practical approach to constructing the 3D finite element model and predicting the mechanical properties of helical thread connection.

关键词： finite element analysis thread connection load distribution stress concentration

Large deflection response-based geometrical nonlinearity of nanocomposite structures reinforced with carbon nanotubes

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Applied Mathematics and Mechanics(English Edition) 2020年第8期41卷 1227-1250页

作者： S.ZGHAL A.FRIKHA F.DAMMAK laboratory of electromechanical systems National Engineering School of SfaxUniversity of SfaxB.P W3038SfaxTunisia

This paper deals with the nonlinear large deflection analysis of functionally graded carbon nanotube-reinforced composite(FG-CNTRC)plates and panels using a finite element *** on the first-order shear deformation theory(FSDT),the proposed model takes into account the transverse shear deformations and incorporates the geometrical nonlinearity type.A C^0 isoparametric finite shell element is developed for the present nonlinear model with the description of large displacements and finite *** adopting the extended rule of mixture,the effective material properties of FG-CNTRCs are approximated with the introduction of some efficiency *** carbon nanotube(CNT)distributions,labeled uniformly distributed(UD)-CNT,FG-VCNT,FG-O-CNT,and FG-X-CNT,are *** solution procedure is carried out via the Newton-Raphson incremental *** numerical applications in both isotropic and CNTRC composite cases are performed to trace the potential of the present *** effects of the CNT distributions,their volume fractions,and the geometrical characteristics on the nonlinear deflection responses of FG-CNTRC structures are highlighted via a detailed parametric study.

关键词： carbon nanotube(CNT) functionally graded material(FGM) geometrical nonlinearity large deflection

Complex network theory-based condition recognition of electromechanical system in process industry

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Science China(Technological Sciences) 2016年第4期59卷 604-617页

作者： WANG RongXi GAO JianMin GAO ZhiYong GAO Xu JIANG HongQuan State Key laboratory for Manufacturing systems Engineering Xi'an Jiaotong University

In order to recognize the different operating conditions of a distributed and complex electromechanical system in the process industry,this work proposed a novel method of condition recognition by combining complex network theory with phase space ***,a condition-space with complete information was reconstructed based on phase space reconstruction,and each condition in the space was transformed into a node of a complex ***,the limited penetrable visibility graph method was applied to establish an undirected and un-weighted complex network for the reconstructed ***,the statistical properties of this network were calculated to recognize the different operating conditions.A case study of a real chemical plant was conducted to illustrate the analysis and application processes of the proposed *** results showed that the method could effectively recognize the different conditions of electromechanical systems.A complex electromechanical system can be studied from the systematic and cyber perspectives,and the relationship between the network structure property and the system condition can also be analyzed by utilizing the proposed method.

关键词： complex network condition recognition phase space reconstruction complex electromechanical system

Sensitivity Analysis Approach to Multibody systems Described by Natural Coordinates

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Chinese Journal of Mechanical Engineering 2014年第2期27卷 402-410页

作者： LI Xiufeng WANG Yabin State Key laboratory of electromechanical Dynamic Control Beijing Institute of Technology

The classical natural coordinate modeling method which removes the Euler angles and Euler parameters from the governing equations is particularly suitable for the sensitivity analysis and optimization of multibody systems. However, the formulation has so many principles in choosing the generalized coordinates that it hinders the implementation of modeling automation, A first order direct sensitivity analysis approach to multibody systems formulated with novel natural coordinates is presented. Firstly, a new selection method for natural coordinate is developed. The method introduces 12 coordinates to describe the position and orientation of a spatial object. On the basis of the proposed natural coordinates, rigid constraint conditions, the basic constraint elements as well as the initial conditions for the governing equations are derived. Considering the characteristics of the governing equations, the newly proposed generalized-ct integration method is used and the corresponding algorithm flowchart is discussed. The objective function, the detailed analysis process of first order direct sensitivity analysis and related solving strategy are provided based on the previous modeling system Finally, in order to verify the validity and accuracy of the method presented, the sensitivity analysis of a planar spinner-slider mechanism and a spatial crank-slider mechanism are conducted. The test results agree well with that of the finite difference method, and the maximum absolute deviation of the results is less than 3%. The proposed approach is not only convenient for automatic modeling, but also helpful for the reduction of the complexity of sensitivity analysis, which provides a practical and effective way to obtain sensitivity for the optimization problems of multibody systems.

关键词： sensitivity analysis direct differentiation method natural coordinates multibody systems

Reliability evaluation method and algorithm for electromechanical product

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Journal of Central South University 2014年第10期21卷 3753-3761页

作者：刘勇军范晋伟李云 College of electromechanical Engineering and Applied Electronics Technology Beijing University of Technology

The reliability of electromechanical product is usually determined by the fault number and working time traditionally. The shortcoming of this method is that the product must be in service. To design and enhance the reliability of the electromechanical product, the reliability evaluation method must be feasible and correct. Reliability evaluation method and algorithm were proposed. The reliability of product can be calculated by the reliability of subsystems which can be gained by experiment or historical data. The reliability of the machining center was evaluated by the method and algorithm as one example. The calculation result shows that the solution accuracy of mean time between failures is 97.4% calculated by the method proposed in this article compared by the traditional method. The method and algorithm can be used to evaluate the reliability of electromechanical product before it is in service.

关键词： reliability evaluation mean time between failures probability density function electromechanical product

DIC Based Strain and Damage Analysis of Large Scale Steel to Composite Adhesive Joints Subjected to Tension and Compression Loading

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China Ocean Engineering 2023年第4期37卷 588-597页

作者： Pankaj R.JAISWAL Rahul Iyer KUMAR Richard TRUMPER Wim DE WAELE Soete laboratory Department of ElectromechanicalSystems and Metal Engineering(EMSME)Ghent UniversityGhent 9052Belgium BAE systems London SW1Y 5ADUnited Kingdom

This paper reports an experimental study of the mechanical response to tensile and compressive force of large scale steel to composite joints adhesively bonded with a thin layer of vinylester *** one specimen,the length of the reinforcing fibres in contact with the steel substrate has been reduced by saw cutting at both ends of the *** damaged specimen and four intact specimens were subjected to quasi-static tensile testing;six specimens were used for compression *** strain distribution at the composite surface and at the steel to hardwood connection of the specimen was monitored by digital image correlation(DIC).DIC allowed identifying the onset of damage in the tensile tested joints near the interface of the composite layer and the steel-hardwood *** tensile and compression tested specimens failed due to significant peel strain concentration at the composite near the connection of steel and *** average strength of a specimen tested in compression was about 66%higher than the average strength of a specimen tested in *** strain concentration zone in the damaged specimen was away from the introduced saw *** a result the damaged and intact tensile specimens showed the same failure strength and *** specimens failed by adhesive failure between the composite-hardwood interface.

关键词： vinylester resin multi-material joint strain damage digital image correlation.

Formation of the intermediate semiconductor layer for the Ohmic contact to silicon carbide using Germanium implantation

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Chinese Physics B 2009年第10期18卷 4470-4473页

作者：郭辉王悦湖张玉明乔大勇张义门 Microelectronics School Xidian University Key Lab of Wide Band-Gap Semiconductor Materials and Devices Micro and Nano electromechanical systems laboratory Northwestern Polytechnical University

By formation of an intermediate semiconductor layer （ISL） with a narrow band gap at the metallic contact/SiC interface, this paper realises a new method to fabricate the low-resistance Ohmic contacts for SiC. An array of transfer length method （TLM） test patterns is formed on N-wells created by P＋ ion implantation into Si-faced p-type 4H- SiC epilayer. The ISL of nickel-metal Ohmic contacts to n-type 4H-SiC could be formed by using Germanium ion implantation into SiC. The specific contact resistance pc as low as 4.23×10-5Ω·cm2 is achieved after annealing in N2 at 800 ℃ for 3 min, which is much lower than that （〉 900℃） in the typical SiC metallisation process. The sheet resistance Rsh of the implanted layers is 1.5 kΩ/□. The technique for converting photoresist into nanocrystalline graphite is used to protect the SiC surface in the annealing after Ge＋ ion implantations.

关键词： SiC Ohmic contact Ge ion implantation intermediate semiconductor layer