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A Vibration-Based Method for the Measurement of Subgrade Soil Scaling Factor

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Photonic Sensors 2018年第4期8卷 375-383页

作者： Guina WANG Dakai LIANG Junfan YAN State Key Laboratory of Mechanics and Control of Mechanical Structures Nanjing University of Aeronautics andAstronautics Nanjing 210016 China College of Mechanical and Electrical engineering Soochow University Suzhou 215021 China School of Earth Sciences and Engineering Nanjing University Nanjing 210093 China

The subgrade soil scaling factor （SSSF） shows the basic properties of soil such as stiffness, gravimetry, density, and particle distribution, which are essential for disaster prediction and geotechnical engineering activities. In this paper, methods used for soil properties analysis are firstly summarized, and then a fiber Bragg grating （FBG） sensing technology is introduced. In order to acquire the properties and mechanical characteristics of soil accurately, a vibration-based method is presented, and an experiment for judging the properties of soil is conducted. As for the experiment, an FBG sensor is adhered to the upside of the vibration rod to measure its fundamental frequency. The rod vibrates freely at different-depth level of soil, and the changed data of wavelength from the FBG sensor are carefully collected. The Winkler spring model is used to analyze the relationship between the fundamental frequency and stiffness of soil. The results of this experiment suggest that data collected from FBG sensor can reflect vibration situation clearly and quantitatively. Thus the SSSF value can be calculated from the frequency-stiffness equation. The experimental results are almost identical with the theoretical derivation results. This confirms that the method presented in the paper can determine the SSSF effectively.

关键词： Vibration sensor cantilever beam Winkler reaction spring model subgrade soil scaling factor

Measurement of Young's Modulus and Poisson's Ratio of Thermal Barrier Coatings

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Chinese Journal of Aeronautics 2005年第2期18卷 180-184页

作者：齐红宇周立柱杨晓光 College of Jet Propulsion Beijing University of Aeronautics and Astronautics Beijing 100083China

In gas turbines, thermal barrier coatings （TBCs） applied by air plasma spraying are widely used to lower the temperature of hot components. To analyze the characteristics of TBCs such as residual stress, bond strength, fracture toughness, and crack propagation ratio, the Young＇s modulus and Poisson＇s ratio are important parameters. For TBC is a brittle and thin film, it is desirable to evaluate those properties while the coatings are bonded to a substrate. An atmospheric plasma spray MCrAIY bond coat and Yttria stabilized zirconia （YSZ） top coat are deposited onto a nickel-base superalloy GH150 substrate. The Young＇s modulus and Poisson＇s ratio are measured by cantilever beam bending with NDI. The method will be developed to test the Young＇ s modulus and Poisson ratio of other multilayer systems.

关键词： thermal barrier coatings cantilever beam Young' s modulus Poisson' s ratio

Theory of Flexural Shear, Bending and Torsion for a Thin-Walled beam of Open Section

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World Journal of Mechanics 2024年第3期14卷 23-53页

作者： David W. A. Rees Abdelraouf M. Sami Alsheikh College of Engineering and Design Brunel University Uxbridge UK

Aspects of the general Vlasov theory are examined separately as applied to a thin-walled channel section cantilever beam under free-end end loading. In particular, the flexural bending and shear that arise under transverse shear and axial torsional loading are each considered theoretically. These analyses involve the location of the shear centre at which transverse shear forces when applied do not produce torsion. This centre, when taken to be coincident with the centre of twist implies an equivalent reciprocal behaviour. That is, an axial torsion applied concentric with the shear centre will twist but not bend the beam. The respective bending and shear stress conversions are derived for each action applied to three aluminium alloy extruded channel sections mounted as cantilevers with a horizontal principal axis of symmetry. Bending and shear are considered more generally for other thin-walled sections when the transverse loading axes at the shear centre are not parallel to the section = s centroidal axes of principal second moments of area. The fixing at one end of the cantilever modifies the St Venant free angular twist and the free warping displacement. It is shown from the Wagner-Kappus torsion theory how the end constrained warping generates an axial stress distribution that varies with the length and across the cross-section for an axial torsion applied to the shear centre. It should be mentioned here for wider applications and validation of the Vlasov theory that attendant papers are to consider in detail bending and torsional loadings applied to other axes through each of the centroid and the web centre. Therein, both bending and twisting arise from transverse shear and axial torsion applied to each position being displaced from the shear centre. Here, the influence of the axis position upon the net axial and shear stress distributions is to be established. That is, the net axial stress from axial torsional loading is identified with the sum of axial stress

关键词： Thin Wall Theory cantilever beam Open Channel Section Principal Axes Flexure Transverse Shear Torsion Shear Centre Shear Flow Warping Fixed-End Constraint

Analysis and Design for a Micro Mechanical Optical Switch

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Journal of Semiconductors 2001年第7期22卷 837-840页

作者：贾玉斌陈良惠李玉璋中国科学院半导体研究所国家光电子器件工程研究中心北京100083

The mechanical and electric characteristics of a cantilever beam micro opto mechanical switch are studied theoretically,with which the dependence of the flexion on the applied voltage is derived,as well as the formula of the threshold *** applied voltage,having no connection with the width of the beam,is in inverse proportion to the square of the beam's *** deflection at the beam's tip cannot exceed 1/3 of the distance between two adjacent *** results are the basis of the switch design and development.

关键词： MEMS optical switch cantilever beam threshold voltage

Fabrication and Simulation of an Electromagnetic Microrelay

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Journal of Semiconductors 2002年第12期23卷 1298-1302页

作者：张宇峰李德胜哈尔滨工业大学自动化测试与控制系哈尔滨150001 北京工业大学机电工程学院北京100022

The fabrication and simulation of an electromagnetic microrelay are presented based on micro electromechanical systems (MEMS) *** microrelay dimensions of about 4mm×4mm×0 5mm are fabricated with the common technique of *** with the traditional relays,a planar coil is substituted for a solenoid coil to favor the MEMS ***,a bi supporter cantilever beam with high sensitivity is fabricated to act as the movable electrode of the *** calculations and simulations are also carried out with respect to the electromagnetic force yielded by the exciting electromagnetic *** structure and parameters concerning the electromagnetic microrelay can be optimized using the results.

关键词： electromagnetic microrelay MEMS micromachining planar coil cantilever beam

An active temperature compensated fiber Bragg grating vibration sensor for high-temperature application

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Journal of Measurement Science and Instrumentation 2020年第4期11卷 397-404页

作者： CHEN Bao-jie JIA Ping-gang QIAN Jiang FENG Fei HONG Ying-ping LIU Wen-yi XIONG Ji-jun Key Laboratory of Instrumentation Science and Dynamic Measurement (North University of China) Ministry of EducationTaiyuan 030051China Science and Technology on Electronic Test&Measurement Laboratory North University of ChinaTaiyuan 030051China

An active temperature compensated fiber Bragg grating(FBG)vibration sensor with a constant section cantilever beam is proposed for the simultaneous measurement of temperature and vibration,and the sensor is verified by a temperature compensation feedback *** high-temperature vibration sensor is composed of a quartz cantilever beam and a femtosecond Bragg *** feedback control demodulation system of active temperature compensation can adjust the laser wavelength to stabilize the grating offset point and realize simultaneous measurement of temperature and *** this basis,the performance of the sensor is tested and analyzed within the range of 20-400℃by setting up a high-temperature vibration test *** experimental results show that the sensitivity of the sensor is about 132.33 mV/g,and the nonlinearity is about 3.33%.The sensitivity between the laser wavelength and temperature is about 0.01307 nm/℃.In addition,the active temperature compensated fiber Bragg grating vibration sensor has the advantages of a simple structure,stable performance,easy demodulation and high ***,the sensor can achieve high temperature vibration signal monitoring and has good practical application value.

关键词： fiber Bragg grating(FBG) vibration sensor active temperature compensation cantilever beam feedback control

The Optimization Design and Simulation Analysis of Actuator Output Mechanism Stiffness

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The Optimization Design and Simulation Analysis of Actuator ...