ResearchonWorkingStateMonitoringSystemofCoalMineMachinery

ZHANGWendong,XUEChenyang
(Key Laboratory of Instrumentation Science & Dynamic Measurement of Ministry of Education, North University of China Taiyuan, 030051, China)

AbstractCoal is an important fossil energy in today's society，and coal mine machinery is a key equipment for coal mine enterprises to realize mechanization. To meet security demand, its working state should be monitored carefully, which can produce an important economic value. Main faults of coal mine machinery equipment, their generation causes and types of faults manifestation formation are reviewed in this paper. The methods and characteristics of mechanical fault diagnosis are also summarized by judging whether the coal mine machinery needs to be stopped or the signal acquisition and fault diagnosis are real-time. The characteristics and practicability in coal mine of different wireless network transmission technologies and different micro energy technologies are also analyzed. Simultaneously, a kind of monitoring system is proposed to on-line automatically monitor and to diagnose the coal mine machinery equipment, based on the deficiency of current monitoring system of coal mine machinery. The self-power supply of information acquisition and transmission system for working state of coal mine machinery can be realized in this system in terms of micro energy technology. In addition, Zigbee and GPRS are combined to accomplish the signal transmission in this system. This system can develop the monitoring system in the future.

Keywordscoal; energy; automation; coal mine machinery; working state monitoring system; micro energy technology; wireless sensor network

EquivalentModelandDampingPerformanceofOptimizedCompoundMentalDamper

HEHaoxiang,WANGXiaobing,ZHANGXiaofu
(Beijing Key Laboratory of Earthquake Engineering and Structural Retrofit, Beijing University of Technology Beijing, 100124,China)

AbstractThe traditional metal dampers have the disadvantages such as higher yield point and inadequate adjustability. To overcome these deficiencies, a compound mental damper which comprises the low yield point steel plates and common steel plates is presented. The optimization objectives including “maximum rigidity” and “full stress state” are proposed to obtain the optimal shape of compound mental damper. The numerical simulation results show that the compound mental damper has the advantages such as the full hysteresis performance and uniform stress state, and the integral yield point can be regulated. In view of the mechanical characteristic of the compound metal damper, the equivalent model of eccentric cross bracing is established, and the approximate analytical solution of the yield strength and the yield displacement is proposed. The nonlinear simulation analysis is carried out for the overall aseismic capacity of the frame structures with the compound mental damper. It is verified that the compound mental damper has better energy dissipation capacity and more superior seismic performance, especially for the damper with optimized shape.

Keywordsmetal damper; seismic control; low yield point steel; topology optimization; full stress

PredictingModelofFluidInerterBasedontheQuantumGeneticSupportVectorMachine

SHENYujie,CHENLong,LIUYanling,YANGXiaofeng,ZHANGXiaoliang,WANGRuochen
(School of Automotive and Traffic Engineering, Jiangsu University Zhenjiang, 212013, China)

AbstractIn the light of the dynamic characteristics of an inerter, a new fluid inerter is designed. First, the bench tests are carried out on the hydraulic serve exciting platform and the nonlinearities and their effect on the output force are also analyzed. The predicting model of the fluid inerter by the support vector machine is established because the accurate dynamic model of fluid inerter is hard to expressed by analytical methods. Then, the force output of the fluid inerter at different frequency and displacement is investigated, and the variance of the radial basis function and the punishment factor are optimized by means of quantum genetic algorithm. Finally, the comparisons between the results obtained from the predicting model and those of the experiments show that the predicting results are in good agreement with those obtained by the tests. The optimal predicting model has a higher precision, and the amplitude is decreased by 61.36%. The predicting model successfully provides a new method to study the dynamics behavior of the fluid inerter.

Keywordsfluid inerter; quantum genetic algorithm; support vector machine; predicting model

KnockDetectionUsingVariationalModeDecomposition

BIFengrong,LIXin,MATeng
(State Key Laboratory of Engines, Tianjin University Tianjin, 300072, China)

AbstractThe empirical mode decomposition (EMD) method has inherent defects because of a recursive decomposition. This paper introduces variational mode decomposition (VMD) into knock detection field, based on variational principle. Compared with the EMD, the VMD has better efficiency and accuracy, and more robust, which is better for knock detection in the vibration signal with strong background noise. In this case, this paper proposes an adaptive selection of VMD’s level number using the center frequency of different components, because the VMD method needs presetting the numbers of modal components. Decomposing a signal by the VMD in a low level, and increasing the decomposition level one by one are available till the center frequency of different components meet the predefined threshold, in whichthe best decomposition results can be obtained. The method is proved by the verification and comparison of experimental data.

Keywordsengine; knock; vibration signal; fault diagnosis; variation mode decomposition

AnalysisofConsistentStimulusofRoadRoughnessonVehicle-BridgeCouplingNonstationaryRandomVibrations

GUIShuirong1,CHENShuisheng1,WANShui2
(1.Department of Civil Engineering and Architecture, East China Jiaotong University Nanchang, 330013, China)(2.School of Transportation, Southeast University Nanjing, 210096, China)

AbstractThe vibration responses of a 3D random model for a vehicle-bridge system subjected to running vehicle at nonconstant speed are resolved by pseudo excitation method (PEM) based on a consistent stimulus of road roughness. Taking multipoint coherent road roughness excitation into condition, a new 3D random vibration model for vehicle-bridge systems is proposed. In the vehicle-bridge coupling model, the bridge is modeled as a beam-shell solid element, the vehicle is simplified as a 3D freedom model with nine degrees and the load caused by the road roughness is equivalent to a pseudo excitation load. The model is resolved by a precise integration method (PIM), and the accuracy of results is verified through comparing with the results of a Monte-Carlo method. Taking one highway beam bridge as an example, different point dynamic responses of the bridge subjected to uniformly accelerating vehicle have been researched. The results prove the accuracy and feasibility of the vehicle-bridge coupling random vibration model which has been proposed in the paper. The vehicle speed is the most fact which leads to a peak displacement and a peak acceleration at mid-span with the same road roughness excitation. There is more large resonance frequency region when the vehicle runs on bridge with a nonconstant speed than a constant one. The peak displacement and peak acceleration at mid-span of growth appears fast followed by slow when the vehicle speed increases gradually.

Keywordsvehicle-bridge coupling system; nonstationary random vibration; pseudo excitation method (PEM)； consistent stimulus of road roughness

DamageIdentificationforContinuousGirderBridgeBasedonWaveletPacketSampleEntropy

SUNZengshou1,LIXiaopeng2,HANPeiyan1,LOUWenshuai1
(1．School of Civil Engineering，Zhengzhou University Zhengzhou, 450001， China)(2．The Second Branchu，Henan Provincial Communications Planning & Design Institute Co., Ltd. Zhengzhou, 450002, China)

AbstractIn order to reduce the number of sensors arranged in current bridge detection, the wavelet packet decomposition and sample entropy are combined. A novel method detecting and identifying the structural damages of continuous girder bridge by dynamic response signal of single point has been discussed and studied. A novel damage identification index and method of continuous girder bridge has been proposed. In applications, the wavelet packet transform is used to decompose and reconstruct the acceleration response signal of bridge under moving load. The sample entropy values of reconstructed signal have been calculated. Moreover, the sample entropy of wavelet packet transform with different logarithmic acceleration energy has been established to act as a damage identification index. Its applicability and correctness are verified by a three-span continuous girder bridge with variable cross sections. Noise robustness of index is alsoanalyzed. The research results show that the index and method proposed in this paper can identify the damage location and extent by analyzing the acceleration response signals of any points on bridge, which is not sensitive to the noise.

Keywordsdamage identification; wavelet packet transform; sample entropy; dynamic response; continuous girder bridge

BoltLoosenessDetectionunderChangingTemperatureConditionsUsingIndependentComponentAnalysis

XIEXueduo,XIAOLi,QUWenzhong
(Department of Engineering Mechanics, Wuhan University Wuhan, 430072, China)

AbstractDamage detection technology based on guided wave relies on comparing response signals with baseline records. However, the temperature variation can also produce large changes in guided wave signals, thereby causing a false alarm of damage detection. For eliminating the influence of temperature variation in the process of damage detection, independent component analysis (ICA) method is developed to process guided wave response signal. As a blind source separation algorithm, ICA can extract independent unknown source components from mixed signals. Therefore, the ICA method can separate the source signals of the guided waves from the mixed signals disturbed by the temperature, and achieve the purpose of eliminating the interference of temperature changes. In this paper, the experiment of bolt looseness damage detection is made in the environment of temperature variation. The collected signals are utilized in damage localization estimation after processing by ICA. It shows a good result for bolt looseness localization, which indicates that this method is robust to the temperature variation exhibited in damage detection based on guided wave.

Keywordsguided wave; bolt looseness; damage detection; temperature variation; independent component analysis

ARollingBearingFaultDiagnosisApproachBasedonImprovedMultiscaleFuzzyEntropy

ZHENGJinde，DAIJunxi，ZHUXiaolong，PANHaiyang，PANZiwei
(School of Mechanical Engineering, Anhui University of Technology Maanshan, 243032, China)

AbstractThe key of rolling bearing fault diagnosis is the extraction of sensitive fault features. Multiscale fuzzy entropy (MFE) is an effective analysis method for complexity measurement of time series and has been used for fault features extraction from rolling bearing vibration signals. Considering the defects existed in the MFE coarse graining , its process is replaced by sliding average and then an improved MFE algorithm is proposed in this paper. It is also compared with MFE by using simulation signal analysis. In this case, a new fault diagnosis method for rolling bearing is proposed based on the improved multiscale fuzzy entropy and support vector machine. Finally, the proposed fault diagnosis method is applied to data analysis of rolling bearing experiment by comparing with the traditional MFE method, and the analysis results verify the effectiveness and superiority of the proposed method.

Keywordsmultiscale fuzzy entropy; modified multiscale fuzzy entropy; rolling bearing; fault diagnosis

DesignandExperimentofTestingSystemofCharacteristicsofLinearUltrasonicMotor

FENGSen,SHIYunlai，ZHANGJun,LOUChengshu
(State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics Nanjing, 210016, China)

AbstractAiming at the problems of low precision, single function and low degree of automation in the existing testing system of characteristics of linear ultrasonic motor, a test system of characteristics is designed for measuring mechanical and transient characteristics of linear ultrasonic motor, which is mainly composed of motor drive module, data acquisition module, test control and data processing module. The motor drive module mainly takes the STM32F429 micro-controller as a core controller, which can conveniently realize multi-parameter adjustment of its drive signal. The data acquisition module is mainly composed of a displacement sensor, a tension-compression sensor and a high speed data acquisition card. The test control and data processing module are mainly realized by a computer. The mechanical and transient characteristics of the “butterfly” type linear ultrasonic motor are tested by using the system. The results show that the system can well achieve the measurement of characteristics of linear ultrasonic motor, and can be conveniently operated and easily expanded.

Keywordslinear ultrasonic motor； mechanical characteristics； transient characteristics； testing system

CharacteristicsAnalysisofLandingBufferintheTrussTypeMarsLander

CHENChuanzhi1，WEIJun1，CHENJinbao1，NIEHong2，ZHENGGuang2，YUANYingnan1
(1.College of Aeronautics, Nanjing University of Aeronautics and Astronautics Nanjing, 210016 , China)(2.College of Aerospace Engineering, Nanjing University of Aeronautics and Astronautics Nanjing, 210016, China)

AbstractLanding buffer is one of key parts to realize a soft landing on planet. Its cushioning performance is directly related to the success or failure of the soft landing on the planet surface. According to the given model of the mars lander, a reasonable simplified model of the lander is established in a three dimensional modeling software. In order to improve the analyzing accuracy of of the impact response in this landing process, the buffer performance of the lander is analyzed by the method of transient dynamics using a finite element software Patran/Dytran (MSC company). The simulation results are in agreement with the experimental data. Therefore, it is feasible to use the truss type mars lander. The simulation results and experimental data also provide references for future Mars exploration.

Keywordssoft landing; buffer mechanism; transient dynamics; finite element simulation

GasTurbineStateRecognitionBasedonFuzzyIntegralTechnologyResearch

CUIJianguo1，LIUYao1，YUMingyue1，JIANGLiying1，WANGJinglin2,JIANGXiuhong3
(1.School of Automation, Shenyang Aerospace University Shenyang, 110136, China)(2.AVIC Aviation Key Laboratory of Science and Technology on Fault Diagnosis and Health Management Shanghai, 201601, China)(3.School of Electronic and Information Engineering, Shenyang Aerospace University Shenyang, 110136, China)

AbstractIt is difficult to identify the state of a marine gas turbine because of the complicated structure and poor working environment. This paper puts forward a new method combining the kernel principal component analysis (KPCA) and fuzzy integral. First, the KPCA method is adopted to extract nine state characteristics parameters from the kernel principal components, such as the high pressure rotor speed, low pressure rotor speed, turbine exhaust temperature and casing vibration, to create a feature vector space. Then, the nuclear principal eigenvector was created based on the generalized regression neural network (GRNN) for an Elman neural network identification model to identify the gas turbine condition. Finally, the fuzzy integral is used to calculate the gas turbine state according to the result of two kinds of state recognition for policy makers. Research shows that the proposed method can effectively identify the gas turbine health and fault state of the ships by combining the key components, and has very good practical application value.

Keywordsship with gas turbine； kernel principal component analysis； neural network； fuzzy integral； state recognition

TheCharacteristicsIdentificationofChordMeasurementofTrackSurfaceDefectsBasedUponSingularComponentKurtosis

YINHua1,2,ZHUHongtao2
(1. School of Software, Jiangxi Agricultural University Nanchang, 330045, China) (2.School of Mechanical & Electrical Engineering, Nanchang University Nanchang, 330096, China)

AbstractChord measurement is a widely-used method of inspecting track irregularity at present. Considering the singular characteristics of rail track surface defects, a new method is proposed to identify these defects on the basis of multi-chord theory by analyzing their responses to mid-chord model. Then, the test data are separated by singular value decomposition, since the surface damage is enhanced when the track irregularity amplitude gain is reduced by proper combination of chords. Thus, the rail track surface defects characteristics and their positions are extracted through the sliding kurtosis sequence. Theoretical simulation and test results show that this approach is able to get rail track surface defects information which is hidden in chord measured value. The proposed method is suitable for engineering application.

Keywordstrack surface defects; midpoint chord model; singular value decomposition; sliding kurtosis

TheCouplingAnalysisofSpaceLighttoOpticalFiberinMicroVibrationEnvironmentandtheCompensationMethod

HUQinggui1,LIChengzhong2
(1.Modern Education Technology Center, Neijiang Normal University Neijiang, 641100, China)(2.School of Information Science and Technology, Southwest Jiaotong University Chengdu, 610000, China)

AbstractIn order to reduce the influence of micro vibration on the coupling of spatial light to fiber, its coupling characteristics are studied and a new kind of conical receiver is put forward. Both the total reflection characteristics and the coupling performance of the tapered receiver are discussed theoretically. The result shows that, in the micro vibration environment, the coupling efficiency of the new tapered receiver is higher than that of the conventional fiber receiver. Then, the experiments present that when the amplitude increases from 0 to 280 μrad, for the ordinary optical fiber receiver, the coupling efficiency decreases rapidly from 95% to 10%. On the other hand the efficiency factor only drops to 55% with the new tapered optical fiber receiver. The results show that, under the condition of micro vibration, the new receiver can effectively improve the coupling efficiency.

Keywordsmicro-vibration; conical structure; space optical communication; coupling efficiency

SynchronousConstructionNetworkedControlSystemBasedonImprovedSmithPredictor

BIANYongming1,YANGMeng1,FangXiaojun1,CUIWeiwei2
(1.School of Mechanical Engineering, Tongji University Shanghai, 201804, China)(2.Electrical and Mechanical Department, Shanghai TongXin Mechatronic Technology Co., Ltd. Shanghai, 200949, China)

AbstractDepending on the principle of synchronous construction networked control system (NCS), the effect of time-variant, random and uncertain network delay on the synchronization error is analyzed. Then, the blemish and disadvantage of traditional Smith predictor, which is used for synchronous control of the multiple controlled plants, are also analyzed. An improved Smith predictor is proposed to realize multiple Smith predictive compensation for the network delay, controlled plants with pure delay and the controller of synchronization error, eliminating the delay of feedback path from the control system totally. The prediction model does not contain network delay, so it does not have to be estimated or measured. With the synchronous NCS of segment erector for shield based on CAN (controller area network), the simulation comparison between the conventional PID (proportion integral derivative) networked control and the one based on improved Smith predictor is carried out, and the experiments are performed to evaluate the performance of the proposed method. Finally, the results show that the conventional PID networked control and the one based on improved Smith predictor behave with synchronization error of -3～3 mm, -1.5～1.5 mm respectively. The latter can improve the performance of the synchronous construction networked control system significantly.

KeywordsSmith predictor; multiple controlled plants; network delay; synchronization error; networked control system

FiniteElementModelUpdatingUsingStrainModeandGeneticAlgorithm-BasedMethod

ZHANMing1，GUOQintao1，YUELin1，ZHANGBaoqiang2
(1.College of Mechanical and Electrical Engineering, Nanjing University of Aeronautics and Astronautics Nanjing, 210016, China)(2.College of Aeronautics and Astronautics, Xiamen University Xiamen, 361005, China)

AbstractBased on strain modal assurance criterion, a model updating method is proposed. Strain modal assurance criterion, on one hand, is a satisfactory approach to evaluate the correlation between finite model simulation and experiment. On the other hand, strain modal assurance criterion offers global frequency error and local mode shape error for model updating. The basic theory of strain mode and finite element model updating is briefly introduced. Then, take a stiffened structure as example, the process of model updating based on strain mode is illustrated. Firstly, strain modal frequencies and mode shapes are obtained from simulation and experiment, respectively. And then, modal assurance criterion of strain modes and error of modal frequencies are calculated. The objective function for model updating is constructed based on above errors and unknown parameters are estimated utilizing genetic algorithm. Finally, the estimated parameters are substituted into the finite model to validate the accuracy and effectiveness. The results show that: the proposed method can reproduce the response in the updating domain and have an excellent ability to predict the response outside the updating domain.

Keywordsstrain mode; modal assurance criterion; model updating; genetic algorithm; stiffened structure

MillingChatterOnlineMonitoringMethodBasedonEnergyAccountingPercentage

LIHongkun1,ZHOUShuai1,WEIZhaocheng1,ZHAOMing2,DAIYuebang1
(1.School of Mechanical Engineering, Dalian University of Technology Dalian, 116024, China)(2.Technology Center Process Research Laboratory, Shengyang Liming Aeroengine Corporation Ltd. Shenyang, 110043, China)

AbstractIn the finishing stage of thin-walled parts, due to the tool overhang, the workpiece stiffness is low, so it is easy to deform during machining and cause flutter. Therefore, a reliable standard is needed to monitor the machining state and determine whether the machining parameters are reasonable. In this study, the sound pressure data including chatter phenomenon are collected and analyzed. The time domain effective value and power spectrum of frequency domain are analyzed. The characteristics of different states are compared, and these characteristics are used as the basis for monitoring. When the flutter occurs, the energy concentration shifts at the frequency band. After the wavelet packet decomposition, the characteristic quantities reflecting the feature are constructed. The wavelet transform time-frequency map is used as the state judgment basis, and the correlation threshold is set up by off-line analysis. After setting multiple standards to meet the requirements of the time domain effective value and the frequency domain energy ratio threshold, the eigenvalues are calculated and the processing status is judged. The flutter phenomenon can be identified accurately, and the acoustic pressure signal can reflect the flutter characteristics. After the threshold setting, the invention can provide a judgment standard for the on-line monitoring of the subsequent processing and avoid the damage to the workpiece or the machine tool due to the unreasonable selection of the processing.

Keywordschatter; acoustic pressure; energy accounting percentage; online monitoring; wavelet transform

VibrationCharacteristicsforUnbalanceofTurbomachineryShaftingwithThree-RotorandFour-Support

SHENYiping，BINGuangfu，WANGGang，LIXuejun
(Health Maintenance for Mechanical Equipment Key Laboratory of Hunan Province, Hunan University of Science and Technology Xiangtan, 411201, China)

AbstractIn the light of the unbalanced vibration in the shafting with three-rotor and four-support such as the steam turbine unit and compressor unit, the vibration characteristics of each rotor with mode shape unbalance is developed. First, the dynamics finite element model of shafting with three-rotor and four-support is built. The first and second bending mode shape unbalanced excitations are applied to each rotor of shafting respectively, and the shaft response analysis of shafting are taken. The relationship between the unbalanced excitation type of each rotor and shafting response is confirmed. Then, the rotor simulation experiment rig for shafting with three-rotor and four-support is designed to investigate the support responses and analyze the resonance points, magnitude- frequency and phase-frequency characteristics due to unbalanced excitation. It shows that the vibration characteristics of shafting with added unbalance inside of rotor is determined collaboratively by mode shape and excitation type. Additionally, the overhung rotor vibration characteristics is obvious. It is beneficial to suppress the unbalance vibration fault of this kind of shafting with three-rotor and four-support.

Keywordsmode shape unbalance; shaft response; vibration experiment; three-rotor and four-support shafting

RandomVibrationFatigueLifeAnalysisBasedonNonlinearCumulativeDamage

WANGHu，WANGKe，ZHAOLiru
(Institute of Vibration Engineering Research，Nanjing University of Aeronautics and Astronautics Nanjing, 210016，China)

AbstractIt is a complex problem to predict the fatigue life of structures subjected to random loads. The simplest and most widely used damage model is the Miner's linear damage criterion. However, the application of this criterion often leads to the risky life prediction. Nonlinear cumulative damage theory takes into account the effect of loading sequence on fatigue life, with higher accuracy, but it is cumbersome and can not be used for frequency domain life calculation. In this paper, a modified algorithm of frequency domain fatigue life prediction based on nonlinear cumulative damage is presented. The accuracy of the algorithm is verified by simple test. For a stiffened plate structure with accurate dynamics modeling, the validity of the method and the engineering usability are proved.

Keywordsrandom vibration; frequency domain method; nonlinear cumulative damage; damage curve method; life modification

DurabilityFractureTestsforSteeringKnuckleArmofHeavyTruckonEnhancementRoads

MENYuzhuo1,YUHaitao2,YUHaibo1
(1.School of Automotive Engineering, Jilin Engineering Normal University Changchun, 130012, China)(2.Laboratory Equipment Management Center, Harbin Normal University Harbin, 150025, China)

AbstractIn order to research the fracture of cone root of steering knuckle arm occurring at the phase of durability test on the enhancement road of proving ground, and consider the characteristics of material structure and process assembly precision, the fracture model of steering arm is analyzed in detail. The full bridge strain gauge is pasted in the vicinity of fracture and the testing sensor linked to the steering system is equipped, thus the bending strain of the broken portion, lateral acceleration and displacement of steering tie rod and other load data are collected. The hysteresis loop curve equation of cyclic stress-strain and Neuber formula is applied to convert the nominal stress to the local stress-strain cycle response at the fracture location. According to Manson-Coffin equation, impact of mean stress on fatigue damage is corrected. The analysis and calculation results show that the material characteristic of steering arm meets the technical conditions, but the taper and surface finish of steering arm cannot meet the design precision in drawing, the contact area of steering arm and steering knuckle can only reach 30%, local high stress is caused at the steering knuckle and cone root of steering knuckle arm, and bending low cycle fatigue fracture will generate.

Keywordsvehicle; strength; reliability; steering knuckle arm; stress; process; fatigue

ParametricAnalysisofWind-InducedResponsesofTypical500kVSingle-CircuitTransmissionTower

ZHANGQinghua
(School of Civil Engineering and Communication, North China University of Water Resources and Electric Power Zhengzhou, 450000, China)

AbstractThe finite element modal analysis of a typical single-circuit 500 kV high-voltage transmission tower is carried out. Then, the computing method based on the non-steady wind forces in frequency domain is applied to the wind-induced responses calculation of the transmission tower, the effects of main frequency domain parameters such as number of modes numbers, cross terms of modes and damping ratio of structures on the response are discussed in detail. The results show that for the superstructure of tower, the calculation accuracy of displacement response can be ensured only by taking into account the bending (x,ydirection) and torsional (zdirection) first order integral mode shape. And the mode numbers have great influence to the calculation of acceleration responses, the accelerations of transmission tower are monotonously increasing with the mode numbers. And the contribution for base bending moments mainly comes from the first bending mode. Furthermore，the wind-induced responses of transmission tower are sensitive to the structural damping ratio, especially, the resonant responses obviously decreased with the increasing of damping ratio, but the change of damping ratio has little influence on low frequency part of responses. What is more, the cross terms of modes can be neglected for the responses calculation of typical single-circuit transmission tower in frequency domain.

Keywordstransmission tower; wind-induced response; parametric analysis; frequency-domain analysis

DesignofBroadbandVibrationAbsorberandCurrentControlMethod

SONGWeizhi1,YAOYongyu1,ZHAOHaijun1,2,ZHAOHongxia1,YUESuilu1,CHENZhiyong1,
(1.College of Mechanical Engineering, Luoyang Institute of Science and Technology Luoyang, 471023, China)(2.College of Automotive and Transportation Engineering, Tianjin University of Technology and Education Tianjin, 300222, China)

AbstractPassive dynamic vibration absorber (PDVA), whose structural parameters can not be adjusted and vibration frequency band is single, is not suitable for broadband vibration. To solve the above problem, first, the magnetorheological elastomer (MRE) is used as the stiffness element to design an adaptive dynamic vibration absorber (ADVA). Second, the composition and MR effect of MRE are introduced and analyzed. Then, the current control method in the process of dynamic vibration absorber is proposed to eliminate the new resonance phenomenon which is caused by the addition of a vibration absorber to the controlled system. Finally, the simulation and experiment results show that the design can broaden the vibration frequency band to 11.37 Hz. At the same time, the new resonant peak of the controlled system is eliminated effectively by the proposed control method.

Keywordspassive dynamic vibration absorber; magnetorheological elastomer; resonance peak; effective band; current control

FaultSignalExtractionMethodofRollingBearingWeakFaultBasedonLMD-MS

WANGZhijian,WUWenxuan,MAWeijin,ZHANGJiping,WANGJunyuan,LIWeiwei
(College of Mechanical and Power Engineering, North University of China Taiyuan, 030051,China)

AbstractIn the practical case, the early fault signals of bearings are weak which is difficult to extract from strong noise. So, when a mask method is introduced into local mean decomposition (LMD), a method for extracting weak fault of rolling bearings based on mask signal method and LMD has been proposed in this paper. Because there is a mode mixing phenomenon when LMD decomposes the product function (PF) components in the noise background, it is difficult to distinguish which fault frequency is true or false. Furthermore, the mask signal method introduced to the decomposed PF components, alleviates the mode mixing phenomenon, and it can extract the real fault frequency. According to the analysis of the actual fault signals of rolling bearings, the kurtosis value has increased 8 times at the fault frequency using the mask signal method and LMD to process the fault signals with noise, and the signal’s noise ratio has increased 19.1%. At the same time, the fault signals have been extracted.

Keywordsstrong noise; bearing fault; mask method; local mean decomposition(LMD); fault diagnosis

MethodofIncipientFaultDiagnosisofBearingBasedonAdaptiveOptimalMorletWavelet

ZHUXiaoyan,WANGYongjie,ZHANGYuqi,YUANJingyi
(School of Energy Power and Mechanical Engineering, North China Electric Power University Baoding, 071003, China)

AbstractThe early stage weak impulsive fault feature is so weak that it is always covered by environmental noise, which increases the fault diagnosis difficulty of rolling bearing. Aiming to this problem, a new diagnosis method based on adaptive optimal Morlet wavelet transform is proposed. Firstly, The core parameter of Morlet wavelet transform is calculated by particle swarm optimization (PSO) adaptively, which guarantees optimal Morlet based wavelet as well as wonderful band-pass filter performance; Secondly, in order to improve signal-to-noise ratio, optimal Morlet wavelet is used to filter incipient fault signal of rolling bearing; Finally, optimal Morlet wavelet filtered signal is analyzed by envelope spectrum, and the fault location of rolling bearing is extracted by contrasting the major frequency with the fault frequency of rolling bearing. The analysis results of simulated signal and measured signal show that the proposed method is able to extract the fault impulse signal.

KeywordsMorlet wavelet transform; rolling bearing; incipient fault diagnosis; feature extraction

AnalysisofMeshingForceofHelicopterTailDriveSystemDuringRelativePositionChangesofShafting

JIANGLingli，YINDaoxuan，LIXuejun，FENGHeying
(Hunan Provincial Key Laboratory of Health Maintenance for Mechanical Equipment, Hunan University of Science and Technology Xiangtan, 411201, China)

AbstractThe shafting structure of helicopter transmission system is complex, then its relative position changes will affect the transfer characteristics of the whole transmission system. Using tail drive system of a certain helicopter - a pair of spiral bevel gears system with perpendicular shafts as the study object, the variation characteristics of the gear pair meshing force under relative position changes of shafting are studied. By establishing a dynamics model of the pair of spiral bevel gears system with relative position changes of shafting, and combining with the multi-body dynamics software, the variation characteristics of the gear pair meshing force are simulated and analyzed. The results show that the average meshing force decreases with the increase of offset position changes, and increases with the increase of inclined angle position changes. The inclined angle position changes have more serious influence on gear meshing characteristics than the offset position changes. This research can provide a theoretical basis for condition monitoring of helicopter tail drive system, and it is important to improve the stability of the helicopter transmission system and ensure its safe and efficient operation.

Keywordshelicopter tail drive system; relative position change of shafting; meshing force; condition monitoring

StructureOptimizationandExperimentofDouble-FeetPiezoelectricLinearActuator

ZHONGXiangqiang1,2,ZHANGBenxue2,HUANGWeiqing1,3,SUNMengxin1
(1.State Key Laboratory of Mechanics and Control of Mechanical Structures,Nanjing University of Aeronautics and Astronautics Nanjing, 210016, China)(2. School of Mechanical & Automotive Engineering, Anhui Polytechnic University Wuhu, 241000, China)(3. School of Mechanical & Electric Engineering, Guangzhou University Guangzhou, 510006, China)

AbstractIn order to improve the effective drive of double-feet piezoelectric linear actuator and enhance magnifying ability of micro-displacement structure of secondary lever and flexure hinge in actuator, structural parameters of the actuator are optimized. Firstly, the amplification of secondary lever micro- displacement mechanism is calculated theoretically, and the simulation process of the actuator stator is completed based on ANSYS. Secondly, through the simulation analysis, it is found that the comprehensive use of straight circular flexure hinge and straight beam flexure hinge in the actuator stator can optimize the magnification of the actuator stator, and the corresponding magnification of the optimal hinge parameter is 8.131. Thirdly, the prototype of the actuator is made and the amplitude of the stator driving foot is tested, and vibrations of two driving feet are relatively stable. The experimental results show that the displacement amplitude of driving foot I and II floats in the range of 60 and 63 μm. Compared with the existing piezoelectric linear actuator, the actuator has advantages of simple structure, easy installation and debugging, and high stable operation.

Keywordsnon-resonant; double-feet piezoelectric linear actuator; piezoelectric stack; secondary lever; flexure hinge

FluctuationDetectionandFaultDiagnosisofRotatingMachinery

TANYuan1,SUNWenlei1,WENGuangrui1,2,HUANGXin2
(1. School of Mechanical Engineering, Xinjiang University Urumqi, 830047, China)(2.School of Mechanical Engineering, Xi′an Jiaotong University Xi′an, 710049, China)

AbstractThe rotation speed of a rotating machine frequently fluctuates when approaching the machine′s working speed. Current non-stationary signal processing methods hardly detect the rotation speed fluctuations. To tackle the shortage of existing instantaneous frequency evaluation methods, this paper adopts a fast path optimization algorithm for instantaneous frequencies of for non-stationary signals, which is verified with simulation signals and actually measured signals. On this basis the short-time order tracking principle of the parameterized time-frequency analysis theory is elaborated in this paper. Based on the instantaneous frequency variation function of the estimated vibration signals, this method can construct corresponding rotation operators to rotate the time-frequency characteristics of the rotation speed fluctuation signals. Moreover, it can obtain the short-time order tracking spectrum of each time-frequency window which reserves all instantaneous information of the rotation speed fluctuation signals. Experiment results show that this method can accurately extract the characteristics of typical failures of rotating machines under the working conditions of fluctuating rotation speeds, providing a decent precision and reliability.

Keywordsrotating machinery; fault diagnosis; parameterized time-frequency analysis; rotational speed fluctuations

ExperimentalonImpactPowerlessofHeavyHydraulicRockDrillwithDoubleDamperSystem

GENGXiaoguang,MAFei,MAWei,ZHOUZhihong,LIUYuchao
(School of Mechanical Engineering, University of Science and Technology Beijing Beijing, 100083, China)

AbstractComprehensive performance tests are conducted on a certain domestic heavy hydraulic rock drill with double damper system in order to find the reasons of powerless impact and airframe fever reasons. First, the impact energy is measured by the stress wave test, and the pressures of each chamber is monitored, including the piston′s front-chamber and rear-chamber, shuttle valve′s left-chamber and right-chamber, damper system′s first-stage and second-stage chambers. Then, the impact piston′s moving law is derived according to the data, and the damper system′s working condition and damping piston′s equilibrium position are calculated based on the law. The results indicate that the shuttle valve work properly, the damping piston′s equilibrium position is reasonable, and the prototype′s impact powerless and airframe fever are caused by the lag hit. Finally, an improved method to shorten the bushing length is proposed to improve the rock drill′s property by eliminating the impact powerless and alleviating the airframe fever. The comprehensive performance test provides an effective means for rock drills′ troubleshooting.

Keywordsheavy hydraulic rock drill; double damper system; impact powerless; stress wave test; comprehensive performance test

FeatureExtractionMethodBasedonMEDandEnvelopeCepstrum

SUNWei,LIXinmin,JINXiaoqiang,HUANGJianping,ZHANGXianhui
(Science and Technology on Rotorcraft Aeromechanics Laboratory, China Helicopter Research and Development Institute Jingdezhen, 333001, China)

AbstractIn the light of the difficulty for the cepstrum method to draw early weak fault, a new feature extraction method based on minimum entropy deconvolution (MED) and envelope cepstrum is proposed. First, the fault signal is de-noised and the meantime periodic impact components are enhanced by MED method to get the envelope signal. Then, the envelope cepstrum is presented by the cepstrum analysis of the envelope signal. Finally, the fault features are extracted through the envelope cepstrum. The results of the experiments show that the proposed method extract the feature frequency information of incipient fault with higher efficiency than the traditional methods do and can be used to prevent major faults from occurring．

Keywordsrolling bearing; fault diagnosis; cepstrum; minimum entropy deconvolution; envelope signal

EffectsofWheelPolygonalizationonAxleBoxforHighSpeedTrain

ZHANGFubing1,WUPingbo1,WUXingwen1,HEXiaolong1,ZHANGMin2
(1.State Key Laboratory of Traction Power, Southwest Jiaotong University Chengdu, 610031, China)(2.China Railway Rolling Stock Corporation Qingdao Sifang Co., Ltd. Technology Center Qingdao, 266111, China)

AbstractIn the light of the damage of axle box end cover on high speed train, First, the finite element model of the end cover is established for the modal analysis, where the intrinsic mode is captured at frequency around 580 Hz. The results are verified by the later modal test and the comparisons with the field test data show that the intrinsic mode is quite close to the excitation frequency of 20-order wheel polygonalization. In response to this phenomenon, the vehicle multi-body dynamics model containing the axle box end cover is established by multi-body dynamics simulation software, and the vibration characteristic of the bolt and axle box end cover is analyzed. The simulation results show that the acceleration amplitude of axle box end cover is much larger than that of the axle box body. Furthermore, considering the spectrum analysis, the resonance of the end cover can cause the bolts to loosen, which probably happens when the preload drops to 2.5 kN. The above conclusion is consistent with the test results, and another rule is found through the instrumented bolt: as the bolt preload decreases, the acceleration of end cover increases. This paper shows the reason of end cover destroy, and it is of great significance for the running safety of the high speed train.

Keywordsvehicle system dynamics; modal analysis; axle box end cover; wheel polygonalization; multi-body dynamics simulation

MeasuringMethodforWallPressureofCabinwithInnerExplosion

ZHAIHongbo,SUJianjun,LIZhirong,YUANJianfei,WANGShengqiang
(Seventh Research Department, Xi′an Modern Chemistry Research Institute Xi′an, 710065, China)

AbstractA measuring method for wall pressure of cabin with inner explosion is proposed in this paper. First of all, the pressure measuring environment of cabin with inner explosion is analyzed. When explosives explode inside the cabin, the long-lasting thermal shock and the large vibration acceleration of the bulkhead are generated. These will affect the wall pressure testing device and reduce measurement accuracy of the impulse of the bulkhead. Second, a heat-protection installation with heat-protection lipid is adopted to restrain the interference of thermal impact on the pressure sensor. It can withstand the thermal shock in the post-combustion stage and obtain the complete shock wave pressure change curve. Third, in order to suppress the vibration propagation from the wall to the pressure sensor, a vibration isolation mounting structure is designed, which is composed of a sensor, a mounting seat, a spacer ring, a base, and a pressure screw. At last, this paper study the effectiveness of the pressure measuring method via the theoretic analysis and the contrast experiment. The results show that the manner could effectively reduce the thermal shock effect in the duration of 500ms, suppress the influence of bulkhead vibration on the performance of the sensor, and improve the accuracy of wall pressure measuring of cabin with inner explosion. Therefore, the method presented in this paper is feasible for wall pressure measuring of the cabin with inner explosion.

Keywordscabin; inner explosion; thermal impact; vibration; pressure measuring