第39卷第5期英文摘要

PSTTiAlSingleCrystalandItsApplicationProspect

CHENGuang1,2,CHENFengrui1,2,QIZhixiang1,2,FENGChenming1,2,CAOYuede1,2,XUHao1,2,ZHENGGong1,2,
(1. MIIT Key Laboratory of Advanced Metallic and Intermetallic Materials Technology, Nanjing University of Science and Technology Nanjing, 210094, China)(2. Engineering Research Center of Materials Behavior and Design, Ministry of Education, Nanjing University of Science and Technology Nanjing, 210094, China)

AbstractThis paper briefly reviews the research history of TiAl intermetallic compounds. Based on reviewing the research of TiAl single crystals, we focus on the breakthrough in theory, preparation technology and mechanical properties of the new generation of high-performance high-temperature polysynthetically twinned (PST) TiAl single crystals. We further analyze main research of PST TiAl that needs to be carried out in the future. Finally, we prospect the application of this novel PST TiAl single crystals in aero-engine blades.

KeywordsTiAl intermetallic compound; polysynthetically twinned TiAl single crystal; mechanical property; aero-engine blade

CalculationandDesignMethodforSlottedBellevilleSpringofUltrasonicMotor

LENGWeijie,SUNZhijun,PENGHanmin

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

AbstractA calculation model for slotted belleville spring based on the conical shell theory is presented to solve the problem of preloading in the small series of ultrsonic motors. Based on the conical shell theory, the mechanical model for slotted belleville spring is established under the condition of axisymmetric loading and sliding support. The calculation method for the model is studied based on the theory of modern computing methods. A comparative analysis test is made between the experimental data and the results of various computing theories. The results show the model based on the conical shell theory has a higher precision than other methods and the relative error is within ±3.5%. Based on the results of parameter-sensitivity analysis testing for slotted belleville spring, the optimal height-thickness ratio is obtained with the range of 1.5 to 1.8 and the design solution for slotted belleville spring is presented.

Keywordsultrasonic motor; preloading; quasi-zero stiffness; slotted belleville spring; parameter sensitivity

TangentialDynamicBehaviorIdentificationofBoltJoints

ZHENGHualin1，XULin1，HUTeng1，WANGHui2
(1. School of Mechatronic Engineering, Southwest Petroleum University Chengdu, 610500, China)(2. Sichuan Pushningjiang Machine Tool Co., Ltd. Dujiangyan, 611830, China)

AbstractIdentification of joints dynamic behaviors has become a universal issue, which is critical for accurate modeling of mechanical system. In this paper, a thorough methodology is presented to investigate bolt joint tangential dynamic characteristics. Substructure synthesis, based on structure frequency respond functions(FRFs), is employed as the theory mainline to construct the fundamental equation for identifying bolt joint tangential dynamic behaviors. Tangential dynamic stiffness of bolt joint,Za, is deduced afterwards. By virtue of singular value decomposition and least squares approaches, equivalent tangential stiffness parameters,ka, and damping parameter,ca, utilized for bolt joint tangential dynamic modeling in the following step, are identified. Validity of the proposed tangential dynamic model is demonstrated by comparing FRFs obtained numerically and experimentally. Comparison results indicate that frequencies errors of first three characteristic peaks are 1.38%, 1.51% and 0.84%, respectively. It is sufficient to prove that the proposed methodology is efficient for identifying bolt joint tangential dynamic behaviors and the resulting equivalent dynamic parameters are highly accurate so that they can be regarded as theory and data supports for accurate modeling of mechanical system.

Keywordsbolt joint; tangential; dynamic behavior; substructure synthesis

ExperimentalStudyonCharacteristicsofAerodynamicForceonYawedSquareCylinder

DENGRanran1,MAWenyong1, 2,CHAIXiaobing1,ZHENGXi1
(1. College of Civil Engineering, Shijiazhuang Tiedao University Shijiazhuang, 050043, China)(2. Innovation Center for Wind Engineering and Wind Energy Technology of Hebei Province Shijiazhuang, 050043, China)

AbstractSlender structures with square cross-section, which are widely used in civil engineering, expose in the oblique wind during its service. The wind loads on this structure can be simplified as the aerodynamic forces on a yawed square cylinder. Unlike cylinders under wind normal to its length, an estimation of aerodynamic forces for yawed square cylinders are still unclear. In the present study, the wind pressure distribution on the yawed cylinder is tested in the wind tunnel to illustrate the effects of the skew angels on aerodynamic characteristics. The results show that the conventional wind velocity decomposition can only estimate the pressure distribution before the separation points rather than estimate the whole aerodynamic forces on the yawed cylinders. The mean value and standard deviation of aerodynamic forces on the yawed cylinder are smaller than those on the normal cylinders due to the weak wind pressure on the leeward side. The yawed cylinders also have smaller vortex shedding frequency, weaker vortex and wider frequency band than the normal cylinders. Therefore, it is conservative wind load, which uses mean aerodynamic forces for the normal cylinder instead of the yawed cylinder, but the change of the vortex shedding frequency and band of frequency may induce the significant difference on wind-induced vibrations.

Keywordsyawed square cylinder; skewed wind; wind tunnel tests; aerodynamic force; vortex shedding frequency

PredictionofVibrationTrendofSluiceStructurewithAVMD-KELM

ZHANGJianwei1,2,3，HUAWeiwei1,2,3，HOUGe1,2,3，ZHAOYu1,GUOXifang4
(1. School of Water Conservancy, North China University of Water Resources and Electric Power Zhengzhou, 450046, China)(2. Collaborative Innovation Center of Water Resources Efficiency and Protection Engineering Zhengzhou, 450046, China)

(3. Henan Provincial Hydraulic Structure Safety Engineering Research Center Zhengzhou, 450046, China)

(4. Henan Zhongyuan the Yellow River Engineering Company Limited Xinxiang, 453000, China)

AbstractAn adaptive variational modal decomposition(AVMD) combined with kernel extreme learning machine(KELM) is used to predict the vibration of the sluice in the discharge process, which is used to assist decision-making and early warning. Firstly, the decomposition modal number of AVMD is determined based on mutual information criterion to overcome the disadvantage of blindly selecting decomposition parameters of variatronal modal decomposition (VMD). AVMD is used to decompose on-line monitoring vibration sequence of sluice into several IMFs, which is used as input and output of KELM model.Secondly, each component is predicted separately by KELM, the hidden layer does not need to be artificially set and the output weights are calculated using the least squares method. Finally, the prediction results of IMFs corresponding to each measurement point are reconstructed as the final predicted value. Combined with the on-line monitoring data of Yucao Sluice under the condition of free discharge, the AVMD-KELM and KELM models and SVM models are used to predict the vibration trend, and the forecast results are compared and analyzed. The results show that the predicted results of AVMD-KELM modal are closer to the measured values, the calculation speed is faster, the accuracy is higher, and the error is smaller. The method can effectively predict the vibration trend of sluice structure.

Keywordsadaptive variational modal decomposition; kernel extreme learning machine; sluice; vibration prediction

ContactCharacteristicsofJointSurfacesConsideringBulkSubstrateDeformationinMixedLubrication

LILing,YUNQiangqiang,LIZhiqiang,CAIAnjiang,DUANZhishan
(School of Mechanical and Electrical Engineering, Xi′an University of Architecture and Technology Xi′an, 710055,China)

AbstractIn order to investigate the effect of bulk substrate deformation on the micro contact characteristics of joint surfaces in mixed lubrication, a contact stiffness model of joint surfaces considering bulk substrate deformation is proposed. Firstly, the asperity contact stiffness and bulk substrate contact stiffness are obtained by the single asperity-bulk substrate system model, and the contact deformation of asperity is determined by the fixed point iteration method. Then, the normal contact stiffness model of the solid surface is established based on fractal theory with considering bulk substrate deformation. Furthermore, the solid contact stiffness is used to obtain liquid contact stiffness model. The results show that the normal load from the proposed model is smaller than the model that ignores bulk substrate deformation, when the real contact area is constant. Meanwhile, the contact stiffness of joint surfaces is mainly dominated by liquid contact stiffness in the early stage of contact. However, the ratio of the liquid contact stiffness to the total stiffness decreases with increasing the real contact area. Finally, the solid contact stiffness dominates joint surfaces. This model provides a theoretical basis for studying the contact characteristics of joint surfaces in mixed lubrication.

Keywordsjoint surfaces; mixed lubrication; fractal theory; asperities; bulk substrate

QuantitativeEvaluationIndexExtractionofTtransmissionGearRattlePerformance

JIANGYanjun1，DENGZhaoxiang1，GONGWeilun2，KEJun2
(1. The State Key Laboratory of Mechanical Transmission, Chongqing University Chongqing, 400030, China)(2. Chongqing Tsingshan Industrial Co., Ltd. Chongqing, 402761, China)

AbstractBased on the rattle characteristic of gear pair and transmission assembly, a study on establishing quantitative evaluation indexes of rattle characteristic for transmissions is conducted. The test is conducted in a semi-anechoic laboratory. The experimental device is mainly used to test the vibration and noise of the transmission. The drive motor is a high dynamic permanent magnet motor with special torque-rotation characteristics, which can be used to simulate the gas pressure of internal combustion engine and reciprocating inertial force of piston, in order to realize the output torque characteristics of the engine. The rattle characteristic curves of gear pair and transmission assembly are obtained by calculating the standard deviation of velocity difference and energy superposition processing to transmission case vibration data, respectively. The evaluation index vectors of the rattle characteristic are built up by extracting the characteristic parameters from two characteristic curves. They are used for rattle problem analysis of a five speed transmission, and for comparative evaluation to the rattle performance of the transmission before and after optimization. The evaluation results show a good agreement with the subjective evaluation.

Keywordstransmission; rattle; vibration and noise; evaluation index

LoadTestandAnalysisofElectricWheeledLivestockandPoultryInspectionCar

ZHANGTiemin1,2,ZHANGHengchao1,GHENHui1,LIANGLi1
(1. College of Engineering, South China Agricultural University Guangzhou, 510642, China)(2. The National Engineering Research Center for Breeding Swine Industry Guangzhou, 510642，China )

AbstractThe embedded drive control system of the hub motor constitutes of two closed-loop of current and speed controllers. The motor drive circuit, the speed detection circuit, the current detection circuit, and the overcurrent overload protection circuit are designed. The fuzzy adaptive proportion integration differentiation (PID) control algorithm is used to simulate the electric wheel type trolley on the dynamometer platform. The test results show that the trolley is stable and can be operated at different speeds under different load conditions. The protection system is triggered in the case of overcurrent or overload, which prevents the current from being burned out and burns the hardware circuit. The driving control system is safe, reliable and stable, which can provide reference for the analysis and verification of the stability of the electric wheel drive control system.

Keywordsdrive control; double closed-loop; fuzzy adaptive proportion integration differentiation; stability analysis

RollingBearingFaultDiagnosisBasedonSPSOOptimizationMultipleKernel-TWSVM

XUGuanji，ZENGKe，BOLin
(State Key Laboratory of Mechanical Transmission，Chongqing University Chongqing, 400044, China)

AbstractThe kernel selection of twin support vector machine (TWSVM) has an important influence on its classification performance. The kernel of TWSVM is generally local or global one，and the generalization ability and classification performance of the two kernels cannot be achieved simultaneously. Gauss kernel and polynomial kernel are combined in TWSVM to improve its generalization ability and classification performance, and simple particle swarm optimization (SPSO) is used to optimize the weights and parameters. Therefore, a classification model based on SPSO optimization multiple Kernel-TWSVM is proposed, and it is applied to the pattern recognition of rolling bearing fault diagnosis. The experimental results show that multiple Kernel TWSVM has a higher classification accuracy than the single kernel TWSVM and back propagation (BP) neural network.

Keywordsrolling bearings; fault diagnosis; phase space reconstruction; simple particle swarm optimization; multiple kernel twin support vector machine

EffectofHelicalSlotsParametersonVibrationComponentsofLongitudinal-TorsionalHorn

ZHAOBo,YINSen,WANGXiaobo,ZHAOChongyang
(School of Mechanical and Power Engineering, Henan Polytechnic University Jiaozuo, 454000, China)

AbstractIn order to promote technology of longitudinal-torsional composite ultrasonic vibration processing technology, a longitudinal-torsional composite ultrasonic horn structure is designed to better play its advantages of the hard-brittle materials processing. The mechanism of the vibration transformation of the helical slots is deduced, and the influence of the longitudinal and torsional vibration components on the vibration trajectory of the horn is revealed. A finite element analysis is used to define the torsional and longitudinal component ratioj, analyzing the influence of the parameters such as helical slots numbern, helical slots angleθand slot widthdon the torsional and longitudinal component ratioj.jincreases with the addition of the number of helical slotsnand slots widthd, andjincreases first and then decreases with the increase of the helical slots angleθ. The primary and secondary influences of helical slots parameters on ratiojare obtained by the difference analysis method of orthogonal parameters. A new method of torsional vibration measurement is developed, and the results of the finite element analysis are verified by experiments.

Keywordslongitudinal-torsional composite ultrasonic vibration; helical slots; torsional and longitudinal component ratioj; torsional vibration evaluation

DesignofAuxiliaryPowerforMacro-microUltrasonicMotor

LONGTaoyuan,ZHANGTiemin,DONGYikui
(College of Engineering, South China Agricultural University Guangzhou, 510642, China)

AbstractThe internal circuits of macro-micro ultrasonic motor (MMUSM) drive system require multiple independent different amplitudes, high stability and precise power supply. A multiple independent output power with logical link control (LLC) converter and switch integrated voltage regulator is designed. The LLC converter is used to convert alternating current (220 V) to multiple output. The main power is closed-loop controlled to achieve a high-precision regulated output. The other auxiliary output is regulated by a high efficiency MP1584 Buck-regulator. Its drive control system includes a power supply, MMUSM, a macro-micro driver, a grating ruler and a laser scanning vibrometer. The experimental results show that this power supply solves the cross regulation problem existing in the traditional single-stage multi-output power supply. It can provide a stable voltage within ±1%, and the efficiency is ≥80%.It also has a simple circuitand a small size, which is easy to implement in engineering design. In addition, the reliability, the volume and the efficiency of this MMUSM drive system are optimized.

Keywordsmacro-micro ultrasonic motor (MMUSM); LLC converter; multiple independent output; second voltage regulator

DesignofPiezoelectricTunableLinerandControlSystem

LÜHaifeng1,ANJun1,PANHongxia1，LIUJiquan1,2
(1. School of Mechanical Engineering, North University of China Taiyuan, 030051，China)(2. Taiyuan Research Institute Company Limited, China Coal Technology and Engineering Group Taiyuan,030000, China)

AbstractA tunable liner (TL) based on the inverse piezoelectric effect is developed to tackle the shortage of traditional liners, such as unchangeable structure and uncontrollable sensitive frequency. It consists of a neck, resonant chamber and piezoelectric patch which forms a Helmholtz resonator. The finite element modeling (FEM) is used to calculate the resonant frequency and sound pressure distribution of the acoustic system. The transmission loss measurement is carried out in an impedance tube to demonstrate the broadband noise control effect of the linear system. The result indicates that the TL peak frequency remains linear to the drive voltage and the sensitivity is measured to be 0.1 Hz/V. A DC amplifier circuit using photoresistor is designed to construct the function of control voltage, driving voltage, and noise frequency. The control algorithm is developed by LabVIEW software. When the noise frequency drifts from 746 Hz to 788 Hz, the driving voltage can be modulated automatically from 110 to 420 V, and the liner keeps resonating. The adaptive noise control is realized to reduce broadband noise.

Keywordsliner; Helmholtz resonator; frequency; transmission loss

SensitivityAnalysisBasedonLatinHypercubeSamplingMethodandFrequencyEstimationofCoolingTower

KEShitang1,XULu1,2
(1. Department of Civil Engineering, Nanjing University of Aeronautics and Astronautics Nanjing, 210016, China)(2. Group Guangdong Electric Power Design Institute Co., Ltd. China Energy Engineering Guangzhou, 510700, China)

AbstractIt is of great significance to reveal the sensitivity of structural parameters to the natural frequencies of large cooling towers, such as the wind resistance, seismic design and dynamic characteristics optimization design of cooling towers. The natural frequencies of the existing cooling towers are mainly obtained by finite element analysis, and there is no simple and effective formula for estimating the natural frequencies of the cooling towers. In order to resolve this problem, taking a large cooling tower as the reference tower, firstly, 38 models of the reference tower are obtained by changing the typical parameters of the structure, and the dynamic characteristics are analyzed. The law of fundamental frequency and overturning frequency changing with the structure parameters is extracted. Then, the sensitivity of the structural natural frequency parameters is analyzed by perturbation and Latin hypercube sampling method, and the sensitive factors of various structural parameters under different orders are obtained. On this basis, the practical estimation formula of multi-parameter fundamental frequency and overturning frequency considering sensitivity factor weight is innovatively fitted. Finally, in order to verify the accuracy of the formula for the estimation of the natural frequencies, the error analysis of the cooling towers selected by the research group is carried out.

Keywordscooling tower; finite element analysis; sensitivity analysis; frequency of vibration; estimation formula

ResearchonSemi-flexibleValvePiezoelectricPump

FUJun1,2,ZHANGJianhui1,3,WANGYing4,YANQiufeng1
(1. State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of
Aeronautics and Astronautics Nanjing, 210016, China)(2. No.650 Institute, Hongdu Aviation Industry Group, Aviation Industry Corporation of China Nanchang, 330024,China)

(3. College of Mechanical and Electrical Engineering，Guangzhou University Guangzhou, 510006,China )

(4. College of Mechanical and Electrical Technology, Taizhou Polytechnic Institute Taizhou, 225300,China)

AbstractIn this paper, a kind of semi-flexible valve piezoelectric pump is designed according to the structure of venous valves. The change between the valve and valveless state of the piezoelectric pump can be achieved, because the driving end of the piezoelectric oscillator is controllable. Firstly, the structure and the working principle of the piezoelectric pump with half flexible valve are introduced. Then the valve body is analyzed theoretically, and finally the experimental prototype is fabricated and tested. The experimental results show that when the drive voltage is 220 V and the frequency is 7 Hz, the inlet and outlet pressure difference of the half flexible valve piezoelectric pump can reach 199 mm. When the drive voltage is 220 V and the frequency is 11 Hz, the experimental flow of the half flexible valve piezoelectric pump is 44.5 ml/min. With the increase of the driving voltage, there is a single peak and double peak in working frequency and flow rate results, respectively. The research proves that the half flexible valve piezoelectric pump has the function of pump and can realize the conversion of valve and valveless state, verifying its validity and theoretical analysis correctness.

Keywordspiezoelectric pump; venous valve; semi-flexible valve piezoelectric; piezoelectric vibrator

TimeAveragedPressureDistributionandAerodynamicForceofFlowAroundThreeCircularCylindersinTandemArrangement

YANGQun1，2，LIUQingkuan2，3，LIUXiaobing2，3
(1. School of Civil Engineering，Shijiazhuang Tiedao University Shijiazhuang, 050043, China)(2. Innovation Center for Wind Engineering and Wind Energy Technology of Hebei Province Shijiazhuang，050043，China)

(3. Wind Engineering Research Center，Shijiazhuang Tiedao University Shijiazhuang, 050043, China)

AbstractIn order to provide a reference for wind load value of circular cylinder structures in tandem arrangement, time averaged pressure distribution and aerodynamic force of flow around single circular cylinder, two and three circular cylinders in tandem arrangement under different spacing are investigated through pressure-measured rigid model wind tunnel tests. The spacing ratioL/Dfor two and three circular cylinders in tandem arrangement ranges from 1.2 to 12.0, whereDis the diameter of single circular cylinder andLis the distance between the centers of two circular cylinders. The Reynolds number is 3.4×104. Aerodynamic interference effects on time averaged pressure distribution and drag force of three circular cylinders are discussed by comparing to those of single circular cylinder. The variation of interference effect with number of cylinders was studied by comparing with those of two circular cylinders. The research results show that there are two different flow fields for three circular cylinders in tandem arrangement. The critical spacing ratio, (L/D)cris between 3.5 and 4.0. There exists significant differences between time averaged pressure distribution and drag force under two flow fields.

Keywordsthree circular cylinders in tandem arrangement; flow; time averaged pressure distribution; time averaged drag force; wind tunnel test

GearboxFaultDiagnosisBasedonAdaptiveModifiedDual-treeComplexWaveletTransform

CHENXuyang1,HANZhennan1,NINGShaohui2
(1. School of Mechanical Engineering, Taiyuan University of Technology Taiyuan,030024, China)(2. School of Mechanical Engineering, Taiyuan University of Science and Technology Taiyuan,030024, China)

AbstractIn the light of frequency aliasing and parameter custom caused by doubletree complex wavelet transform, a fault diagnosis method of adaptive improved dual-tree complex wavelet transform is proposed. This method integrates dual-tree complex wavelet transform-variational mode decomposition (DTCWT-VMD). First, the signal is decomposed and reconstructed by dual-tree complex wavelet transform. Particle swarm optimization (PSO) is used to determine the component kurtosis value as a fitness function to select the optimal decomposition level of doubletree complex wavelet. Second, the reconstructed low-frequency signal is subjected to spectrum analysis to extract the fault characteristic signal. The high-frequency components are reconstructed by variational mode decomposition, and through the kurtosis value, the main frequency component signal of each high-frequency component decomposed by variational mode is obtained. Finally, the spectrum of the main frequency component signals is analyzed to identify the fault frequency of the gearbox. The experimental results show that the proposed method eliminates frequency aliasing and improves the correctness of signal-to-noise ratio and frequency band selection compared with that process by the dual-tree complex wavelet transform and variational mode decomposition. Besides, it improves the ability to extract transient shock characteristics from a strong noisy environment.

Keywordsdual-tree complex wavelet transform; particle swarm optimization; variational mode decomposition; kurtosis value; gearbox; fault diagnosis

InvestigationonSignalCharacteristicsRecognitionMethodsofRotor-StatorInteractionforCentrifugalCompressor

LIHongkun1,FUJingqiang1,YANGShuhua2,WANGKaiyu2
(1. School of Mechanical Engineering, Dalian University of Technology Dalian, 116024, China)(2. Shenyang Blower Works Group Corporation Shenyang, 110023, China)

AbstractFor a centrifugal compressor, as a result of the relative motion of static and dynamic blade rows, it will cause the rotor-stator interaction induced by the airflow in the compressor, to produce the unsteady airflow exciting force and the high amplitude pressure pulsation. The unsteady rotor-stator interaction has an important influence on the stability, normal operation and practical efficiency of the compressor. In order to effectively study the signal characteristics of rotor-stator interaction, the operational modal simulation calculation for the impeller of a model centrifugal compressor test rig is carried out to obtain the impeller interferogram, and determine the speed conditions at which the inlet guide vanes (IGV) or the outlet guide vanes (OGV) has interference to the impeller. Finally, a strain test and a pressure fluctuation test are carried out under the determined experimental speed conditions. Through the analysis and comparison, the existence of the interference characteristic frequency under the simulated rotating speed conditions is verified, and the strain signal is also proved to be more suitable for identifying the characteristics of the interference signal. Through summing up the relationship between the interference characteristic frequencies of the serious interference speed conditions and the natural frequencies of the impeller, it lays the foundation for further improvement of centrifugal compressor.

Keywordscentrifugal compressor；inlet guide vanes； impeller； outlet guide vanes；rotor-stator interaction

MeasurementandComputationalAnalysisofSoundInsulationPerformanceofaPlatewithDampingTreatment

JIANGHong1,CHENLingqing1,4,XIEXinxing2,HEJianjie2,SHANGGUANWenbin3
(1. School of Mechanical Engineering, Jiangsu University Zhenjiang, 212000, China)(2. Ningbo Tuopu Group Co., Ltd. Ningbo, 315807, China)

(3. School of Mechanical and Automotive Engineering, South China University of Technology Guangzhou, 510641, China)
(4, Technical Center of Dongfeng Commercial Vehicle Co., Ltd. Wuhan, 430156, China)

AbstractThe damping loss factor of a plate with damping treatment is measured by the impulse response method. The influence of the coverage ratio of the damping and the test condition on the damping loss factor of a plate is analyzed. The sound insulation of the plate is tested using anechoic-reverberation chamber, and the test results of the plate with different coverage of the damping material are compared. The calculation model of the sound insulation of the plate is established. The calculated values are in good agreement with the experimental data, which proves the validity of the model. Based on this model, the influence of the thickness and coverage of the damping material on the sound insulation performance of the structure is studied. Considering the characteristics of lightweight and sound insulation, the influence of the thickness and coverage of the damping material on the noise reduction efficiency is analyzed and the noise reduction optimization is carried out with the goal of maximizing the noise reduction efficiency.

Keywordsacoustics; damping loss factor; transmission loss; plate with damping treatment

DynamicsCharacteristicsofaPlowSystemBasedontheQualitySubstitutionMethod

ZHANGYu1，MAOJun2，CHENHongyue2，HAOZhiyong2
(1. School of Mechanical Engineering，Anyang Institute of Technology Anyang, 455000，China)(2.School of Mechanical Engineering，Liaoning Technical University Fuxin, 123000, China)

AbstractIn the light of computation divergence causing by zero quality existing of the finite element dynamic model of a plow system，symbiotic time-varying dynamical equations of longitudinal vibration and contact-impact vibration are established based on the quality substitution method considering the factors of plow head movement, the clearance of plow head and sliding framework, pretension force of plow chain and polygon effect of sprocket. The test uses the planning load of bit as excitation. Time-varying dynamical equations are solved with the numerical analysis method. Dynamic characteristics of plow system under different depths are analyzed，and compared with the calculation results of the dynamic model before improvement and experimental results. The results show that the problem of computation divergence are avoided by using the suggested method, and the computational accuracy of the dynamical model are improved. The research results provide theoretical basis for working stability, fatigue life of key parts analysis of plow system.

Keywordsplow；dynamic characteristics；quality substitution method；finite element

DCCA-NSEn-BasedCouplingNetworkModelingandEvaluationMethodforComplexElectromechanicalSystems

FENGLongfei，GAOJianmin，GAOZhiyong，XIEJuntai，GAOXu
(State Key Laboratory of Manufacturing Systems Engineering, Xi′an Jiaotong University Xi′an, 710049,China)

AbstractConsidering that there are many monitoring points in process industrial production system and aiming at the correlation among monitoring points, a method is proposed to comprehensively evaluate the state of multiple variables in the system, based on detrended cross correlation analysis (DCCA) method and network structure entropy method (DCCA-NSEn). We use the DCCA method to calculate the correlation between the multivariate variables, and construct a weighted network model which reflects the multivariable coupling relationship. Time window sliding in the monitoring sequence to obtain the dynamic evolution model of system′s coupling relationship network. The NSEn method is used to calculate the network structure entropy of the coupled network model in each time period. Finally the state of the complex electromechanical system is evaluated according to the network structure′s entropy changes over time. This paper presents the real production data of a compressor unit to verify the DCCA-NSEn method, then the multivariate analysis of the same group of production data is conducted by the coupling detrended fluctuation analysis (CDFA) method. The results of the two methods are compared. The results show that compared with the DCCA method, this method has the advantages of multivariate simultaneous monitoring and evaluation. Compared with the CDFA method, which is also a multivariate analysis method, the DCCA-NSEn method has the advantages of stable evaluation effect and obvious effect on the abnormal state detection of the system.

Keywordsdetrended cross correlation analysis (DCCA); coupling relation network; net structure entropy (NSEn); state assessment; complex electromechanical systems

ANewMethodofDe-noisingofPendulumSignalandItsApplication

LIUYong1，HEShengguo1，YANGQingyong2，GAOBingchun1，LIUPeng1，LEIYanke1
(1. The College of Information Engineering of Xiangtan University Xiangtan，411105，China)(2. Guangxi Guimao Electric Power Co., Ltd. Hechi, 546300, China)

AbstractThe swing signal of the hydraulic turbine unit includes strong impulse noise and Gauss white noise due to the disturbance of the field environment and equipment. This results in the real effective signal being submerged which brings great difficulty for signal extraction. In the light of this problem，a swing signal denoising method that combines median filtering，wavelet threshold de-noising and Savitzky-Golay smoothing filter is proposed. First，the median filter is used to remove the impulse noise in the analysis signal. Then，the Savitzky-Golay smoothing filter and threshold denoising are used to remove the white noise components in approximate coefficient and detail coefficient after wavelet decomposition respectively. The simulation results show that the method can effectively increase the signal-to-noise ratio(SNR)，local correlation index(LCI) and smoothness(S)，and reduce the mean square error(MSE). The experimental results show that the method can not only remove the noise in the swing signal of the water turbine，but also effectively retain the details of the real signal.

Keywordsthrow signals; wavelet de-noising; median filtering; Savitzky-Golay filtering；approximate coefficient

ACalculationMethodofLambWavesExcitationResponseinaPlate

XUXining1,YUZujun1,2,XINGBo1,ZHULiqiang1,2
(1. School of Mechanical, Electronic, and Control Engineering, Beijing Jiaotong University Beijing, 100044, China)(2. Key Laboratory of Vehicle Advanced Manufacturing, Measuring and Control Technology (Beijing Jiaotong University), Ministry of Education Beijing, 100044, China)

AbstractIn order to analyze Lamb wave propagation characteristics, a response calculation method based on a semi-analytical finite element is used to solve the Lamb wave excitation response in a plate instead of the conventional experimental method. Compared with the three-dimensional finite element simulation method, simulating the propagation process of guided wave in waveguide medium, via measuring the response of stimulation, can improve the computational efficiency. The Lamb wave excitation response is derived from the previous system functional model by solving the general homogeneous equation of the Lamb wave in the thin plate based on the principle of spectral superposition. For both response and experimental data, the wavelet transform is used to calculate Lamb waves' group velocities. Experimental results are in good agreement with the data obtained by excitation response calculation method. In addition to that, the modal analysis shows consistency. Moreover, the excitation response calculation method is a versatile approach, which can also be used to simulate the propagation process of the guided wave in any section waveguide medium.

KeywordsLamb wave; exciting and response; semi-analytical finite element; mode; group velocity

ANovelFaultDiagnosisMethodBasedonSemi-supervisedMax-marginDictionaryLearning

WANGWeigang1,TAOJing1,LIUZhansheng2
(1. College of Mechanical Science and Engineering, Northeast Petroleum University Daqing, 163318, China)(2. School of Energy Science and Engineering, Harbin Institute of Technology Harbin, 150001, China)

AbstractIn the light of marked fault samples and low recognition rate of the traditional semi-supervised diagnosis method，a novel fault diagnosis method, which is based on semi-supervised max-margin dictionary learning (SSMMDL), is put forward. In the proposed method, an unmarked sample reconstruction error term is added to the max-margin dictionary learning model. By minimizing the four terms, including unmarked samples sparse reconstruction error term, marked samples sparse reconstruction error term, the regular items of the loss function in support vector machine (SVM) and the regular items of classification interval regularization, the synchronous learning of the dictionary and the SVM is realized. and the dictionary with the discriminant ability is built. On this basis, the sparse representation of test samples is obtained. At last, we identify the faults by the classifier based on sparse representation. The different faults of rotor are recognized. The experimental results show that the proposed method is more accurate than the comparative algorithms in terms of accuracy rate, and succeeds in meeting the needs of online monitoring of mechanical fault diagnosis.

Keywordsfault diagnosis; support vector machine; sparse coding; semi-supervised max-margin dictionary learning

StabilityAnalysisofContinuous-TimeHigherHarmonicControlforActiveRotor

ZHOUJinlong,DONGLinghua,YANGWeidong
(National Key Laboratory of Rotorcraft Aeromechanics, College of Aerospace Engineering, Nanjing University of Aeronautics and Astronautics Nanjing, 210016, China)

AbstractActive rotor with trailing-edge flaps is an effective methodology for helicopter rotor vibration control. Continuous-time higher harmonic control (CTHHC) algorithm is widely used both in simulation and experiment to alleviate rotor vibratory loads. The vibration control performance and stability of the active rotor system are mainly dependent on the parameters of CTHHC controller. A parametric model of active rotor for active vibration control, including the plant model in the form of transfer function which is obtained based on data of hover test, is established, and the simulation is conducted using this model. Nichols chart is employed to analyze the stability and stability margin of the active rotor system. The time constant and phase characteristics of the system are tuned to extend the stability margin of the system without remarkable attenuation of the vibration control performance. The effect of parameter adjustment on system performance and stability is studied through this simulation analysis, and it will be instructive for tuning controller parameters in active rotor experiments.

Keywordshelicopter; rotor; vibration control; continuous-time higher harmonic control; stability

FaultDiagnosisofBearingBasedonCSR-ISOMAP

SHIYing,ZHUANGZhe,LINJianhui
(State Key Laboratory of Traction Power, Southwest Jiaotong University Chengdu, 610031, China)

AbstractThe performance of convolution sparse representation (CSR) in extracting impulses is sensitive to its improper penalty parameters. A novel fault detection method which is based on the combination of CSR, Hilbert transform (HT) and manifold learning is proposed. The impulses with different sparse characteristics are extracted by CSR at different penalty parameters. The impulse-envelope space is constructed with the Hilbert transform on the extracted impulses. The manifold based on Isomap is executed to learn the low-dimensionality intrinsic envelope of vibration signals for fault detection. The capability of the proposed fault detection method is verified by fault simulations as well as controlled experimental tests. The results show that the proposed fault detection method based on CSR-HT-Isomap can extract the fault characteristics of the inner and rolling fault. The method is also compared with two other envelope spaces spanned by the Hilbert transform on ensemble empirical mode decomposition and wavelet packet transform, respectively. The comparison shows that the CSR-Hilbert Transform-Isomap method is superior in extracting the intrinsic envelope, strengthening the amplitude of intrinsic envelope spectra and enlarging the harmonic number of fault-characteristic frequency.

Keywordsaxlebox bearing; convolution sparse representation; Hilbert transform; isometric feature mapping (ISOMAP); fault diagnosis

DesignOptimizationofThreeDegreesofFreedomUltrasonicMotorStatorBasedonResponseSurfaceModel

NIUZijie1,SUNZhijun2,CUIYongjie1
(1. College of Mechanical and Electronic Engineering, Northwest Agriculture and Forestry University Xi′an, 712100, China)(2. State Key Laboratory of Mechanics and Control of Mechanical Structures, Nanjing University of Aeronautics and Astronautics Nanjing, 210016, China)

AbstractThe stator design optimization method based on the response surface model is proposed to solve various problems in the design and optimization of the stator structure of the motor. They include that the stator design mode of the stator is not completely separated from the disturbance mode, the stator vibration amplitude is small and the stator vibration is large in the local internal stress. First, the sample point is selected in the design space for the Latin hypercube sampling method when setting the stator design size as a variable. The stator modal and harmonious response value is obtained by the finite element analysis of the stator size structure obtained by the combination of each sample point, and the stator response surface model is established. Then, the remains are used. The transmission algorithm optimizes the stator on the basis of the response surface model. Finally, the finite element software is used to model the stator before and after the optimization to verify the correctness of the optimization results.

Keywordsresponse surface methodology (RSM); genetic algorithm; Latin-Hypercube sampling; structural optimization

CalculationandAnalysisofWaveformDistortionCoefficientofPilebyCross-HoleSonicLogging

WEIKuiye1,2,ZHANGHongbing1,SONGXinjiang2,ZHUShibin2
(1. School of Earth Science and Engineering,Hohai University Nanjing, 211100, China)(2. Anhui and Huaihe River Water Resources Institude Bengbu, 233000, China)

AbstractCross-hole sonic logging has been widely used in the detection of the integrity of bored pile, which use the acoustic parameters(velocity, wave amplitude, product of the slope of two adjacent lines on the time-depth curve and acoustic time difference(PSD) and the extent of waveform distortion to determine the classification of pile integrity, but the extent of waveform distortion can not be expressed quantitatively. The waveform distortion coefficient and the critical value of distortion coefficient is calculated by the point energy statistics method in frequency domain, using the spectrum analysis and wavelet packet analysis method to explore the features of normal waveform and distortion waveform (the measuring point of pile with bottom sediment, low intensity and non dense pile, broken pile), and the feature vector is structured via the frequency band energy of 3 layer wavelet packet decomposition signal. The results show that the spectrum function for the measuring point on the pile with bottom sediment is stepped, the spectrum energy for the measuring point on broken pile is mainly distributed in the low frequency part; and the eigenvector of the normal measuring points is the largest; the broken pile is the smallest; the non-dense measuring points with low intensity have 1 upper convex point.

Keywordscross-hole sonic logging; wavelet packet analysis; eigenvector; coefficient of waveform distortion; point energy statistics method in frequency domain

MultipleSignalDecompositionMethodforMulti-stepForecastingofTyphoonWindSpeed

LIChunxiang,LIZhou
(Department of Civil Engineering, Shanghai University Shanghai, 200444, China)

AbstractLong-span bridges and high-rise buildings are widely distributed in southeastern coastal areas of China. However, this area is also affected by typhoons every year. Accurate prediction of typhoon wind speed is a very important means of increasing disaster prevention capabilities of engineering structures and auxiliary decision-making. In this paper, a comparative study in different signal decomposition methods used in multi-step forecasting of wind speed is carried out. First, the characteristics of eight typical signal decomposition methods are enumerated. Then, the least squares support vector machine (LSSVM) prediction model based on particle swarm optimization (PSO) optimization is established based on different signal decomposition methods. Finally, the multi-step ahead forecasting experiment is carried out using two measured wind speed, which are collected from the main tower of a long-span bridge and the roof of a high-rise building. The prediction results of the two groups of experiments show that the VMD-LSSVM-PSO model has the best prediction performance.

Keywordstyphoon; multi-step wind speed forecasting; time-frequency analysis; signal decomposition; wind disaster auxiliary decision-making

InfluenceofForceLoadonUltrasonicLongitudinal-TorsionalCompositeDrillingSystem

CHANGBaoqi,ZHAOBo,YUANLusheng,LIPengtao,ZHAOChongyang
(School of Mechanical and Power Engineering, Henan Polytechnic University Jiaozuo, 454000, China)

AbstractIn the ultrasonic assisted drilling of titanium alloy machining, to solve the problems of system detuning, amplitude attenuation and even vibration loss after the load is applied to the acoustic system, the theoretical and experimental research on the force load of acoustic system is carried out. The four-terminal network method is used to unify the transducer, the composite horn and the load, and the overall theoretical model of the ultrasonic drilling acoustic system is established. The ANSYS commercial software package is used to simulate the acoustic system with static and dynamic drilling forces. The design covered the mechanical (force-loading) test and actual drilling processing experiment, explored the force load effect on the system characteristics. It is proved that a rise in the force load increases the system input impedance, shifts the resonance frequency, and reduces the system amplification factor. In the ultrasonic drilling of titanium alloy processing, the current is increased by more than 60%, and when the frequency variation/shift exceeds 350Hz, the acoustic system will exhibit significant detuning, which, in turn, will deteriorate the system stability. The research results have certain guidance and reference significance for ultrasonic assisted drilling.

Keywordstheoretical model; longitudinal-torsional composite; force load; amplitude; frequency

SinkingResistanceofJackedPilesinClayeySoilBasedonFBGSensingTechnology

WANGYonghong1, 2,ZHANGMingyi1, 2,BAIXiaoyu1, 2,LIUJunwei1, 2，MIAODezi1
(1. School of Civil Engineering, Qingdao University of Technology Qingdao, 266033, China)(2. Cooperative Innovation Center of Engineering Construction and Safety in Shandong Blue Economic Zone Qingdao, 266033, China)

AbstractIn order to explore the applicability of fiber bragg grating (FBG) sensing technology for testing sinking resistance of jacked pipe piles in clayey soil, jacked model pipe piles are tested in homogeneous clayey soil. Miniature FBG strain sensors with enhanced sensitivity and dual-diaphragm FBG soil pressure sensor are used for data acquisition. Pile tip resistance and pile shaft resistance are analyzed during pile penetration based on FBG sensing technology for strain data acquisition. By changing the pile diameters, pile length, open-ended and close-ended pile, the difference of the penetration process of jacked pipe piles is analyzed for comparison based on FBG sensing technology. The results indicate that the requirement of FBG technology for testing of sinking resistance of jacked pipe piles in clayey soil can be wonderful satisfied. The sinking characteristics of jacked pipe piles is accurately demonstrated. Variation process of pile tip resistance and pile shaft resistance with various pile diameters, pile length, open-ended and close-ended pile are clearly reflected. The conclusion has major reference value for model test of jacked pipe piles and engineering design.

Keywordsfiber Bragg grating sensing technology; clayey soil; mode pipe pile; pile-sinking resistance; calibration