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18 February 2019, Volume 39 Issue 1 Previous Issue    Next Issue

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Vibration Reduction Analysis and Experiment Verification of Spatial Truss Structures 2019, 39(1): 1-4.  DOI: 10.3969/j.issn.1006-1355.2019.01.001 Abstract ( )   PDF (1387KB) ( )   Space truss structure due to the stiffness of the wall, the end load cantilever installation, the traditional method of direct application of constrained damping layer, vibration damping effect is not obvious. This article describes a method of breaking a long tube structure, applying a free damping layer on the connecting tube, and connecting the long tube through an adhesive. This structure has better damping effect and lighter weight than the structure directly applying the constrained damping layer on the long tube. The optimal structure of space trusses and space loads is designed by optimizing and comparing the damping factors. Using the B&K test system, the data acquisition during the vibration test of the original model and the new model of the long tube was performed. Accelerated response of the point of interest of the space truss structure in three directions of X, Y, Z was obtained. The test results show that the method of breaking the long tube design and applying the viscoelastic constrained damping layer is simple and easy to implement, it can effectively reduce the vibration level of the load at the end of the truss, which is of great significance for the vibration damping design of other space structures. Related Articles | Metrics

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Influence of Vibration Characteristics of Elderly-assistant Robots on Hand Comfort inWalking Posture 2019, 39(1): 5-9.  DOI: 10.3969/j.issn.1006-1355.2019.01.002 Abstract ( )   PDF (1557KB) ( )   Due to uneven road or instantaneous impact is encountered in the process of assisting the elderly to walk outdoors using the elderly-assistant robot, it not only gives the robot impact vibration, but also very importantly, it imparts segmental vibration of the elderly’ hands. Impact vibration resistance characteristics of the robot and analysis of walking comfort of the elderly due to impact was carried out in order to research the elderly-assistant robot whether meet the comfort requirement of the elderly or not. First, the forced vibration of the front and rear wheels of the robot under different displacement input was analyzed and the double shaft vertical degree and pitching degree vibration model of the robot was established. Then, the vibration model of the elderly’ hands was established by using the geometrical relationship of the robot. Finally, Matlab/Simulink software was used to simulate the model for impact resistance vibration characteristics of the robot and walking comfort of the elderly from both situations, which are instantaneous impact and uneven road, respectively. The results show that the vibration amplitude of the hands of the elderly and vibration velocity are small under the two situations, thus, the elderly-assistant robot meets the elderly comfort requirement of operation by hands. The research process provides a theoretical basis for analysis of the related issues for the same kind of robot. Related Articles | Metrics

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Application of Improved Fourier Series Method in Vibration Analysis of Beam Structures 2019, 39(1): 10-15.  DOI: 10.3969/j.issn.1006-1355.2019.01.003 Abstract ( )   PDF (1775KB) ( )   The vibration characteristics of Euler-Bernoulli beam under general boundary conditions were studied. Firstly, the displacement function expression of the beam structure is established based on the modified Fourier method. The displacement function is expressed as a superposition of a Fourier cosine series expansion and an auxiliary polynomial function, and then Lagrange is established using the principle of minimum potential energy. The equation is solved by the Rayleigh-Ritz method, and then the characteristic equation of the beam structure is obtained. The natural frequency and mode shape of the beam structure can be obtained by solving it. By discussing the influence of rotation and lateral spring stiffness on the convergence of the calculation results, the numerical stability of the method is verified, and the spring stiffness values used to simulate several classical boundary conditions are obtained. The calculated results are in good agreement with the finite element method, thus verifying the accuracy of the method. On this basis, the response characteristics of the forced vibration of the beam structure under different boundary conditions are compared. Finally, the differences between the effects of the rotation direction and the stiffness of the transverse spring on the vibration characteristics of the beam structure are discussed. Related Articles | Metrics

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Sound Radiation Performance of Stiffened Plates on Elastic Foundation with Elastic Boundary Conditions SHENG Li yonggan --sun 2019, 39(1): 16-23.  DOI: 10.3969/j.issn.1006-1355.2019.01.004 Abstract ( )   PDF (2845KB) ( )   Related Articles | Metrics

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Contribution Analysis of Noise on Driver’s Ear Side of High Speed Vehicles 2019, 39(1): 24-28.  DOI: 10.3969/j.issn.1006-1355.2019.01.005 Abstract ( )   PDF (2164KB) ( )   Related Articles | Metrics

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An Automatic Optimization Method of Pipeline Clamp Positions 2019, 39(1): 29-33.  DOI: 10.3969/j.issn.1006-1355.2019.01.006 Abstract ( )   PDF (1557KB) ( )   Related Articles | Metrics

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Dynamic Simulation Analysis and Test Verification of Truck Fuel Tank based on Fluid-structure Coupling 2019, 39(1): 34-40.  DOI: 10.3969/j.issn.1006-1355.2019.01.007 Abstract ( )   PDF (1996KB) ( )   A light truck in the road test found that the fuel tank tended to cracking of solder joints and shedding of baffle plate, especially the fuel tank containing 50% fuel. For this, a fluid-structure coupling method was adopted, thus modal analysis and random vibration analysis of the fuel tank were carried out based on fluid-structure coupling equation. The result of modal analysis for different liquid-filling ratio of the fuel tank indicated that the modal frequency of fuel-containing tank is lower than the empty fuel tank, and as the increase of oil injection, modal frequency increases mildly with the increase of order. On the basis of the modal analysis, the vibration analysis of the fuel tank containing 50% fuel was conducted, extracting the solder joints’ stress of horizontal, longitudinal, vertical directions and severe direction, it was turned out that the calculation error is within 10% compared with the experimental data, which verified the correctness of the proposed analysis method. Related Articles | Metrics

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Study on Seismic Dynamic Characteristics of Container Cranes based on Shaking Table Tests 2019, 39(1): 41-45.  DOI: 10.3969/j.issn.1006-1355.2019.01.008 Abstract ( )   PDF (1780KB) ( )   Related Articles | Metrics

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Pendulum Support Vibration Analysis of Column Load Sensors 2019, 39(1): 46-51.  DOI: 10.3969/j.issn.1006-1355.2019.01.009 Abstract ( )   PDF (1825KB) ( )   Related Articles | Metrics

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The discomfort model and experimental study of vertical vibration for the micro commercial vehicle 2019, 39(1): 52-55.  DOI: 10.3969/j.issn.1006-1355.2019.01.010 Abstract ( )   PDF (1456KB) ( )   The micro commercial vehicles are very popular in the developing areas of China for its extraordinary loading ability. With the increasing demands of customers for improving the riding comfort of vehicles, it becomes necessary to investigate the discomfort of vibration for the micro commercial vehicles, and establish the predicting model of discomfort, which contributes to better guidance of the vibration control of the vehicles. Considering the complex road conditions in the developing areas, the discomfort produced by vibration of the micro commercial vehicle when it is running in four types of road conditions (i.e., the asphalt, concrete, gravel and bump road) was investigated. Six vibration stimuli with the root mean square (r.m.s.) values of the Wb weighted accelerations ranging from 0.531 to 2.991 m/s2 were applied for each road condition, so there were totally 24 vibration stimuli. Thirty subjects evaluated the discomfort of vibration in absolute magnitude estimation method. The predicting model of the discomfort of vertical vibration was established based on the Stevens’ power law. Related Articles | Metrics

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Process Parameter Adjustment of Engine Valve Springs 2019, 39(1): 56-59.  DOI: 10.3969/j.issn.1006-1355.2019.01.011 Abstract ( )   PDF (1559KB) ( )   Related Articles | Metrics

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Study on Vibration Transmission Characteristics of Double-layer Bottom under Different Excitations 2019, 39(1): 60-66.  DOI: 10.3969/j.issn.1006-1355.2019.01.012 Abstract ( )   PDF (2323KB) ( )   Related Articles | Metrics

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Research on Evaluation of Transmission Gear Rattle based on Psychoacoustics 2019, 39(1): 67-72.  DOI: 10.3969/j.issn.1006-1355.2019.01.013 Abstract ( )   PDF (1573KB) ( )   Transmission gear rattle noise has characteristics of sound pressure level jump and broadband frequency range. Gear rattle noise can causes annoyance to the passengers when transfer to the vehicle cabin ,and then affects the NVH performance of the automobile. However, the traditional A-weighted sound pressure level(SPL) can not reflect the rattle noise characteristics effectively, which means the rattle noise can not be effectively evaluated by just using SPL. Therefore, in order to effectively evaluate the rattle noise, based on the psychoacoustic theory, both the subjective evaluation tests and objective psychoacoustic parameters were conducted of transmission rattle noise，correlation analysis were done between subjective evaluation and objective psychoacoustic metrics. Correlation results shows that correlation coefficient of SIL, loudness, roughness, sharpness with the subjective evaluation are over 0.9. Then, a prediction model for the rattle noise evaluation was established by using MLR(Multiple Linear Regression) .The model was tested and verified. Results shows that the regression coefficient was 0.936, and the prediction error was within 10%. This work provides reference for the evaluation of rattle noise. Related Articles | Metrics

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Application of Operational Transfer Path Analysis in Steering Wheel Vibration Source Identification 2019, 39(1): 73-77.  DOI: 10.3969/j.issn.1006-1355.2019.01.014 Abstract ( )   PDF (1576KB) ( )   Related Articles | Metrics

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Analysis of Testing Method for Dynamic Loads of Propulsion Shafting Systems 2019, 39(1): 78-83.  DOI: 10.3969/j.issn.1006-1355.2019.01.015 Abstract ( )   PDF (1603KB) ( )   The propulsion shafting system of ships bears complicated load and stress while sailing. Well load distribution is of great importance to ship’s long-term and safe voyage. In this paper, a wireless telemetry system based on strain gages was designed to measure the dynamic loads of the propulsion shafting system in different shaft alignment states. On the basis of the strain in different sections measured and one-support calculation model, the real loads of different bearings can be calculated. Experiment was carried out in the scaling model. Gap of results in the experiment and the finite element model was small. Thus reliability of this testing method was verified. Related Articles | Metrics

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Performance Study on Cluster Active Noise Control System in Helicopter Cabins 2019, 39(1): 84-88.  DOI: 10.3969/j.issn.1006-1355.2019.01.016 Abstract ( )   PDF (1585KB) ( )   The cluster control system which is made up of multiple small scale multichannel centralized system could balance the complexity and risk of instability between centralized and decentralized system. The theoretical analysis for active control of tonal noise in enclosure are carried out and the steady state error and the stable condition have been obtained. Finally, experiments on active tonal noise control in a mock-up of helicopter cabin are investigated, and it is shown that both equivalent noise reduction compare with centralized system and better stability compare with decentralized system has been achieved. Related Articles | Metrics

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Cabin Noise Prediction and Control in Cruise Ships Based on SEA 2019, 39(1): 89-93.  DOI: 10.3969/j.issn.1006-1355.2019.01.017 Abstract ( )   PDF (1682KB) ( )   Based on the Statistical Energy Analysis, cabin noise is predicted and controlled in cruise. The main noise sources of cruise ship are analyzed, including air and structural noise generated by power equipment such as diesel engines, generators, propellers, air conditioners, fans and so on. Then, the SEA model of cruise ship is built by using VA One software, and the noise prediction of important cabins such as living and entertainment cabins and power equipment cabins are carried out. The spectrums of noise in those cabins are obtained, and compared with the limit value of IMO standard. The calculation results show that those cabins meet the requirements except the living room of four people. And it is found that the noise and vibration of the air conditioner room in the upper layer has great influence on the living room by analyzing the main noise sources of the living room. Then the different floating floors are applied to the air conditioner room to reduce noise of the living room. Through the comparative analysis the floating floor 2 and 3 have obvious effect of noise reduction on the living room. Finally, the acoustic characteristics of floating floor with different thickness of mineral wool are studied and there exists an optimal thickness. Related Articles | Metrics

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Impact Environment Prediction of Stiffened Cylindrical Shells based on Dynamic Substructure Method 2019, 39(1): 94-98.  DOI: 10.3969/j.issn.1006-1355.2019.01.018 Abstract ( )   PDF (1553KB) ( )   Related Articles | Metrics

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The Experimental Study on Tire Modal Analysis 2019, 39(1): 99-102.  DOI: 10.3969/j.issn.1006-1355.2019.01.019 Abstract ( )   PDF (1700KB) ( )   In order to optimize the tyre modal analysis experiment, and obtain the precise parameters of tire modal, by adopting LMS Test Lab, this paper studies the selection principle of measurement point layout、boundary constraint and incentive form. The results show that:(1)One single surface measuring easily lead to modal parameters lose and modal shape confusion, so it should be measure three tire surfaces (the inner、front and outer surface); (2)The high order modal shape is not clear with less than 36 points around the tyre circle, so there are arranged 36×3 points according to the 10° interval; (3) The tyre should be installed on the vehicle and free from the ground, the support displacement in this state is very small, this is better than soft rope constraint; (4) The signal coherence of exciter is 1 and it’s better than hammer, and it makes the experiment more convenient and efficient .This paper presents a new method for tyre modal testing, and obtain the precise parameters through this method. These results provide a fundamental basis for the noise and vibration control of tyre. Related Articles | Metrics

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Study on the Prediction Method of Off-road Average Speed of Tracked Vehicles on Random Uneven Roads QIAO Xinyong DUAN YU RUI Qiang JIANG Hongyuan YANG Hao 2019, 39(1): 103-109.  DOI: 10.3969/j.issn.1006-1355.2019.01.020 Abstract ( )   PDF (1773KB) ( )   In order to study the effect of road roughness on the off-road average speed of tracked vehicles, a multi-body dynamic model is established. The vibration response index is proposed and the credibility of the model is verified by the test. Based on the experimental design, a simulation model is made to establish the approximate model between vibration response and vehicle speed, road roughness. Taking the threshold value of the vibration response index as the constraint condition, the mathematical relationship between the roughness of the pavement and the speed of vehicle is fitted by the method of target optimization, and the prediction method of the off-road speed under the condition of random and uneven pavement is put forward. The method is used to calculate the test ground, and the results show that the model can reflect the impact of road roughness on the vehicle speed, and provide an effective quantitative means for vehicle mobility prediction. Related Articles | Metrics

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Correction of the Mirco-vibration Force Test on Clamped Mechanical Cryocoolers MA JUN 2019, 39(1): 110-115.  DOI: 10.3969/j.issn.1006-1355.2019.01.021 Abstract ( )   PDF (1491KB) ( )   Related Articles | Metrics

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Study on Matching Degree between Indoor and Outdoor Tests of Rolling Tire Noise on Rough Asphalt Pavements 2019, 39(1): 116-120.  DOI: 10.3969/j.issn.1006-1355.2019.01.022 Abstract ( )   PDF (1805KB) ( )   Rough asphalt pavement has a wide range of applications in China's highway construction. In order to reduce the dependence of the outdoor tire noise test on the bad weather, this paper compares the differences in indoor and outdoor tire noise spectra based on the tire noise test. The study found that all measuring points have a high degree of matching between the indoor and the outdoor test data when the vehicle operating condition is 50-20km/h gliding. Moreover, the frequency band is the typical tire noise frequency range of this pavement. When the vehicle operating conditions are uniform speeds of 20, 30, 40, and 50 km/h, the wheel noise data matching ratio is still higher while the one of interior noise data is poorly matched. Therefore, when the four-wheel drive drum test is performed under rough asphalt pavement, the right rear wheel data under 50-20 km/h gliding condition can be used as a good alternative to match the outdoor test noise data, thus reducing the dependence on harsh environments and the cost of the test and improving the test safety. Related Articles | Metrics

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A Modeling Method of Buffet for Flight Simulator Motion Systems 2019, 39(1): 121-125.  DOI: 10.3969/j.issn.1006-1355.2019.01.023 Abstract ( )   PDF (1564KB) ( )   Motion system is one of the main subsystems of the virtual environment of flight simulator. Buffet simulation is an important content of the motion system to improve the fidelity. A buffet model was established by the basic model of Sine-on-random vibration, combined with the acceleration power spectrum density(APSD) of aircraft flight test vibration data. Based on the APSD, an estimate method of buffet parameters was studied to calculate the parameters of the sine and random components. The vibration characteristics of typical flight conditions were analyzed, and an extraction method of influence parameters was studied to achieve the buffet model under full flight condition. Driven by the buffet parameters and the influence parameters, a modeling method for the buffet was proposed. The results show that this method can effectively simulate the buffet in flight simulator system. Moreover, it also provides reference for the construction of vibration environment in virtual reality technology. Related Articles | Metrics

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Influence of Contraction Amount on the Analysis of Static and Dynamic Characteristics of Automobile Suspension Bushings 2019, 39(1): 126-130.  DOI: 10.3969/j.issn.1006-1355.2019.01.024 Abstract ( )   PDF (1637KB) ( )   In order to effectively carry out the simulation research on the handling and riding performance of the vehicle, it is necessary to accurately design and control the static and dynamic stiffness ranges of the automotive suspension bushings with great influence. In this paper, the hyper-viscoelastic finite element model of a rubber bushing for an automotive suspension shock absorber is established using the 3rd order Ogden hyperelastic constitutive model and the 3rd order PRONY series viscoelastic model. The finite element analysis module ABAQUS/Standard is used to study the relationship between the size of the compression amount and the static and dynamic stiffness,the static and dynamic stiffness curves of the rubber bushings with different compression amount were obtained,which shows that when the compression amount is less than 0.6mm, the static and dynamic stiffness of the rubber bushing increases with the decrease of the compression amount and has an approximate linear relationship, when the compression amount is greater than 0.6mm, the static and dynamic stiffness increases with the decrease of the compression amount and the increasing rate increases sharply with a nonlinear relationship.The research shows that when compression amount reaches a certain level,the influence on the static and dynamic stiffness values of the rubber bushing becomes larger. Finally, the experimental results show that the relative error between the finite element analysis results and the test results is less than 10%, which proves the correctness of the static and dynamic characteristics analysis of the automotive suspension bushings considering the influence of the compression amount.has certain guiding significance for the design and analysis of the rubber bushings for vehicles.This has certain guiding significance for the design and analysis of rubber bushings for vehicles. Related Articles | Metrics

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Analysis of Vibration Characteristics of Steel Spring Floating Slabs in Low and Middle Frequency Ranges 2019, 39(1): 131-135.  DOI: 10.3969/j.issn.1006-1355.2019.01.025 Abstract ( )   PDF (2096KB) ( )   Related Articles | Metrics

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Analysis of the Vibration Reduction Performance of Steel Spring Floating Slab Track Bed of Chengdu Metro 2019, 39(1): 136-139.  DOI: 10.3969/j.issn.1006-1355.2019.01.026 Abstract ( )   PDF (1476KB) ( )   Related Articles | Metrics

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A Frequency Domain Approach for Dynamic Performance Analysis of Ballasted Track 2019, 39(1): 140-145.  DOI: 10.3969/j.issn.1006-1355.2019.01.027 Abstract ( )   PDF (1665KB) ( )   A three-layer continuously supported ballasted track model was built, and motion equations of the rail, sleeper and ballast were derived. By using the frequency domain analysis, the steady-state responses due to harmonic excitation were obtained. Then the wheel/rail interaction model in the frequency domain was introduced, and the wheel/rail force was solved based on the dynamic flexibility method. On the MATLAB platform, a program was compiled and the dynamic performance of ballasted track induced by track irregularities was solved in frequency domain. In the case study, the indexes of wheel/rail force, force transmissibility, track components vibrations were considered to assess vibration reduction effects of measures such as elastic fastener, soft baseplate under sleeper, composite sleeper, ballast mat and their combinations. Results show that vibration reduction measures can change the ballasted track’s natural frequency, and then cause the complexity of changing pattern of every index. Compared to the measure of elastic fastener, the soft baseplate under sleeper and ballast mat show a better comprehensive effect, while the composite sleeper has limited vibration reduction effect. Related Articles | Metrics

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Tri-directional Measurements and Analysis of the High-speed Train induced Ground-borne Vibration on a Viaduct of Chengdu-chongqing High-speed Railway 2019, 39(1): 146-150.  DOI: 10.3969/j.issn.1006-1355.2019.01.028 Abstract ( )   PDF (1548KB) ( )   Related Articles | Metrics

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Study onWavelet De-noising Parameters of Track Vibration Signal for Metro with the Train Traveling on at Low Speed 2019, 39(1): 151-155.  DOI: 10.3969/j.issn.1006-1355.2019.01.029 Abstract ( )   PDF (1250KB) ( )   Related Articles | Metrics

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Analysis of Performance and Frequency Response Characteristics of Fasteners for High-speed Railway 施何瑛 Lisa施何瑛 2019, 39(1): 156-159.  DOI: 10.3969/j.issn.1006-1355.2019.01.030 Abstract ( )   PDF (1416KB) ( )   Related Articles | Metrics

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Identification of Structural Mass and Model Free Nonlinear Restoring Forces with Partial Measurements 2019, 39(1): 160-165.  DOI: 10.3969/j.issn.1006-1355.2019.01.031 Abstract ( )   PDF (1918KB) ( )   Related Articles | Metrics

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Multi-faults Diagnosis Method for Gearboxes Based on SWD-AVDIF 2019, 39(1): 166-171.  DOI: 10.3969/j.issn.1006-1355.2019.01.032 Abstract ( )   PDF (2020KB) ( )   For the problem of multi-fault diagnosis of gearbox caused by noise interference and uneven distribution of fault intensity, a fault diagnosis method based on Swarm Decomposition-Average Difference Filter (SWD-AVDIF) was proposed. Firstly, Swarm Decomposition (SWD) is used to decompose the vibration signal into several Oscillatory Components (OCs), and then the OCs is demodulated into SWD-AVDIF spectrum with AVDIF operator to realize accurate diagnosis．Compared with EMD, The analysis results with simulation signal verify the superiority of SWD method in frequency discrimination ability; the method is applied to the mechanical multi-fault signal and the results show that this method can effectively decompose different fault signals and strengthen fault features, providing a new method for multi-fault diagnosis of gearbox. Related Articles | Metrics

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Early Fault Diagnosis of Rolling Bearings based on LMS and Fast-Kurtogram 2019, 39(1): 172-176.  DOI: 10.3969/j.issn.1006-1355.2019.01.033 Abstract ( )   PDF (1831KB) ( )   Related Articles | Metrics

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Structural Modal Parameter Identification based on Improved Complex Pursuit Algorithm 2019, 39(1): 177-185.  DOI: 10.3969/j.issn.1006-1355.2019.01.034 Abstract ( )   PDF (2607KB) ( )   Constant gradient based complexity pursuit (CP) is prone to fall into local extremum，and has slow convergence speed, and needs to choose the appropriate learning step for different model, which greatly limit the performance in practical application. To solve the defects above, the idea of optimal step is introduced into CP, automatically adjusting the step by the real-time degree of separation. At the same time, choosing different nonlinear function according to the kurtosis of the separated signal, CP can be employed in practical engineering effectively. To verify the practicability and reliability, the improved CP is applied in the structural modal parameters identification. The numerical models of concrete simply-supported beam and an experimental three-story-frame are built to demonstrate the accuracy of improved CP in structural modal identification. Related Articles | Metrics

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Dropping Damage Evaluation for Critical Components of Tilted Support Systems 2019, 39(1): 186-191.  DOI: 10.3969/j.issn.1006-1355.2019.01.03 Abstract ( )   PDF (2025KB) ( )   Dimensionless dropping shock dynamic equations of tilted support spring system with critical components were established and solved by adapting Runge-Kutta method. The system parameter, dropping shock initial velocity and the angle or the frequency ratio or the damping ratio were regarded as basic parameters and dropping damage boundary of critical components was obtained. Based on the numerical results, it demonstrates that decreasing the angle or increasing the frequency ratio can be contributed to expending the safe zone of critical components; the optimal damping ratio of the system exists and it is important to choose reasonably the damping ratio of the system for improving dropping shock resistance characteristics for tilted support spring system; vibration reduction and dropping shock resistance characteristics of the system can be obtained by considering comprehensively the stiffness coefficient of the product, the original length and relevant parameters. Related Articles | Metrics

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Fault Diagnosis of Gearbox Bearings based on KICA-GDA and LSSVM 2019, 39(1): 192-196.  DOI: 10.3969/j.issn.1006-1355.2019.01.036 Abstract ( )   PDF (1578KB) ( )   In order to achieve higher fault recognition rate of gearbox rolling bearing, a fault recognition method was proposed based on KICA (kemel independent component analysis)-GDA (generalized discriminant analysis) and LSSVM (least squares support vector machine). Firstly, fault features of rolling bearing vibration signal such as kurtosis and information entropy were computed and were recognized as initial feature vectors ,which were mapped into a kernel feature space with KICA to omit the redundancy and correlation among the fault features. Then the GDA was used to implement feature fusion and new features were inputted to LSSVM classifier for fault classification. The experimental results show the KICA-GDA and LSSVM method improves LSSVM’s classification performance by KICA-GDA obtaining additional discriminative information, and has more accurately rolling bearing fault classification than direct LSSVM method. Related Articles | Metrics

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Application of ODS in State Identification of Transformers 2019, 39(1): 197-200.  DOI: 10.3969/j.issn.1006-1355.2019.01.037 Abstract ( )   PDF (1616KB) ( )   Related Articles | Metrics

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Damping Characteristics of Large-section Conductors for UHV DC Projects 2019, 39(1): 201-204.  DOI: 10.3969/j.issn.1006-1355.2019.01.038 Abstract ( )   PDF (1543KB) ( )   Related Articles | Metrics

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Prediction of the Damping Efficiency of Constrained Damping Structures by Finite Element Method jun xianwu 2019, 39(1): 205-209.  DOI: 10.3969/j.issn.1006-1355.2019.01.039 Abstract ( )   PDF (1252KB) ( )   Related Articles | Metrics

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Low Frequency Bandgap Characteristics of Four-Fold-Beam Phononic Crystals 2019, 39(1): 210-215.  DOI: 10.3969/j.issn.1006-1355.2019.01.040 Abstract ( )   PDF (2619KB) ( )   A kind of two-dimension four fold beam phononic crystal was proposed. Multiple vibration coupling mechanism is the key to low frequency bandgap. Low frequency bandgap characteristics and corresponding geometric parameters effects were analyzed by a finite element method. It is found that the increase of geometric parameters(width of four fold beam) can lead to the bandgap disappearances. Joint geometry sizeandbetween four fold beam and matrix materials have the same effect on the variation of bandgap, and increase of these can only make the first bandgap move to the low frequency range. Different combination forms of big original cell can unfold or close the bandgap. Design ideas and related theory enriched the phononic crystal studies, and could provide theoretical guidance for the design of the structure of the phononic crystal, the multi resonance phenomenon in the ultra low frequency range shows that the phononic crystal structure in this study has potential applications in the low frequency energy recovery. Related Articles | Metrics

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Analysis of Influences of theWorm Tongue Structure Type on the Internal Aerodynamic Actuation of Centrifugal Ventilators Dingkejin 2019, 39(1): 216-220.  DOI: 10.3969/j.issn.1006-1355.2019.01.041 Abstract ( )   PDF (4116KB) ( )   Worm tongue is an important component of the centrifugal ventilator. To investigate its influences on the vibration noise of the centrifugal ventilator, numerical simulation is conducted for the aerodynamic actuation of a certain centrifugal ventilator. Through steady computation, it is found that the structure improvement can help to reduce local vortex, which is an important factor contributing to vibration. Through unsteady simulation, it is verified that the impact of the worm tongue structure on the aerodynamic actuation is mainly featured by the amelioration of local pressure fluctuation, especially the decrease of the fluctuation at blade frequency intrigued by the outflow from impeller. Based on the numerical results for the model machine, evaluation on the variation of the vibration noise is made. The results show that improvement of the worm tongue structure is beneficial to the reduction of the vibration noise; Numerical analysis for aerodynamic actuation can provide judgments to evaluate the effectiveness of the low-noise improvement of the ventilator. Related Articles | Metrics

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Selection of Soundproof Pads of Automobile Dash Panels based on Acoustic Transfer Function 2019, 39(1): 221-223.  DOI: 10.3969/j.issn.1006-1355.2019.01.042 Abstract ( )   PDF (1051KB) ( )   Related Articles | Metrics

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Research on Correlation between Transmission Loss and Impedance of Complex Mechanical Isolation Systems wu wuhui 2019, 39(1): 224-229.  DOI: 10.3969/j.issn.1006-1355.2019.01.043 Abstract ( )   PDF (1701KB) ( )   The complex mechanical system consists of elastic elements and rigid components. In the steady operation state of complex mechanical systems, the multi-system impedance of elastic elements and rigid elements is the main factor that affects the system vibration isolation and transmission loss. In this article, a double-layer vibration isolation mechanical system was developed, and two kinds of system impedance mathematical models were established by the test method of type B&K8203 excitation hammer and type B&K 3660D measurement collection system to obtain the initial impedance of complex mechanical system which was used as a reference. By adjusting the structural strength of the mechanical system base and the supporting stiffness of the piping system, the relationship between the system impedance of the two types and the vibration isolation effect of the mechanical system and the transmission loss of the pipeline system were studied. The quantitative relation between the vibration isolation system of double-layer vibration isolation mechanical system and the transmission loss of pipeline and the system impedance of two types was obtained. The experimental results showed that: 1.The appropriate increase of the system impedance of the base was beneficial to the vibration isolation effect of the vibration isolation device. Concerning the system with weak base impedance, if the vibration isolation effect of vibration isolation system fails to meet the design requirement, the appropriate increase of the impedance of test base is an effective solution to satisfy the vibration isolation effect. 2.By changing the properties and installation layout of the flexible components of the piping system, the transmission loss the vibration energy of the flexible piping system can be increased, reducing the base level of vibration isolation system effectively and increasing the vibration isolation effect of the system. Related Articles | Metrics

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Vibration Response of Miura Folded Meta-materials under Harmonic Excitations Zhang Dapengsdf Zhou NoneXiang 2019, 39(1): 230-234.  DOI: 10.3969/j.issn.1006-1355.2019.01.044 Abstract ( )   PDF (2055KB) ( )   Folded metamaterials are based on the development of folding structures and have extraordinary physical properties. ADAMS was used to analyze three typical structural models. Under the simple harmonic excitation of force and displacement, different crease stiffness affected the vibration response of Miura folded metamaterials. The results show that the Miura model with single-degree-of-freedom structure has a similar frequency response under two kinds of excitation, and the resonance frequency can be changed by changing the crease stiffness, which can achieve a good low-frequency isolation effect. The multi-degree-of-freedom model can reduce the resonance frequency by increasing the number of stack. It provides a theoretical reference for the vibration isolation design of Miura folding structure. Related Articles | Metrics

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A Measurement Method of Power Flow Transmission for Multi-supported Vibration Isolation Systems 2019, 39(1): 235-237.  DOI: 10.3969/j.issn.1006-1355.2019.01.045 Abstract ( )   PDF (1676KB) ( )   A testing platform of power flow was built, and an indirect method for testing power flow was used in multi-vibration isolation systems. The effectiveness of the indirect testing method was verified by comparing power flow transmission of vibration isolation systems obtained by direct and indirect methods. This method avoids the problem that the force signal is difficult to obtain in traditional test method of power flow of vibration isolation systems. Indirect test method for power flow is easier to implement. It has reference value for the acquisition of the power flow of vibration isolation systems and related structures in the engineering. Related Articles | Metrics

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The Mechanism and Application of Electromagnetic and Permanent Magnet Vibration Assisted Grinding Keven KevenKeven 2019, 39(1): 238-244.  DOI: 10.3969/j.issn.1006-1355.2019.01.046 Abstract ( )   PDF (1987KB) ( )   Related Articles | Metrics