506 results
Search Results
2. Vibration diagnostics of small hydroelectric power station machinery
- Author
-
Elias Tomeh and Martin Mazac
- Subjects
Engineering ,Bearing (mechanical) ,Power station ,business.industry ,Water flow ,Materials Science (miscellaneous) ,Short paper ,Mechanical engineering ,Turbine rotor ,Turbine ,Industrial and Manufacturing Engineering ,law.invention ,Vibration ,Hydroelectricity ,law ,Business and International Management ,business ,Marine engineering - Abstract
This short paper describes a problematic of a small hydroelectric power station machinery vibration diagnostics. The vibration diagnostics of a power station machinery is very specific, machinery contains many possible damaged rotating parts including a turbine rotor. Non-stationary strength pulsing caused by water flow can be generated. The paper describes problems with the correct determination of a small hydroelectric power station machinery failure.
- Published
- 2017
3. Statistical analysis of turbo generator sets failure causes.
- Author
-
Babin, Alexander, Polyakov, Roman, Savin, Leonid, and Tyurin, Valentin
- Subjects
STATISTICS ,FAILURE mode & effects analysis ,ELECTRIC generators ,MECHANICAL engineering ,TURBINE generators ,ARTIFICIAL neural networks ,SYSTEM failures ,FORECASTING - Abstract
Failure diagnostics and general decrease of accident rate at power plants is a major task of energy generation industry, and solution of it provides reliable energy supply country wide and technological progress in mechanical engineering. Along with some other crucial means, the task could be solved by means of teaching the maintenance staff based on accidents that have already occurred. That is no secret that everywhere in the world due to indecision or misinterpretation a huge number of accidents have happened merely because the personnel were not aware of similar cases at other power plants. Nevertheless with the development of computational technologies and mathematical algorithms the role of personnel in some cases has been reduced to observation and action in critical situation, while the rest is performed by machines: various types of diagnostics and prediction of failure systems based on artificial neural networks are widely applied and developed. However, in order to train these systems, it is absolutely required to know the reasons that could lead to and consequences that could follow some deterioration in turbo generator sets performance. The aim of the present paper is to give statistical analysis of turbo generator sets failure reasons based on open source data presented by Russian and foreign researchers and analysts in the field. The statistical data could be used to perform classification and ranking of failure reasons in terms of frequency of occurrence, possibility to identify or detect, etc. and the paper also gives brief listing of possible ways of detection or identification of failure modes and possible consequences for the main units of a turbo generator. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
4. Practical implementation and experimental testing of control system for vibratory lapping-polishing machine.
- Author
-
Kachur, Oleksandr, Korendiy, Vitaliy, Zakharov, Viktor, Borovets, Volodymyr, Havrylchenko, Oleksandr, and Palash, Roman
- Subjects
- *
MECHANICAL engineering , *TEST systems , *MACHINE parts , *MACHINING , *MACHINERY , *GRINDING & polishing - Abstract
Vibratory technological machines are widely implemented in various branches of industrial, manufacturing, and mechanical engineering. Particularly, such equipment can be effectively used while conducting finishing technological operations, e.g., lapping and polishing of different machine parts. The present paper is focused on developing the control system for the novel design of a vibratory lapping-polishing machine driven by six solenoids. The main purpose consists in providing the circular trajectory of the working member and ensuring the machining uniformity at each point of the surface being treated. In such a case, it is proposed to actuate the solenoids with the specified time shift depending on the forced frequency needed to be provided. The duration of the signal actuating the solenoid is equal to one-sixth of the total duration of a cycle (period) of the working body oscillation. The corresponding control approach is developed and simulated in the Tinkercad application, while the control system is designed based on the Arduino software and hardware. In addition, the laboratory prototype of the vibratory lapping-polishing machine and the corresponding control system are implemented in practice. The performed experimental investigations substantiate the possibilities of generating the circular oscillations of the working member of the vibratory lapping-polishing machine. The obtained results may be useful for engineers and technologists dealing with control systems of various vibratory technological equipment based on electromagnetic and solenoid-type drives. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
5. Research of synchronization of pneumatic vibroexciters operating on air-cushion with feeding pulsatile pressure.
- Author
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Pauliukaitis, Darius, Kibirkštis, Edmundas, Vaitasius, Kęstutis, and Ragulskis, Kazimieras
- Subjects
MECHANICAL engineering ,VIBRATION (Mechanics) ,PULSATILE flow ,AERODYNAMICS ,AIR cushions - Abstract
A synchronization method of pneumatic actuators operating in autovibration mode and fed by pulsatile pressure has been investigated. A mathematical model was analysed numerically describing the dynamics of two vibroexciters connected through aerodynamic channel. The effect of parameters of pulsatile feed pressure on shapes of vibrations of vibroexciter's working body has been determined. Values of geometrical and dynamical parameters at which synchronization of the mechanical system takes place have been determined. In this case, actuator's movement law can be both harmonic and non-harmonic in case of pulsating amplitude. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
6. A dynamic analysis of six-bar mechanical press.
- Author
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Mukasheva, Assel, Japayev, Saduakhas, Abdraimova, Gulnara, Kyrykbaev, Batyrkhan, Kozhamberdiyev, Kuatbek, Uskembayeva, Bagdat, and Zhauyt, Algazy
- Subjects
METALWORK ,MECHANICAL engineering ,DYNAMICS ,TECHNOLOGICAL innovations ,COMPUTERS in engineering - Abstract
This paper analyzes the dynamical behavior of a six-bar linkage used in mechanical presses for metal forming such as deep drawing. Raising the technical level of machines requires an expansion of technological capabilities of the equipment and devices of the existing structures, as well as their equipping with fundamentally new mechanisms. In this regard, the task of developing methods for the dynamic of complex flat lever mechanisms with the desired laws of motion of the input and output elements allowing automatizing the implementation of all design phases with the use of computer is quite relevant. The simulation results obtained with a Maple program are validated by comparing the theoretical values of the input moment with the ones obtained from the conservation of energy law. Content of the article is distinguished by serious problem statement, interesting theoretical study and its practical test. This article provides new scientific results that have theoretical and applied significance. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
7. Research on damage mechanism of bearing current in high power motor.
- Author
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Guangbin Wang, Long Li, and Xianwen Meng
- Subjects
- *
PHYSICAL & theoretical chemistry , *CORRUGATED boxes , *MECHANICAL ability , *MECHANICAL engineering , *BEARING currents in electric machinery - Abstract
In the running process of high power motor, the shaft voltage and bearing current are sometimes present. Under the combined action of the current and the mechanical load, the corrugated groove is formed on the bearing race. The paper analyzed the causes, forms and characteristics of the early current damage of bearing, studied the relationship between the number of shaft current size and bearing pitting attack damage, presented the theoretical calculation method of the corrugated groove, got the change rule of the corrugated groove spacing with the change of the motor speed and the mechanical load. The experimental results are in agreement with the theoretical analysis, the measurement value of corrugated groove average spacing is very close to its theoretical value, and the average deviation is less than 10 %. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
8. Problems of precise vibromechanics and vibroengineering.
- Author
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Pauliukaitis, Darius, Kibirkštis, Edmundas, and Ragulskis, Kazimieras
- Subjects
VIBRATION (Mechanics) ,MECHANICAL engineering ,INVENTIONS ,TECHNOLOGICAL innovations ,PRECISION (Information retrieval) - Abstract
A review on investigations of precise vibromechanics and vibroengineering performed in Lithuania is presented in this paper. Results of research, inventions and innovations obtained in this field are discussed. Some of the development in the area of precise vibromechanics are presented in more details. [ABSTRACT FROM AUTHOR]
- Published
- 2016
9. Developing system of automatic control resonant mode of a vibrating machine.
- Author
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Krestnikovskiy, Konstantin V., Panovko, Grigory Ya., and Shokhin, Alexander E.
- Subjects
OSCILLATIONS ,AUTOMATIC control systems ,MECHANICAL engineering ,ROTOR vibration ,PHASE shift (Nuclear physics) ,NUCLEAR excitation - Abstract
The paper is devoted to the experimental check of a control algorithm for automatic adjustment of oscillations of a mechanical system to the resonance mode. Oscillations of the system are excited by rotating an unbalanced rotor of an asynchronous electric motor. Working principle of the control system is based on measuring a phase shift between oscillations of the system and an excitation force. [ABSTRACT FROM AUTHOR]
- Published
- 2016
10. Vibration of string lattice.
- Author
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Astashev, Vladimir, Andrianov, Nikolay, and Krupenin, Vitaly
- Subjects
VIBRATION (Mechanics) ,STRING ,CRYSTAL lattices ,MECHANICAL engineering ,DIMENSIONS - Abstract
A two-dimensional system oscillation with massive bodies located in lattice nodes is investigated in this paper. The results of theoretical analysis and of the performed experiments are given. Certain modes of the oscillation of lattices of different dimensions are described. [ABSTRACT FROM AUTHOR]
- Published
- 2016
11. Modeling and dynamic analysis of hydraulic damping rubber mount for cab under larger amplitude excitation.
- Author
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Xin Liao, Xiaojuan Sun, and Hu Wang
- Subjects
- *
RUBBER , *DYNAMIC models , *HYDRAULIC models , *REFERENCE values , *ANALYTICAL solutions - Abstract
In order to improve the ride comfort of the cab of construction machinery and reduce the harm of vibration to the driver, the lumped parameter model of passive hydraulic damping rubber mount (PHDRM) considering the nonlinearity of multi-inertial tracks is first established. Then the overall FE (finite element) fluid-solid coupling model of the vibration isolator is proposed by using ABAQUS combined simulation mode in this paper. Meanwhile, Combined with bidirectional strong coupling algorithm, the parameters of the rubber main spring and inertial track are identified respectively. Also, the dynamic characteristic experiments of the PHDRM samples are carried out. The experiment results show that the analytical solution and FE modeling method of the HDRM system are reliable and accurate under larger amplitude excitation. On the basis of this, the effects of the rubber main spring and inertial track of PHDRM on low frequency dynamic characteristics under larger amplitude excitation are respectively analyzed and discussed. It provides practical reference value for nonlinear modeling method research and dynaimc performance analysis of PHDRM with complex structure further. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
12. An experimental measurement and numerical calculation method on friction temperature rise of sliding contact pairs - taking rail/wheel contact as an example
- Author
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Yunpeng Wei, Yaping Wu, and Zhidong Chen
- Subjects
Mechanical Engineering ,Materials Science (miscellaneous) ,Instrumentation - Abstract
The analysis of rail/wheel sliding friction heat is a very important research field. The numerical simulation is often adopted to calculate the friction heat, and experimental method is relatively few. In this paper, an experimental machine is designed to simulate the rail/wheel sliding contact. At the same time, a rail/wheel contact wear model and a friction heat transfer model are established. The characteristics of temperature on rail/wheel sliding contact are analyzed by experimental test and numerical calculation. The research results show that the temperature rise of wheel and rail is quick in the initial sliding contact stage, then gradually slows down. The temperature of wheel is higher than that of rail at the same depth from the contact surface. In the initial sliding stage, the wheel temperature rises faster than the rail temperature, which is related to the size of contact surface and the concentration degree of friction heat. Moreover, the results of this paper show that the temperature values of the rail/wheel obtained through experimental test and numerical calculation are in good agreement. The experimental and numerical calculation methods used in this article can be adopted to analyze the contact problems of other sliding friction pairs.
- Published
- 2023
13. Analysis of longitudinal and torsional vibration of mining scraper conveyor under the over bending section working condition
- Author
-
Chunxue Xie, Zhixiang Liu, and Miao Xie
- Subjects
Mechanical Engineering ,General Materials Science - Abstract
Considering that the scraper will produce longitudinal and torsional pendulum vibration when passing through the bending section, and have a great influence on the motion characteristics of the scraper conveyor, this paper studies the longitudinal and torsional pendulum coupling vibration characteristics of the scraper conveyor under the working condition of over-bending section for the first time. Firstly, the simplified model of torsional pendulum vibration of scraper chain system is established based on Voigt model and point-by-point tension method. Then, the change law of scraper group vibration and chain tension under the condition of scraper bending is studied. Thirdly, through the influence area and attenuation characteristics of torsional pendulum vibration, the thumbnail model of torsional pendulum vibration is constructed. Finally, the longitudinal and torsional pendulum coupling vibration dynamic model of the scraper chain system is constructed based on the torsional pendulum vibration abbreviation model, and the overall longitudinal and torsional pendulum vibration characteristics of the scraper conveyor are studied when the scraper is over the bending section. The conclusion of this paper provides a theoretical basis for better understanding the operation characteristics of scraper conveyor in coal mine.
- Published
- 2023
14. Research on rock breaking characteristics of impact hob of hard rock excavator
- Author
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Lei Lou, Xiao Wang, Wanrong Wu, and Weiye Qin
- Subjects
Mechanical Engineering ,General Materials Science - Abstract
During hard rock excavation in the process of tunnel construction, the hard rock excavator wears seriously and quickly and reduces its excavation efficiency. Aiming at this problem, this paper proposes a composite rock breaking method by impact rolling and cutting as a solution. In this paper, the composite rock breaking characteristics of impact hob are studied. The impact cutting load of the hob was analyzed, and the hobbing force equation and the rock crushing volume equation were established. The effects of different impact frequencies and impact loads on the cutting force and rock crushing characteristics of the hob were analyzed by experiments. The results show that under a certain thrust and hob spacing, with the increase of the impact frequency, the rock ridge between the two hobs gradually decreases, while the crushed volume of the rock increases gradually. Under the same axial load and cutter spacing conditions, with the increase of the impact frequency, the hob shear force decreases significantly. Under a certain axial load and impact frequency, with the increase of impact load, the crushing volume of rock and the hob shear force decrease significantly. These test results are of great significance for guiding the efficient excavation of hard rock tunnels.
- Published
- 2023
15. Experimental investigation of unbalance and misalignment in rotor bearing system using order analysis.
- Author
-
Mogal, S. P. and Lalwani, D. I.
- Subjects
ROTOR bearings ,FAULT tolerance (Engineering) ,ROTATING machinery ,VIBRATION (Mechanics) ,MECHANICAL engineering - Abstract
Unbalance and misalignment are the main causes of vibration in rotating machinery. Vibration analysis is the important tool for fault diagnosis in rotating machinery. In this paper, order analysis technique of vibration analysis for unbalance and misalignment fault diagnosis is proposed. In order analysis, both phase and amplitude are obtained. From phase and amplitude, the fault type and location are usually identified. Experimental results show order analysis is an effective technique for fault diagnosis. [ABSTRACT FROM AUTHOR]
- Published
- 2015
16. Real-time LabVIEW application for diagnostics and evaluation of machine vibration.
- Author
-
Listewnik, Karol, Grzeczka, Grzegorz, Cioch, Witold, and Kłaczyński, Maciej
- Subjects
VIBRATION (Mechanics) ,PARAMETER estimation ,MECHANICAL engineering ,VIRTUAL instrumentation ,INTERNAL combustion engines - Abstract
The paper describes the algorithm and real-time software application named "VibroTest", created in National Instruments LabVIEW Environment for determine the status of the machine based on the standard ISO 10816-1 Mechanical vibration. Evaluation of mechanical vibration by measurements on non-rotating parts - part 1: General guidelines [1]. The study includes the methods of the measurement, the concepts of the measurement system and the method of the calculation. [ABSTRACT FROM AUTHOR]
- Published
- 2015
17. Parameter estimation of underwater propeller based on inverse Radon transform
- Author
-
Tang Bo, Zhang Linsen, and Tan Siwei
- Subjects
Mechanical Engineering ,Materials Science (miscellaneous) ,Instrumentation - Abstract
Aiming at improving the method of underwater target recognition, this paper proposes a method to estimate the micro-Doppler spectrum parameters of propeller by using inverse Radon transform, so as to obtain the characteristic parameters of propeller. This paper firstly analyzes the basic concepts of micro-Doppler and inverse Radon transform, then defines the algorithm steps of inverse Radon transform for propeller parameter estimation and carries out simulation. The simulation results show that this method can effectively estimate the propeller rotational speed, blade number, blade length and initial spatial position.
- Published
- 2022
18. Active noise control method of power communication signal based on BP neural network
- Author
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Dongbing Yuan and Yue Zhang
- Subjects
Mechanical Engineering ,General Materials Science - Abstract
In the power line communication network, the electrical node switch connected to the Power Line Communication network will affect the impedance, noise and signal attenuation of the network. The connection change between the network nodes will lead to the change of the topology structure. This paper proposes a new type of automatic modulation pattern recognition system assisted by blind channel recognition based on a convolutional neural network, which is composed of two convolutional neural networks with different architectures, and successfully improves the recognition accuracy of the traditional automatic modulation pattern recognition system. The Signal to Noise Ratio recognition rate of the proposed blind channel recognition assisted Adaptive Multi-Rate system is as high as 99 %, which is more than 5 % higher than that of other comparison methods. After several iterations, the accuracy and loss function of the model studied in this paper are still at a stable level. The intelligent recognition technology of blind signals proposed in this paper can effectively improve the interference problem of communication signals in power system and has a promotion effect in other communication systems, which can achieve higher technical application value.
- Published
- 2022
19. An on-line monitoring method for the flow excitation in francis hydraulic turbine based on dynamics
- Author
-
Zhaojun Li, Guangzheng Zhang, Fuxiu Liu, and Jiaquan Chen
- Subjects
Mechanical Engineering ,General Materials Science - Abstract
During the operation of hydraulic turbine, the vibration often exceeds the standard due to flow excitation, which affects the safe and stable operation of the hydraulic turbine. In this paper, an on-line monitoring method for the flow excitation in Francis hydraulic turbine is proposed based on the dynamic characteristics of Francis hydraulic turbine. Firstly, based on the flow excitation characteristics in Francis hydraulic turbine and the dynamic equation of main shaft system, the internal relationships between the dynamic response of turbine bearing and the flow excitation in the Francis hydraulic turbine are clarified. Secondly, according to these relationships, a method based on wavelet transform (WT), particle swarm optimization (PSO), and variational mode decomposition (VMD) is proposed for extracting the flow excitation features in Francis hydraulic turbine. Then, by this method, the flow excitation features are acquired. Based on the obtained flow excitation features, the flow excitation can be monitored on-line. Finally, the proposed on-line monitoring method for the flow excitation in Francis hydraulic turbine is verified by experiments. Based on the results, the flow excitation components in the signal extracted by this method are about 35 % more than those extracted by the previous methods. The results show that the on-line monitoring method proposed in this paper is convenient and effective.
- Published
- 2022
20. 1032. A new transient field balancing method of a rotor system based on empirical mode decomposition.
- Author
-
Guangrui Wen, Tingpeng Zang, Yuhe Liao, and Lin Liang
- Subjects
- *
TRANSIENT analysis , *ROTORS , *EMPIRICAL research , *DECOMPOSITION method , *MECHANICAL engineering , *STEADY-state flow , *VIBRATION (Mechanics) - Abstract
Effective reduction of the vibration in rotor and stator at critical speed is important for steady operation of rotor systems. A new transient field balancing method is proposed in this paper. The empirical mode decomposition (EMD) method coupled with holospectral technique is used to extract rotating frequency information including precise frequency, amplitude and phase nearby the critical speed from the run-up vibration signals. Reasonable trial weights are selected through estimating the unbalance masses and position. Moreover, the correction masses and position are obtained by holo-balancing method. Compared with the traditional dynamic balancing method, this method does not need obtain steady-state vibration signals, and the rotor can pass through the critical speed smoothly. The principle and detailed procedures of this method are described in this paper, and the effectiveness of the new method was validated by field balancing of rotor kit system. [ABSTRACT FROM AUTHOR]
- Published
- 2013
21. Traffic signal light detection and recognition based on canny operator
- Author
-
Liu Yuming and Guo Shuqing
- Subjects
edge detection ,traffic signal light ,business.industry ,Computer science ,Mechanical Engineering ,Materials Science (miscellaneous) ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,Image processing ,HSL and HSV ,Color space ,simulation ,Grayscale ,Edge detection ,image processing ,Computer Science::Computer Vision and Pattern Recognition ,canny operator ,Canny edge detector ,T1-995 ,RGB color model ,Computer vision ,Artificial intelligence ,business ,Instrumentation ,Technology (General) ,Histogram equalization - Abstract
In this paper, five classical edge detection operators are compared, and then a traffic signal light detection and recognition scheme that can be used for intelligent connected vehicles is implemented. Firstly, the image to be processed is obtained by detecting the traffic signal light through the vision sensor. The image is preprocessed: the color space of the image is converted from RGB space to HSV space. Through the grayscale, histogram equalization, image binarization processing, using the morphological closure operation, the five operators are compared in noise sensitivity, positioning accuracy and signal-to-noise ratio, the Canny edge detection operator is selected for image edge detection, and the target recognition area is obtained. Finally, using the histogram drawn, the number of red, green and yellow pixel points in the histogram can be clearly counted, and the color with the largest number of pixel points can be identified as the color of the identified traffic signal light, and the identification of the traffic signal light can be completed. The actual pictures are simulated on the MATLAB, which verifies the feasibility of the proposed method of traffic signal light recognition method based on Canny operator in this paper, which can correctly identify the color of the traffic signal light.
- Published
- 2021
22. 2783. Dispersed operating time control of a mechanical switch actuated by an ultrasonic motor.
- Author
-
Xiaoniu Li, Zhiyuan Yao, Lifeng Zhou, and Shengli Zhou
- Subjects
- *
ACTUATORS , *ACTUATOR testing , *ULTRASONIC motors , *VIBRATION (Mechanics) , *MECHANICAL engineering , *MATHEMATICAL models - Abstract
The ultrasonic motor is an uncertain time-varying nonlinear system because of the nonlinearity of the piezoelectric material, the friction and the temperature. For example, the operating time of the mechanical switch actuated by the ultrasonic motor in regular stroke is highly dispersed. Unfortunately, it is difficult to establish accurate mathematical model. In this paper, an analytical autoregressive process model (AR) is employed to identify and control the ultrasonic motor. First of all, dispersed operating time of the mechanical switch actuated by the ultrasonic motor is investigated. Then, the AR model is established to predict the operating time of the ultrasonic motor on the basis of the statistical data to reduce the nonlinear behavior of the ultrasonic motor, and to improve the accuracy and obtain a good time response of the switch. The simulation results are agreed with experimental results, confirming the effectiveness of proposed model. Furthermore, we adopt the predicted result of the AR model to control the mechanical switch actuated by the ultrasonic motor. The analytical investigation is fulfilled with two target operating time ranges, namely 12 ms and 24 ms. Comparison of the results obtained from the AR model and the experimentation reveal that the standard deviations are less than 95.3 μs and 102.7 μs with maximum errors equal to 0.41 % and 0.44 % respectively. Thereby, the proposed dispersed operating time control is performed. Findings indicate that the maximum errors for the operating time of the mechanical switch are less than 140 μs and 110 μs with ±0.85 % and ±0.42 % respectively. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
23. Study on new method for modal parameters identification of stiffened plate with four clamped edges.
- Author
-
Ma Tian Bing, Du Fei, and Liu Jian
- Subjects
- *
KINETIC energy , *RAYLEIGH-Ritz method , *CALCULUS of variations , *MECHANICAL engineering , *ANSYS (Computer system) - Abstract
In order to accurately and rapidly identify the vibration characteristic parameters of nonlinear stiffened plate structure, Rayleigh-Ritz method is used for modeling. First, the stiffened plate with four edges clamped is divided into plate and stiffeners. The plate is considered to be geometrically nonlinear, and the stiffeners are taken as Euler beams to solve the deformation energy and kinetic energy. Then, natural frequency of stiffened plate is solved by Rayleigh-Ritz method. Finally, stiffened plate structure in the laboratory is selected as the research object, results from Rayleigh - Ritz method calculation are compared with ANSYS and the swept frequency method results. The results show that the solution in this paper can be correct, which lays a good foundation for further nonlinear active control experiment. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
24. Ensuring the chatter stability of milling by optimizing the workpiece stock
- Author
-
Sergey A. Voronov, Igor Kiselev, and Vladimir Kuts
- Subjects
Optimization algorithm ,Computer Science::Computational Engineering, Finance, and Science ,Computer science ,Materials Science (miscellaneous) ,Stability (learning theory) ,Mechanical engineering ,ComputerApplications_COMPUTERSINOTHERSYSTEMS ,Sensitivity (control systems) ,Business and International Management ,Industrial and Manufacturing Engineering ,Stock (firearms) ,Finite element method ,Analysis method - Abstract
The paper considers a new technique for increasing the dynamic stability of the dynamics of milling flexible parts. The technique is based on the formation of a uniform stock of the workpiece for the finish milling. The paper proposes an optimization algorithm for the automated calculation of the stock distribution based on the sensitivity analysis method. The ratio of the natural frequencies of the flexible workpiece is used as the objective function of the optimization algorithm. The developed technique was tested on a numerical example.
- Published
- 2021
25. The influence of structural configurations and operating speeds on the sorting arm during high frequency reciprocating operation
- Author
-
Ying Li, Biao Zhang, Hu Zhang, and Xuchu Jiang
- Subjects
Frequency response ,Frequency band ,Computer science ,Mechanical Engineering ,high-frequency reciprocating operation ,Sorting ,dynamics ,02 engineering and technology ,configurations ,01 natural sciences ,Vibration ,operational modal analysis ,Acceleration ,Operational Modal Analysis ,Reciprocating motion ,020303 mechanical engineering & transports ,strain modal analysis ,0203 mechanical engineering ,Control theory ,0103 physical sciences ,TJ1-1570 ,General Materials Science ,Mechanical engineering and machinery ,Operating speed ,010301 acoustics - Abstract
Under high-frequency reciprocating operation, the dynamics of the sorting arm are different between operating status and standstill status. First of all, the energy of inertial impact and frequency band depend on the actual motion state, which are closely related to the dynamics of the arm structure. Secondly, during the high-frequency reciprocating operation, the positions of sorting arm change, which causes its configurations changes. At the same time, the acceleration and deceleration in each stage of operation are also inconsistent. These factors make the vibration of the sorting arm structure more complicated. Therefore, the dynamics of the sorting arm mechanism must be analyzed under the actual operating conditions. The paper takes the sorting arm of LED chip sorter as the research object, and it is pointed out that the sorting arm structure has the characteristics of multi-mode high-low frequency during operation. However, the structural configurations and operating parameters of the sorting arm are the main influencing factors of its vibration, which have different characteristics of the high-low frequency response. In this paper, the use of sequential sub-section design to determine the configurations and the corresponding time-series during the operation. Through the analysis of multi-mode frequency response of the sorting arm, the characteristics of high-low frequency range corresponding to the two kind of work excitation are obtained. This paper verifies that the dynamics of the sorting arm are affected by the excitation of structural configurations and the excitation of operating speed during high-speed operation. The laws of high-low frequency response of the sorting arm under different operation parameters and configurations are found out, which provides guidance for the vibration suppression of the sorting arm under operation.
- Published
- 2021
26. Erratum: Design and application of fuel injection drive circuit for engine test bench.
- Author
-
Baoqing Deng, Yuchuan Jia, Zhang Bo, Zhenyu Deng, and Zengfa Gao
- Subjects
ENGINE testing ,BENCHES ,AEROSPACE engineering ,MECHANICAL engineering ,AEROSPACE engineers ,EMAIL - Published
- 2021
- Full Text
- View/download PDF
27. A review on wind turbines gearbox fault diagnosis methods
- Author
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H. Gu, Q. W. Gao, W. Y. Liu, and Y. Zhang
- Subjects
Computer science ,condition monitoring ,lcsh:Mechanical engineering and machinery ,02 engineering and technology ,Fault (power engineering) ,01 natural sciences ,Turbine ,Automotive engineering ,0203 mechanical engineering ,wind turbine gearbox ,0103 physical sciences ,lcsh:TJ1-1570 ,General Materials Science ,010301 acoustics ,Downtime ,Wind power ,business.industry ,feature extraction ,Mechanical Engineering ,Condition monitoring ,Failure rate ,fault diagnosis ,Renewable energy ,020303 mechanical engineering & transports ,business ,Communication channel - Abstract
As an renewable and clean energy of the world, wind energy has gained more and more attention and its fault diagnosis becomes more and more important. The gearbox, as the kernel component of the wind turbine system, it’s robust conditions have a great influence on the whole wind turbines system. Wind turbine gearbox has complex structure, which is usually composed of solar planetary gearbox and cylindrical gearbox. In the process of operation, various kinds of faults easily occur, resulting in serious losses. Once the wind turbine gearbox is not functioning as smoothly as it could be, it may result in large economic losses for the company and owner. At the same time, the failure rate of wind turbine gearbox has always been high because of complicated mechanic structure and special motion. Therefore, the tasks of reducing the downtime and increasing the productivity of wind turbine gearbox are urgent. This paper reviewed some research results of faults diagnosis on wind turbines gearbox, such as time-frequency analysis method, vibration based methods, nondestructive testing methods, etc. Meanwhile, this paper finds out some key problems and the channel of the resolution of the issue in order to supply some information for the further research of wind turbines gearbox.
- Published
- 2021
28. The seismic analysis and performance of steel frame with additional low-yield-point steel dampers
- Author
-
Akin-Adewale Adedamola, Pan Huali, Ou Guoqiang, Azka Amin, and Muhammad Akbar
- Subjects
nonlinear time history analysis ,seismic performance ,Modal analysis ,Shear force ,02 engineering and technology ,01 natural sciences ,Seismic wave ,Damper ,Seismic analysis ,pushover analysis ,0203 mechanical engineering ,0103 physical sciences ,TJ1-1570 ,General Materials Science ,Mechanical engineering and machinery ,010301 acoustics ,business.industry ,Mechanical Engineering ,Structural engineering ,Finite element method ,steel frame ,Shear (sheet metal) ,020303 mechanical engineering & transports ,low-yield-point steel (lyp) ,Bending moment ,business ,Geology - Abstract
This paper describes the seismic performance of a steel frame with additional LYP steel dampers. LYP steel dampers provides passive energy dissipation device in a structure, it also reduces the lateral forces in efficient way which is produced by seismic wave. The seismic performance of structures is needed in the design of structure, especially in countries where seismic activities occur. This analysis is accomplished with the FEM and software called SAP2000. The steel frame is only analyzed using numerical simulation. This paper describes two steel frames, the first steel frame is a two story steel frame without LYP steel dampers while the second steel frame has with LYP steel dampers. The seismic mechanism analysis was accomplished with the help of nonlinear time history analysis technique and the results for inter-story drift, steel frames, base shear, the displacement of the top story and the stress of the dampers was obtained. The time history analysis was taken out with three different earthquake waves according to the Chinese code for the seismic design of buildings; the earthquake waves were divided into the three different earthquake levels in China which include the frequent, moderate and rare earthquake level. The seismic mechanism analysis was accomplished on the three different earthquakes and three different earthquake levels in China. The modal analysis was taken to obtain the frequency and the period of the steel frames. The steel frames were examined under the different load combination which is also described in the code for the seismic design of buildings to obtain the internal forces of the members of the steel frame which include the axial force, shear force and bending moment. The different load combinations are used to get the stress of the dampers. We notice that the addition of LYP steel dampers increases the seismic resistance of the steel frame as we can observe by a reduction in the displacement of the top story, base shear, and inter-story drift angle by the addition of LYP steel dampers on the steel frame. We can be able to observe the behavior of the frames under the different earthquake levels in China using the pushover analysis.
- Published
- 2021
29. Improving the rotordynamic stability of short labyrinth seals using positive preswirl
- Author
-
Gu Qianlei, Wanfu Zhang, Wang Yingfei, Hao Cao, and Yin Lu
- Subjects
Materials science ,lcsh:Mechanical engineering and machinery ,System stability ,computational fluid dynamics ,02 engineering and technology ,Computational fluid dynamics ,Labyrinth seal ,01 natural sciences ,Stability (probability) ,Seal (mechanical) ,0203 mechanical engineering ,0103 physical sciences ,lcsh:TJ1-1570 ,General Materials Science ,010301 acoustics ,geography ,geography.geographical_feature_category ,business.industry ,preswirl ,Mechanical Engineering ,rotordynamic coefficient ,labyrinth seal ,Mechanics ,Inlet ,System characteristics ,020303 mechanical engineering & transports ,business - Abstract
Introducing a negative preswirl at the upstream of annular gas seals has been considered as an effective way to improve the system stability. This paper demonstrates a stability enhancement approach for a short labyrinth seal using positive preswirls. The static and dynamic characteristics of the labyrinth seal with various blade numbers (5, 10, 15), inlet preswirl ratios (–0.3, –0.15, 0, 0.15, 0.3) were studied. Results show that the inlet preswirl ratio has a dramatic effect on the circumferential location of the high-pressure spot for each seal cavity, particularly for the first cavity. The inlet preswirl ratio has opposite effects on the system stability due to the difference of high-pressure spot locations between the first cavity and the others. An increasing positive inlet preswirl could improve the system stability for the labyrinth seal with fewer blades (e.g. 5 blades). Its characteristics is mainly dominated by the first seal cavity. For the labyrinth seal with 10 blades, the system characteristics shows slight dependency on the inlet preswirl ratio. For the labyrinth seal with more blades (e.g. 15 blades), the negative inlet preswirl still increases the system stability, which agrees with the conventional conclusion. The paper provides a deeper understanding on the stability improvement of the labyrinth seal.
- Published
- 2020
30. The inner product vector as an output-only cross-correlation-based feature to structural damage assessment
- Author
-
Raimondo Betti and Marcello Morgantini
- Subjects
Computer science ,lcsh:Mechanical engineering and machinery ,Reliability (computer networking) ,02 engineering and technology ,computer.software_genre ,01 natural sciences ,inner product vector ,lanl 3-dof shear type ,0203 mechanical engineering ,0103 physical sciences ,structural local damage ,lcsh:TJ1-1570 ,General Materials Science ,010301 acoustics ,Structure (mathematical logic) ,structural health monitoring ,Cross-correlation ,Mechanical Engineering ,Response time ,cross-correlation ,020303 mechanical engineering & transports ,Feature (computer vision) ,Product (mathematics) ,output-only analysis ,Structural health monitoring ,Data mining ,Wireless sensor network ,computer - Abstract
This paper presents a structural damage assessment method that relies on a cross-correlation-based damage sensitive feature known as Inner Product Vector (IPV). Such a feature is extracted from the dynamic response measured at different locations within a structure. Previous investigations on the use of the IPV in a damage detection framework were conducted through laboratory tests by manipulating the excitation source in an input-output approach. In this paper, a new output-only approach has been developed to extract the Inner Product Vector only from the structural response time histories without knowledge of the input excitation. This is a more realistic scenario in structural health monitoring applications where it is difficult (in some cases, impossible) to monitor the external forces. The new estimation of the IPV is accomplished by taking the cross-correlations between filtered contributions to the overall structural response. It is shown how the elements of the IPV are affected by changes of the structural properties induced by damage and how effective the proposed approach is in the presence of external disturbances. The proposed approach has been proven to be very effective in dealing with dense sensor networks requiring large computational efforts. Numerical and experimental tests have been performed to address the reliability of the proposed damage index as a damage sensitive feature in an output-only framework.
- Published
- 2020
31. Influence of shield tunnel construction on ground surface settlement under the condition of upper-soft and lower-hard composite strata
- Author
-
Yong Tang, Xulong Li, Jianbing Lv, Hui Zhao, Zhanrong Li, and Helin Fu
- Subjects
Surface (mathematics) ,finite element simulation ,lcsh:Mechanical engineering and machinery ,Composite number ,02 engineering and technology ,01 natural sciences ,0203 mechanical engineering ,Shield ,0103 physical sciences ,Range (statistics) ,Groundwater-related subsidence ,ground surface settlement ,lcsh:TJ1-1570 ,General Materials Science ,Geotechnical engineering ,upper soft and lower hard composite stratum ,010301 acoustics ,Line (formation) ,Settlement (structural) ,Mechanical Engineering ,shield tunnel ,site monitoring ,020303 mechanical engineering & transports ,hard rock height ratio ,Geology ,Stratum - Abstract
Taking the shield tunnel project of Guangzhou Metro Line 8 from Tongdewei Station to Shangbu Station as the research background, using the research method of finite element simulation and site monitoring, this paper analyses the influence rules of shield tunneling on ground subsidence under the condition of different hard rock height ratios. The research results show that in the process of crossing different hard rock height ratio composite stratum, as the hard rock height ratio decreases, the value of ground settlement decreases and settlement tank becomes shallow. The surface subsidence in different hard rock height ratio strata is obviously different, and the maximum difference is about 8.6 mm; The influence of the hard rock height ratio on the surface longitudinal settlement is mainly reflected in the position change of the beginning and the end of the settlement. With the increase of the hard rock height ratio, the shield construction reduces the amount of the surface longitudinal settlement and its influence range; Through the research, it is found that the hard rock height ratio in the 0-0.2 and 0.5-1 is the sensitive interval, and the settlement value in these two hard rock height ratio interval varies greatly. It is necessary to pay attention to the uneven settlement of the ground surface caused by shield construction in the sensitive hard rock height ratio interval. The research results of this paper can provide reference value for similar shield construction in upper soft and lower hard composite stratum.
- Published
- 2020
32. An improved spectrum correlation time-frequency analysis method and its application in fault diagnosis of rolling element bearing
- Author
-
Hongchao Wang and Wenliao Du
- Subjects
Computer science ,spectrum correlation ,lcsh:Mechanical engineering and machinery ,Feature extraction ,02 engineering and technology ,Fault (power engineering) ,01 natural sciences ,law.invention ,0203 mechanical engineering ,Control theory ,law ,0103 physical sciences ,lcsh:TJ1-1570 ,General Materials Science ,rolling element bearing ,010301 acoustics ,Bearing (mechanical) ,improved spectrum correlation ,Noise (signal processing) ,Mechanical Engineering ,fault diagnosis ,Vibration ,020303 mechanical engineering & transports ,Rolling-element bearing ,integrated improved spectrum correlation ,Harmonic ,Frequency modulation - Abstract
The spectrum correlation (SC) is an effective fault feature extraction method for rolling bearing which is based on second order cyclic statistic. However, the effectiveness of SC will be compromised greatly when the rolling bearing fault feature signal is interfered by noise. To solve the problem, the SC method is improved and the improved spectrum correlation (ISC) method is proposed in the paper, and the noise-resistance virtue of ISC compared with SC is verified through the accelerated fatigue and compound fault test of rolling element bearing. Besides, the vibration signal of fault rolling bearing takes on modulation phenomenon, and extracting the fault characteristic frequency (FCF) or cyclic modulation frequency (CMF) is enough for the purpose of fault diagnosis, and the modulation frequency is neglected usually. However, the extraction result of ISC is not intuitive enough because it extracts the FCF and modulation frequency with its harmonic synchronously. To improve the intuitive feature extraction effect of ISC, the ISC method is improved further in the paper and the integrated improved spectrum correlation (IISC) is proposed which would only extract the FCF or CMF, so much clear and better extraction effectiveness could be obtained by IISC method, and the effectiveness and better fault extraction results by applying IISC method on vibration data of rolling bearing accelerated fatigue and compound fault test are also presented.
- Published
- 2020
33. Consideration of the problem about vibration of automobile in one fourth model with taking road deformation and the loss of contact into account
- Author
-
Dung Tran Quang, Ham Vu Cong, and Cuong Phung Manh
- Subjects
Partial differential equation ,Differential equation ,lcsh:Mechanical engineering and machinery ,Mechanical Engineering ,automobile ,Mathematical analysis ,Motion (geometry) ,02 engineering and technology ,Deformation (meteorology) ,01 natural sciences ,loss of contact ,Contact force ,Vibration ,020303 mechanical engineering & transports ,one-fourth model ,0203 mechanical engineering ,Ordinary differential equation ,0103 physical sciences ,lcsh:TJ1-1570 ,General Materials Science ,vibration ,Contact area ,road deformation ,010301 acoustics ,Mathematics - Abstract
This paper presents an approach to the problem about vibration of automobiles in one-fourth model where both road deformation and the loss of contact are taken into account. Contact characteristics such as the geometry of the contact area, pressure distribution, the relation between the contact force and the dimensions of the contact area, and therefore the change in dimensions of the contact area with respect to time are mentioned. Deformed road is modeled as an elastic beam which is simply supported at the two ends and lies on Kelvin’s visco-elastic ground. The differential equations of motion for both states of contact and losing contact are unified by introducing a so-called contact state parameter. The partial differential equation among the differential equations of motion of the vehicle-road coupled system is transformed into a system of all ordinary differential equations by applying the Bubnov-Galerkin’s method. A procedure for numerically solving the ordinary differential equations of motion of the vibration system under consideration is proposed and some numerical results for illustration are also presented in the paper.
- Published
- 2020
34. Dynamic response of auxetic structures
- Author
-
John Kennedy and Matthieu Proffit
- Subjects
Frequency response ,Materials science ,Auxetics ,business.industry ,Materials Science (miscellaneous) ,Structure (category theory) ,3D printing ,Metamaterial ,Mechanical engineering ,Industrial and Manufacturing Engineering ,Vibration ,Shock absorber ,Spring (device) ,Business and International Management ,business - Abstract
Auxetic materials have been investigated since the 1990’s, they are defined by a negative Poisson’s ratio which gives them interesting capabilities in energy and shock absorption. They are usually lattice structures (2D or 3D array of unit cells), which gives them high stiffness to weight properties and their properties can be tuned to suit a given application. Several papers have been published on new auxetic designs, their static equivalent mechanical properties, shock absorption properties and their manufacturing. Their dynamic behavior has not been studied to date and this is the main purpose of this paper. We will present a novel design that facilitates 3D printing with SLA printers and then examine the dynamic behavior of an auxetic structure between 0 and 1 kHz. In order to explain the unusual behavior of the structure, an initial theoretical model of non-linear spring has been developed with partial success.
- Published
- 2020
35. Phasor measuring unit calibration considering topology expansion of electric power utilities
- Author
-
Ganesan Sivarajan, Shanmugam Veeramuthu, and Subramanian Srikrishna
- Subjects
topology ,Computer science ,Mechanical Engineering ,Materials Science (miscellaneous) ,phasor measurement units (pmu) ,error biased ,Phasor ,Topology (electrical circuits) ,calibration ,Topology ,Network topology ,meta-heuristic ,Synchronization ,Electric power system ,Smart grid ,lcsh:Technology (General) ,lcsh:T1-995 ,Electric power ,Literature survey ,Instrumentation - Abstract
Phasor Measuring Units (PMU) is considered as a feasible alternative for power system data communication and for the preparation of smart grid. To operate multiple PMUs in stable mode, synchronization is a much essential procedure. After examining the concise literature survey on topical PMU applications, this paper step ahead by considering prevailing objectives such as: extension of network topology and PMU calibration considering bias errors. The appropriate deployment of PMUs and intimidating situation influence the reliance on physical configuration. Hence, it is obligatory to extend the topology of the networks. Also, calibrating the PMUs in a definite trail is crucial as the phasor measurements will be corrupted by bias error. This paper proposes a novel framework for bias error detection and calibration of PMU while expanding the topology network. With a whale optimization algorithm based method to improve the accuracy of PMU measurements for enhancing power system state estimation, monitoring and control operations. Case studies on the standard test systems have been conducted to test the efficacy of the intended tool.
- Published
- 2020
36. Coupling characteristic analysis of ship shafting design parameters and research on multidisciplinary design optimization
- Author
-
Fanming Zeng, Jinlin Liu, and Yin Hongsheng
- Subjects
Computer science ,lcsh:Mechanical engineering and machinery ,02 engineering and technology ,01 natural sciences ,0203 mechanical engineering ,Multidisciplinary approach ,0103 physical sciences ,medicine ,lcsh:TJ1-1570 ,General Materials Science ,Radial basis function ,010301 acoustics ,ComputingMethodologies_COMPUTERGRAPHICS ,whirling vibration ,Artificial neural network ,Mechanical Engineering ,Multidisciplinary design optimization ,ship shafting ,Stiffness ,Control engineering ,multidisciplinary design optimization ,shafting alignment ,Vibration ,020303 mechanical engineering & transports ,medicine.symptom ,Engineering design process ,Decoupling (electronics) - Abstract
In the design process of traditional ship shafting, the design quality is generally hard to get guaranteed for the lack of discipline coupling. In this paper, Multidisciplinary Design Optimization (MDO) is innovatively introduced to ensure design quality. Multidisciplinary decomposition of shafting can help to construct the MDO model of ship shafting based on multidisciplinary feasibility method. Then the sub-discipline model of shifting design can be further established, including calibration neutron discipline model, whirling vibration model, and dynamic stiffness of radial oil film bearing model. Collaborative operation is implemented by the multidisciplinary model of shifting to obtain the experimental results. Based on Radial Basis Function (RBF) neural network, the responsive surfaces of variable, bearing load, and support stiffness can be constructed, in the meanwhile the dynamic stiffness decoupling of vibration model can be obtained. Fireworks algorithm is used to establish multidisciplinary optimization of seven-dimensional design variable. The results show that MDO helps improve the quality of shafting alignment and whirling vibration. The work in present paper also provides insight for the future optimization of research methods, design quality, and engineering experiments.
- Published
- 2020
37. Dynamic simulation analysis of spur gear space driven system with large inertia load
- Author
-
Hongbin Yang, Xuehao Yin, Jianfeng Ma, and Chao Li
- Subjects
Computer science ,lcsh:Mechanical engineering and machinery ,media_common.quotation_subject ,MathematicsofComputing_NUMERICALANALYSIS ,02 engineering and technology ,Inertia ,01 natural sciences ,large inertia load ,0203 mechanical engineering ,Control theory ,0103 physical sciences ,medicine ,lcsh:TJ1-1570 ,General Materials Science ,backlash ,010301 acoustics ,dynamic response ,media_common ,Noise (signal processing) ,spur gear ,Mechanical Engineering ,Stiffness ,adams ,Vibration ,Mechanism (engineering) ,Dynamic simulation ,Nonlinear system ,020303 mechanical engineering & transports ,medicine.symptom ,Backlash - Abstract
The wide application of large inertia loads in space drive mechanisms is relatively rare in theoretical research. An 8-degree-of-freedom nonlinear dynamic model is established for the time-varying and nonlinear perturbation problems of a large inertia load space drive mechanism. The model is a two-stage spur gear model in which the effects of backlash and time-varying stiffness are considered. The 3D model was imported into ADAMS, and the nonlinear dynamic response of the system was studied by motion simulation. This paper sets up a large inertia experimental device to collect and process data. Comparing experimental results with Adams results, the correctness of the numerical model was verified, and the reasons for the differences between the two were explained. A comparative analysis of the load response under different inertia was performed to illustrate the importance of studying large inertia loads. The simulation results show that the output shaft has a great influence on the dynamic response. Changing the material of the gear can improve the transmission precision of the gear system. The analysis results in this paper enrich the research on the dynamic response of gear system, and provide a theoretical basis for the subsequent design of large inertia load gear system and improve vibration and noise during operation.
- Published
- 2020
38. DEM simulation and experimental study on the screening process of elliptical vibration mechanical systems
- Author
-
Lijie Zhang, Jiwei Yan, Bing Chen, Mo Wei, Chuanlei Xu, and Kumar K. Tamma
- Subjects
Screening test ,Computer science ,lcsh:Mechanical engineering and machinery ,Mechanical Engineering ,Process (computing) ,Mechanical engineering ,02 engineering and technology ,Simulation system ,simulation ,01 natural sciences ,Discrete element method ,screening experiment ,Mechanical system ,Mechanism (engineering) ,Vibration ,020303 mechanical engineering & transports ,0203 mechanical engineering ,0103 physical sciences ,elliptical vibration system ,lcsh:TJ1-1570 ,General Materials Science ,discrete element method ,010301 acoustics ,Throughput (business) - Abstract
For an elliptical vibration system, the vibration parameters seriously affect conveying speed and sieving efficiency of the materials. In addition, considering the lack of studies about the elliptical vibration machine, we applied the discrete element method to simulate and analyze the elliptical vibration screening process in this paper. A vibration screening model is particularly based on the purpose of our research to fundamentally demonstrate the novel relationships among the conveying speed, sieving efficiency and vibration parameters of the materials. And the sieving experiment of typical materials is additionally carried out on the same simulation system. This paper analyzes the influence rule of vibration parameters on conveying speed and sieving efficiency of the materials during the elliptical vibration screening process by virtue of comprehensively comparing the results of experimental study coupled with simulation research. Consequently, we can throw up the optimal vibration screening parameters to guarantee high sieving efficiency and large throughput of the screening machine at the same time. The screening test carried out in this paper lays the experimental foundation for the study of the mechanism of elliptical vibration screening machine and the study of materials screening characteristics by combining the conclusions of DEM simulation analysis of lots of materials. It provides not only a basis for selecting the vibration parameters of the actual working process of the screening machine, but also data support based on the experiment and simulation for the study of the sieving mechanism of elliptical vibration systems. For screening mechanism, this is a significant progress which will affect future design and manufacture of elliptical vibration machines. Furthermore, the conclusions drawn from this research can help us study and explain better the screening process of other vibration machinery.
- Published
- 2019
39. Multi-body dynamic simulation and vibration transmission characteristics of dual-rotor system for aeroengine with rubbing coupling faults
- Author
-
Jingyu Zhai, Qingkai Han, Pingping Ma, and Hao Zhang
- Subjects
Computer science ,lcsh:Mechanical engineering and machinery ,02 engineering and technology ,Fault (power engineering) ,01 natural sciences ,law.invention ,Physics::Popular Physics ,0203 mechanical engineering ,law ,0103 physical sciences ,lcsh:TJ1-1570 ,General Materials Science ,010301 acoustics ,rub-impact ,Coupling ,vibration coupling and transfer ,business.industry ,Rotor (electric) ,aero-engine dual-rotor system ,Mechanical Engineering ,Structural engineering ,Rubbing ,Dynamic simulation ,Vibration ,020303 mechanical engineering & transports ,multi-body dynamics model ,Helicopter rotor ,business ,Casing - Abstract
In this paper, a dual-rotor system multi-body dynamic model with rubbing coupling faults is established for practical aero-engine. In the model, the rubbing fault simulation method is introduced, the coupling effect between the internal and external rotor is considered. The numerical simulations of rotor vibration are accomplished by the utilization of multi-body dynamic platform, where the simulation model consists of discs unbalances and local rub-impact between discs and casing shells. The time-domain responses, the frequency spectra and the shaft-center trajectories of dual-rotor with different unbalance and different rubbing positions are obtained. The vibration and its transmission characteristics of the inner and outer rotors are calculated. Finally, the simulation results are compared with the measured vibration of a dual rotor tester with rubbing fault. The simulation results are consistent with the measured results, which confirms the feasibility of the established model and the multi-body dynamics simulation method in this paper. The application of multi-body dynamics simulation method in aero-engine can deepen the understanding of the internal operation nature and laws of aero-engine, reduce the repetition of physical tests, greatly improve the efficiency and quality of development, accelerate the research and manufacture process.
- Published
- 2019
40. Pressure ripple of gear pumps affected by air content on trapped volume.
- Author
-
Xiaoru Hao, Xiaojun Zhou, Xiaoguang Liu, and Xiaohu Sang
- Subjects
- *
VIBRATION (Mechanics) , *COMPUTATIONAL fluid dynamics , *GEAR pumps , *AIR pressure , *MECHANICAL engineering - Abstract
A general assumption about fluid power systems is that the pressure ripple of trapped volume is a primary source for fluid-borne noise. Whereas the high frequency vibration characteristics generated by pressure fluctuations of trapped volume are different under different air content in the oil. This paper presents the non-Newtonian fluid models to describe the oil flow condition in external gear pumps. In this analysis, pressure ripple due to compressibility of fluid is considered, and the effect of pressure ripple in the trapped volume of external gear pumps has been investigated by comparing with 8 % air content and 10 % air content in the oil. It was found that the amplitude of pressure fluctuation would drop about 2.5 MPa with the increase 2 % of the air content under the same conditions of load and speed. The whole work was performed on the computational fluid dynamics (CFD) environment, an efficient tool for the simulation of dynamic engineering systems, and more particularly of fluid power. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
41. Modal identification of Karun IV arch dam based on ambient vibration tests and seismic responses.
- Author
-
Tarinejad, R., Falsafian, K., Aalami, M. T., and Ahmadi, M. T.
- Subjects
- *
EFFECT of earthquakes on arch dams , *VIBRATION (Mechanics) , *SEISMIC response , *CONCRETE construction , *MECHANICAL engineering - Abstract
This paper focuses on the operational modal analysis of the Karun IV dam, the highest concrete arch dam in Iran, based on the responses obtained from ambient vibration tests, which are carried out on the dam during 19 March 2014, and 3 March 2015 earthquake with an epicenter about 133 km northeast of the dam. The non-parametric FDD-Wavelet method is used for identification and extraction of modal parameters including natural frequencies, mode shapes and damping ratios. Nine and four natural frequencies are identified from ambient and seismic responses, respectively. Stabilization diagram and averaged coherence spectrum (ACS) are used to detect and eliminate spurious form true modes. Comparison of the results indicates that identification is performed properly and reliably. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
42. Investigation on chatter stability of thin-walled parts in high-speed milling based on relative transfer functions.
- Author
-
Lida Zhu, Yang Ding, Changfu Liu, and Zhiwei Xu
- Subjects
- *
MILLING (Metalwork) , *DEGREES of freedom , *MECHANICAL engineering , *TRANSFER functions , *SYSTEMS design - Abstract
High-speed milling of thin-walled part is a common application for aerospace industry, automotive, computer hardware and bioengineering industries. Aiming at the small-stiffness frequency response characteristics of thin-walled parts, the dynamic model and critical condition of stability was proposed by the relative transfer functions between cutter subsystem and thin-walled part subsystem in this paper. The stability critical domain was predicted by semi-discretization (SD) method based on the dynamic behavior of the multi-DOF system. It can be shown that the chatter condition in high-speed milling is closely related to both cutter speed and depth of cut, besides cutter geometry, engagement conditions, relative frequency response function, material property of thin-walled part and so on. This conclusion provides a theoretical foundation and reference for the milling mechanism research. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
43. 1890. Adaptive multi-grid FE simulation on dynamic damage and seismic failure of concrete structures.
- Author
-
Bin Sun and Zhaoxia Li
- Subjects
- *
SIMULATION methods & models , *CONCRETE analysis , *SEISMIC waves , *VIBRATION (Mechanics) , *MECHANICAL engineering - Abstract
This paper presents a new adaptive multi-grid method for analyses on damage and failure in concrete column under cyclic loading. Self-adaptation of the method can carry out automatically coupling analysis on the process of evolving damage to structural failure with dynamic grid-change due to damage, without user intervention in the computation. The theory of multi-grid FEM coupled evolving damage is developed on the basis of the improved variational principle to consider damage evolution, in which the elements in each sub-domain with different grid sizes are under the different state of damage. Then the multi-grid FEM method is provided with the theory and a 3D adaptive mesh refinement procedure. As a case study of the method, the process of evolving damage to failure of a concrete column under cyclic loading is simulated by using the developed method, and the simulated results fit well with the experimental data. The results show that, the developed method is reliable in simulation on evolving damage and failure in concrete column under dynamic seismic loading with lower cost and sufficient precision. [ABSTRACT FROM AUTHOR]
- Published
- 2016
44. 1834. An on-line diagnostics application for evaluation of machine vibration based on standard ISO 10816-1.
- Author
-
Listewnik, Karol, Grzeczka, Grzegorz, Kłaczyński, Maciej, and Cioch, Witold
- Subjects
- *
VIBRATION (Mechanics) , *SERVICE life , *PULSATION (Electronics) , *PARAMETER estimation , *MECHANICAL engineering - Abstract
Machines that generate vibroacoustic processes are tested at every stage of their life cycle. Since the greatest changes in the level of machines' pulsation are occurring during the exploitation, vibration parameters are often used to evaluate their operation. Many years of research, whose results and conclusions are contained in the standards give a good methodological tool to assess the state of machines. The most commonly used standard is ISO 10816-1. Mechanical vibration. Evaluation of mechanical vibration by measurements on non-rotating parts - Part 1: General guidelines. On the other hand, the standard itself is not enough, the current monitoring parameters contained in the standard requires to hold or construction of easily configurable system for measuring, analyzing and archiving. This paper describes the work includes the methods of the measurement, the concepts of the measurement system and the method of the calculation, algorithm and software applications named VibroTest, created in National Instrument Lab VIEW Environment. This authors system allows assessment of the machine under test, based on the signals generated by the tested machine. [ABSTRACT FROM AUTHOR]
- Published
- 2015
45. Influence of location of measurement point on evaluation of human perception of vibration
- Author
-
Alicja Kowalska-Koczwara
- Subjects
Measurement point ,vibrational comfort ,Computer science ,Mechanical Engineering ,Materials Science (miscellaneous) ,media_common.quotation_subject ,Acoustics ,in-situ measurement ,RMS ,Vibration ,Vibration perception ,Perception ,lcsh:Technology (General) ,Evaluation methods ,lcsh:T1-995 ,Quality (business) ,measurement point location ,human perception of vibration ,Instrumentation ,media_common - Abstract
Human perception of vibration is very subjective parameter which depends among others on age, sex or even nationality. There are three main methods of assessment of human perception of vibration according to national standards which differ from each other. All three methods are clearly described in this paper and their advantages and disadvantages are shown. Evaluation methods are helpful in diagnosis and design of the building when they are used properly. One of interesting aspect of quality of measurements is localization of measurement points. The choice of localization of measurement points could have significant influence on result of evaluation of human response to vibration. International and national standards are compatible in this matter – measurement points should be localized in the place of human vibration perception. It means that should be located in the middle of the floor. Sometimes it is difficult to determine the exact center of the floor, especially when building has irregular construction. In this paper influence of localization of measurement point on human perception of vibration is investigated and center zone in which measurement results are proper is determined. In-situ measurements were made to investigate the problem of localization of human vibration perception in buildings.
- Published
- 2019
46. Bearing degradation assessment based on entropy with time parameter and fuzzy c-means clustering
- Author
-
Xin Zhang, Haiping Li, Guozeng Liu, and Jianmin Zhao
- Subjects
Computer science ,lcsh:Mechanical engineering and machinery ,time parameter ,02 engineering and technology ,01 natural sciences ,Fuzzy logic ,law.invention ,Wavelet packet decomposition ,0203 mechanical engineering ,Control theory ,law ,0103 physical sciences ,Entropy (information theory) ,lcsh:TJ1-1570 ,General Materials Science ,Degradation process ,Cluster analysis ,010301 acoustics ,Bearing (mechanical) ,Time parameter ,Mechanical Engineering ,bearing degradation assessment ,020303 mechanical engineering & transports ,Intelligent maintenance system ,entropy ,clustering - Abstract
Bearings are one of the most crucial elements in rotating machine. The condition of bearings decides the operation of machine. Consequently, it is necessary to study the assessment of bearing degradation in order to develop condition-based maintenance. This paper improves an indicator based on entropy which is calculated by wavelet packet decomposition and auto-regressive model. By introducing time parameter, the indicator solves the problem of instability in the initial stage of operation and it is less influenced by the operational conditions. Then, fuzzy c-means clustering can evaluate the process of degradation. Moreover, it can provide the threshold adaptively and help to repair by unit replacement. To ensure the applicability, the data of this paper comes from two laboratories, FEMTO-ST Institute and Intelligent Maintenance System Center. The result indicates that the method is effective to assess bearing degradation process.
- Published
- 2019
47. Hybrid spectral speed determination method for rotary machines
- Author
-
Gabor Gardonyi and Krisztián Samu
- Subjects
cepstrum ,Computer science ,lcsh:Mechanical engineering and machinery ,diagnostic ,02 engineering and technology ,01 natural sciences ,spectrum ,Cylinder (engine) ,law.invention ,rotary machine ,0203 mechanical engineering ,law ,Control theory ,0103 physical sciences ,Spark (mathematics) ,Cepstrum ,hybrid method ,lcsh:TJ1-1570 ,General Materials Science ,010301 acoustics ,Measure (data warehouse) ,Mechanical Engineering ,Rotational speed ,rotational speed ,Vibration ,020303 mechanical engineering & transports ,Train ,State (computer science) - Abstract
Accurate rotational speed determination for rotary machines tends to be allocated high priority in technical applications. In some cases, it is not easy to measure shaft speed directly. Vibration diagnostic tools can offer an alternative solution to the problem posed by direct rotational speed measurement. Using calculated spectra and cepstra can help to determine the rotational speed easily and accurately. This paper examines the comparison of the spectrum and cepstrum based methods in terms of their applicable ranges and rotational speed estimation accuracy. Most papers which present similar comparisons state that the speed of rotary machines can be determined better with cepstrum calculation. However, this argument does not entirely stand up to scrutiny. This paper explains how to calculate the possible speed estimation error which arises out of the resolution of the discrete output data produced by the methodologies. The novel hybrid speed estimation logic uses these equations to decide which method results in the most accurate output. Numerous vibration measurements were made to test the usability of this hybrid method. It was successfully tested on electromotive drive trains, as well as spark- and compression-ignition internal combustion engines with different cylinder numbers and arrangements.
- Published
- 2019
48. Analysis of acoustic insulation in traditional wooden architecture hotel building
- Author
-
Bartłomiej Ziarko, Krzysztof Nering, and Krzysztof Stypuła
- Subjects
Engineering ,business.industry ,Mechanical Engineering ,Materials Science (miscellaneous) ,Mineral wool ,traditional wooden architecture ,Ceiling (cloud) ,Reinforced concrete ,Civil engineering ,sound insulation ,Soundproofing ,lcsh:Technology (General) ,lcsh:T1-995 ,Architecture ,business ,Instrumentation ,Acoustic insulation ,vibroacoustical comfort - Abstract
This paper presents evaluation of vibroacoustical requirements in the context of impact and airborne sound insulation in hotel building. This building represents traditional wooden architecture present in southern Poland. Similar structures can be found all around Europe in mountainous areas. Due to fact that there are little information about acoustic conditions of such buildings, this paper gives measured values of sound insulation of typical solutions used in this architecture. In order to define if requirements of current polish standard PN-B-02151-03:2015 for hotel buildings are met, impact sound level and airborne sound insulation of representative partitions were measured. Measurement conducted in presented building shows issues connected with non-sufficient airborne sound insulation of internal partitions – timber log walls. Due to its low mass and, in simplification, homogenous structure, its sound insulation is far from meeting requirements. Considering timber structural ceiling and reinforced concrete floor present in hotel building requirements of impact sound level and airborne sound insulation are met. The solution of weak acoustic conditions of walls is proposed as plasterboard pre-wall with mineral wool inside.
- Published
- 2019
49. Performance optimization of banana vibrating screens based on PSO-SVR under DEM simulations
- Author
-
Xin Tong, Zhanfu Li, Li Kunyuan, and Xiaole Ge
- Subjects
LS-SVM ,Computer simulation ,Computer science ,lcsh:Mechanical engineering and machinery ,Mechanical Engineering ,ASFA ,DEM ,banana screen ,Particle swarm optimization ,Small sample ,Vibration ,Support vector machine ,screening performance ,Kernel (image processing) ,Control theory ,Robustness (computer science) ,lcsh:TJ1-1570 ,General Materials Science ,Statistical theory ,optimization - Abstract
This paper carried out the numerical simulation about the movement of non-spherical particles on banana vibrating screen using direct element method (DEM) considering the complexity of particle collision and avoiding obtaining motion information with difficulty. Experimental prototype of banana vibrating screen under variable parameters was manufactured to verify the feasibility of simulations. Because the complex non-linear mathematical model is the basis of optimization. Based on the simulation data this paper applied the least squares support vector machines (LS-SVM) to establish relationships between vibrating parameters of banana screen and screening performance. LS-SVM based on statistical theory can effectively solve the mapping problem of small sample. At same time, in order to improving the quality of modeling, the kernel parameters of SVM were optimized by particle swarm optimization (PSO). Considering multi-extremum, large-scale, and non-differentiable of this computational model, the artificial fish-swarm algorithm (AFSA) with strong robustness and global convergence was applied to vibration parameters optimization. Finally, the optimal vibration parameters were: vibration amplitude 2.4 mm, vibration frequency 21 Hz, vibration direction angle 40 degrees.
- Published
- 2019
50. Analysis of vibration propagation in the human body
- Author
-
Rafał Burdzik
- Subjects
vibration propagation ,Computer science ,Oscillation ,Mechanical Engineering ,Materials Science (miscellaneous) ,Acoustics ,Human body ,human vibration ,Signal ,sitting position ,Vibration ,lcsh:Technology (General) ,lcsh:T1-995 ,Head (vessel) ,Instrumentation ,Transport system - Abstract
The human vibration is a multi-disciplinary subject involving many disciplines. A special area in the field of vibration research is the transport system. The paper presents the results of preliminary tests, the aim of which was to analyze the propagation of vibrations forced by the movement of the vehicle floor on persons sitting in a car. During research vibration were registered in measurement nodes, in which the composition always included the signal of oscillation of the enforcing plate and specific locations on the human body. This paper presents results of vibration recorded on the extinction plate and on the head of the passenger.
- Published
- 2018
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