Fault Detection of Gears With Different Root Crack Size Using Wavelet

2015 ◽  
Author(s):  
Xinpeng Hu ◽  
Xi Wu ◽  
Jixin Wang ◽  
Jim Meagher
Keyword(s):  
Vibration Signal ◽  
Crack Size ◽  
Gear System ◽  
Time Varying ◽  
Hertz Contact ◽  
Transient Vibration ◽  
Gear Teeth ◽  
Meshing Stiffness ◽  
Vibration Signatures ◽  
Root Crack

Although tremendous effort has been applied to develop reliable strategies for detecting tooth cracks of gearboxes, these methods have generally fallen short of the required performance. Cracks are usually initiated at the root of a tooth and are very difficult to be identified from time-domain measurement. The vibration signal transformed by wavelet is sensitive to energy change. In this study, the transient vibration variations induced by different sizes of cracks at the tooth root are captured using wavelet. Firstly, as the main parametric excitation, the time-varying gear meshing stiffness caused by the alternating of engaged gear teeth is accurately calculated based on energy method, in which comprehensive deformations including Hertz contact, axial compression, bending, shearing and fillet-foundation deflection are taken into consideration. Moreover, a sophisticated dynamic theoretical model is used to simulate a practical gear system. Unique vibration signatures are captured through the comparison of cracked and perfect gear system.

scholarly journals Frequency and Vibration Characteristics of High-Speed Gear-Rotor-Bearing System with Tooth Root Crack considering Compound Dynamic Backlash

2019 ◽  
Vol 2019 ◽  
pp. 1-19 ◽  
Author(s):  
Jie Liu ◽  
Weiqiang Zhao ◽  
Weiwei Liu
Keyword(s):  
Time Domain ◽  
Crack Depth ◽  
Transmission System ◽  
Gear System ◽  
Time Varying ◽  
Tooth Root ◽  
Meshing Stiffness ◽  
The Time Domain ◽  
Center Distance ◽  
Root Crack

Considering the microstructure of tooth surface and the dynamic characteristics of the vibration responses, a compound dynamic backlash model is employed for the gear transmission system. Based on the fractal theory and dynamic center distance, respectively, the dynamic backlash is presented, and the potential energy method is applied to compute the time-varying meshing stiffness, including the healthy gear system and the crack fault gear system. Then, a 16-DOF coupled lateral-torsional gear-rotor-bearing transmission system with the crack fault is established. The fault characteristics in the time-domain waveform and frequency response and statistics data are described. The effect of crack on the time-varying meshing stiffness is analyzed. The vibration response of three backlash models is compared. The dynamic response of the system is explored with the increase in crack depth in detail. The results show that the fault features of countershaft are more obvious. Obvious fluctuations are presented in the time-domain waveform, and sidebands can be found in the frequency domain responses when the tooth root crack appears. The effect of compound dynamic backlash on the system is more obvious than fixed backlash and backlash with changing center distance. The vibration displacement along meshing direction and dynamic meshing force increases with the increase in crack depth. Backlash and variation of center distance show different tendencies with increasing crack depth under different rotational speeds. Amplitude of the sidebands increases with crack depth increasing. The amplitude of multiplication frequency of rotational frequency has an obvious variation with growing crack depth. The sidebands of the multiplication frequency of meshing frequency show more details on the system with complex backlash and crack fault.

Research on dynamic characteristics of gear system considering the influence of temperature on material performance

2021 ◽  
pp. 107754632110026
Author(s):  
Zhou Sun ◽  
Siyu Chen ◽  
Xuan Tao ◽  
Zehua Hu
Keyword(s):  
Elastic Modulus ◽  
Dynamic Characteristics ◽  
Poisson’S Ratio ◽  
Gear System ◽  
Poisson's Ratio ◽  
Effect Of Temperature ◽  
Time Varying ◽  
Influence Of Temperature ◽  
Meshing Stiffness ◽  
Influence Of Temperature On

Under high-speed and heavy-load conditions, the influence of temperature on the gear system is extremely important. Basically, the current work on the effect of temperature mostly considers the flash temperature or the overall temperature field to cause expansion at the meshing point and then affects nonlinear factors such as time-varying meshing stiffness, which lead to the deterioration of the dynamic transmission. This work considers the effect of temperature on the material’s elastic modulus and Poisson’s ratio and relates the temperature to the time-varying meshing stiffness. The effects of temperature on the elastic modulus and Poisson’s ratio are expressed as functions and brought into the improved energy method stiffness calculation formula. Then, the dynamic characteristics of the gear system are analyzed. With the bifurcation diagram, phase, Poincaré, and fast Fourier transform plots of the gear system, the influence of temperature on the nonlinear dynamics of the gear system is discussed. The numerical analysis results show that as the temperature increases, the dynamic response of the system in the middle-speed region gradually changes from periodic motion to chaos.

Analysis of tooth stiffness of nutation face gear

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Guangxin Wang ◽  
Lili Zhu ◽  
Peng Wang
Keyword(s):  
Gear Transmission ◽  
Time Varying ◽  
Mesh Stiffness ◽  
Face Gear ◽  
Content Type ◽  
Gear Teeth ◽  
Meshing Stiffness ◽  
Single Tooth ◽  
Tooth Stiffness ◽  
External Face

Purpose The purpose of this paper is to obtain the single-tooth stiffness, single-tooth time-varying meshing stiffness and comprehensive meshing stiffness of the internal and external face gears and to analyze the influence of the modulus, pressure angle and tooth width of each face gear on the single-tooth stiffness of the gear in nutation face gear transmission. Design/methodology/approach From the point of view of material mechanics, the gear teeth of nutation face gear are simplified as spacial variable cross-section beams. The shear deformation of gear teeth, the bending deformation of tooth root and the additional elastic deformation caused by the base deformation are gotten by simplified trapezoidal section method, thus the stiffness of nutation face gear teeth can be obtained. The comparison with finite element method results verifies the rationality of simplified trapezoidal section method for calculating the tooth stiffness of nutation face gear. Findings The variation of stiffness of internal and external face gears along the meshing line and tooth height in nutation face gear transmission is studied, and the variation laws of single tooth stiffness, single-tooth-pair mesh stiffness and single tooth time-varying meshing stiffness of nutation face gear teeth are obtained. Originality/value Nutation face gear transmission is a new type of transmission. The stiffness of face gear teeth is analyzed, and the variation rules of single tooth stiffness, single-tooth-pair mesh stiffness and single tooth time-varying meshing stiffness of nutation face gear teeth are obtained, which not only enriches the research of nutation face gear transmission but also has important guiding significance for the application of nutation face gear in engineering practice.

Features of Early Cracks in a Gear Based on a 16DOF Nonlinear Time-Varying Stiffness Dynamic Model

2009 ◽  
Author(s):  
Xiaojun Zhou ◽  
Yimin Shao ◽  
Ming J. Zuo
Keyword(s):  
Crack Growth ◽  
Dynamic Model ◽  
Digital Filter ◽  
Energy Method ◽  
Vibration Signal ◽  
Spur Gear ◽  
Time Varying ◽  
Meshing Stiffness ◽  
One Stage ◽  
The Relationship

A 16DOF nonlinear time-varying stiffness dynamic model of a one-stage spur gear system is studied when there is a crack growth on the pinion; the energy method is then used for calculating the meshing stiffness of the gear pairs. A Hybrid Digital Filter is used to detect the feature signal which is induced by the tooth crack when the vibration signal contains heavy noise. The relationship between the indicators and the growth of the crack is given.

scholarly journals Nonlinear characteristics of a multi-degree-of-freedom wind turbine’s gear transmission system involving friction

2021 ◽  
Author(s):  
Qiang Zhang ◽  
Xiaosun Wang ◽  
Shaobo Cheng ◽  
Fuqi Xie ◽  
Shijing Wu
Keyword(s):  
Excitation Frequency ◽  
Transmission System ◽  
Friction Model ◽  
Gear Transmission ◽  
Degree Of Freedom ◽  
Gear System ◽  
Time Varying ◽  
High Frequency Region ◽  
Meshing Stiffness ◽  
Gear Transmission System

Abstract In this study, a 42-degree-of-freedom (42-DOF) translation-torsion coupling dynamics model of the wind turbine’s compound gear transmission system considering time-varying meshing friction, timevarying meshing stiffness, meshing damping, meshing error and backlash is proposed. Considering the different meshing between internal and external teeth of planetary gear, the time-varying meshing stiffness is calculated by using the cantilever beam theory. An improved mesh friction model takes account into the mixing of elastohydrodynamic lubrication (EHL) and boundary lubrication to calculate the time-varying mesh friction. The bifurcation diagram is used to analyze the bifurcation and chaos characteristics of the system under the excitation frequency as bifurcation parameter. Meanwhile, the dynamic characteristics of the gear system are identified from the time domain diagrams, phase diagrams, Poincare maps and amplitude-frequency spectrums of the gear system. The results show that the system has complex bifurcation and chaotic behaviors including periodic, quasi-periodic, chaotic motion. The bifurcation characteristics of the system become complicated and the chaotic region increases considering the effects of friction in the high frequency region.

Nonlinear dynamic analysis of gear system in shearer cutting section under wear failure

2021 ◽  
pp. 146441932110535
Author(s):  
Lianchao Sheng ◽  
Wei Li ◽  
Guo Ye ◽  
Ke Feng
Keyword(s):  
Nonlinear Dynamic Analysis ◽  
Transmission Error ◽  
Gear System ◽  
Radial Clearance ◽  
Gear Teeth ◽  
Meshing Stiffness ◽  
Vibration Impact ◽  
Coupling Factors ◽  
Dynamic Meshing ◽  
Internal Error

Gear wear failure is one of the important failures of the gear system in the shearer cutting section. To reveal the influence mechanism of shearer cutting gear wear on the system dynamic characteristics, considering coupling factors such as time-varying meshing stiffness, dynamic gear clearance, internal error excitation, end load constraint and bearing radial clearance under wear failure, an improved dynamic model of shearer drive gear system is introduced to present an in-depth investigation of uniform wear of gear teeth effect. The dynamic meshing stiffness of gears under different degrees of wear is analysed. Furthermore, the bifurcation diagram is utilized to observe the motion state of the system experiencing different excitation frequencies, support damping as well as terminal loads. It is demonstrated that the gear surface wear could bring a change in gear dynamic transmission error, vibration impact state and amplitude, which is mainly manifested in increasing the unstable area and the vibration amplitude of the gear system, providing a method for monitoring and diagnosing of gear surface faults.

Bending-torsional-axial-pendular nonlinear dynamic modeling and frequency response analysis of a marine double-helical gear drive system considering backlash

2021 ◽  
pp. 146134842110657
Author(s):  
Hao Dong ◽  
Yue Bi ◽  
bo Wen ◽  
Zhen-bin Liu ◽  
Li-bang Wang
Keyword(s):  
Frequency Response ◽  
Dynamic Modeling ◽  
External Load ◽  
Transmission Error ◽  
Helical Gear ◽  
Gear System ◽  
Time Varying ◽  
Vibration Displacement ◽  
Meshing Stiffness ◽  
Nonlinear Dynamic Modeling

The double-helical gear system was widely used in ship transmission. In order to study the influence of backlash on the nonlinear frequency response characteristics of marine double-helical gear system, according to the structural characteristics of double-helical gear transmission, considering the time-varying meshing stiffness, backlash, damping, comprehensive transmission error, external load excitation, and other factors, a three-dimensional bending-torsional-axial-pendular coupling nonlinear dynamic modeling and dynamic differential equation of 24-DOF double-helical gear transmission system were established. The Runge–Kutta numerical method was used to analyze the influence of backlash, time-varying meshing stiffness, damping, error and external load excitation on the amplitude frequency characteristics. The results show that the backlash can cause the runout of the double-helical gear system, and the system has first harmonic and second harmonic response. With the increase of backlash, the amplitude of the system increases and the jumping phenomenon remains unchanged. The amplitude frequency response of the system is stimulated by time-varying meshing stiffness and comprehensive transmission error, and restrained by damping and external load excitation. The vibration displacement amplitude of the system increases with the increase of vibration displacement and has little effect on the state change of the system. The vibration test of double-helical gear is carried out. The frequency response components obtained by numerical simulation are basically consistent with the experimental results, which proves the correctness of the theoretical calculation. It provides a technical basis for the study of vibration and noise reduction performance of double-helical gear.

Dynamic Simulation of 2K-H Differential Gear Train with Time-Varying Meshing Stiffness

2011 ◽  
Vol 314-316 ◽  
pp. 1603-1606
Author(s):  
Ying Chen Ma ◽  
Yan Wang ◽  
Ji Sheng Ma ◽  
Hai Ping Liu
Keyword(s):  
Life Prediction ◽  
Theoretical Data ◽  
Gear System ◽  
Gear Train ◽  
Time Varying ◽  
Meshing Stiffness ◽  
Torsion Vibration ◽  
Differential Gear ◽  
Gear Contact ◽  
Object Dynamic

Taking 2K-H differential gear train as study object, dynamic equation of torsion vibration was established with influence of time-varying meshing stiffness. The virtual-prototype with nonlinear meshing force was modeled using Virtual.Lab Motion software. Gear contact force was simulated, and it was verified by theoretical data. The reason of meshing vibration is analyzed. The results show that time-varying meshing stiffness is the main excitation of gear system, and gear system is vibratory although the input and output are stable, and the basic frequency is meshing frequency. This research lays foundation for strength checking, optimum design and fatigue life prediction.

Dynamic Analysis of a Multi-Mesh Gear System With Mesh Stiffness Variation

2013 ◽  
Author(s):  
Hanjun Jiang ◽  
Yimin Shao
Keyword(s):  
Numerical Simulation ◽  
Dynamic Analysis ◽  
Degrees Of Freedom ◽  
Gear System ◽  
Time Varying ◽  
Mesh Stiffness ◽  
Gear Teeth ◽  
Linear Dynamic ◽  
Complex Oscillation ◽  
Stiffness Variation

Parameter excited oscillations induced by the varying tooth mesh stiffnesses of the gear pairs cause severe vibration in gear systems. The oscillations become more complex and serious in multi-mesh gear system because more mesh stiffnesses variation occur, which are necessary to be investigated in deeply. To illustrate the complex oscillation phenomena, a 8 degrees of freedom (DOF) non-linear dynamic model of a multi-mesh gear system is developed to study the responses of the system with considering time-varying mesh stiffnesses. Interactions between the mesh stiffness variations at the two meshes are examined. Seven different mesh phases are defined according to the alternating engagement of single and double gear teeth. The effects of different phases of the mesh stiffnesses between the two meshes on the typical multi-mesh gear system are identified by using numerical simulation. The results show that the oscillations of the multi-mesh gear system could be reduced by changing the phase of the mesh stiffnesses.

Meshing and Bearing Analysis of Nutation Drive with Face Gear

2020 ◽  
Vol 13 (4) ◽  
pp. 352-365
Author(s):  
Guangxin Wang ◽  
Lili Zhu ◽  
Peng Wang ◽  
Jia Deng
Keyword(s):  
Contact Stress ◽  
High Efficiency ◽  
Transmission Ratio ◽  
Contact Strength ◽  
Hertz Contact ◽  
Face Gear ◽  
Compact Structure ◽  
Gear Teeth ◽  
Gear Drive ◽  
Number Of Teeth

Background: Nutation drive is being extensively investigated due to its ability to achieve a high reduction ratio with a compact structure and the potential for low vibration, high efficiency and design flexibility. However, many problems including the difficulty to process the inner bevel gear, less number of teeth in engagement and not being suitable for high-power transmission have restricted its development. Objective: The purpose of this paper is to analyze the contact strength of a patent about a new nutation drive developed based on meshing between two face gears, which has the advantages of both face gear and nutation drive, including large transmission ratio, large coincidence, small size, compact structure and strong bearing capacity. Methods: Based on the meshing principle and basic structure of the nutation face gear drive, the contact strength of nutation face gear transmission is analyzed by the Hertz contact analysis method and FEM method. Results: The maximum stress values of nutation face gear teeth are compared by two methods, which verify the accuracy of Hertz contact analytical method in calculating the contact strength of nutation face gear teeth. Furthermore, nine groups of three-dimensional models for the nutation face gear drive with a transmission ratio of 52 and different cutter parameters are established. Conclusion: The study analyzes the contact stress of fixed and rotary face gears in meshing with planetary face gears, and obtains the distribution law of contact stress and the influence of the number of teeth and parameters of the cutter on the load-carrying capacity.

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