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Zaigang Chen - One of the best experts on this subject based on the ideXlab platform.
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vibration characteristics of railway locomotive induced by gear tooth Root Crack fault under transient conditions
Engineering Failure Analysis, 2020Co-Authors: Jianzheng Jiang, Zaigang Chen, Wanming Zhai, Tao Zhang, Yifan LiAbstract:Abstract Dynamic interactions between wheel and rail are becoming more intensified under the development of locomotive towards high-speed, heavy-haul and high-power directions, which are more likely to cause failures in gear transmission system of high-power heavy-haul electric locomotive. The dynamic impact of the locomotive gear transmission system becomes more drastic, especially for the extreme operation conditions, such as traction/braking process. Gear fault diagnosis under unsteady conditions has always been a hot and difficult research spot, and revealing of the gear fault vibration characteristics under the transient conditions is the premise and basis for effective fault detection and diagnosis. In order to reveal the gear fault vibration characteristics of railway locomotive dynamics system, a spatial dynamic model of a heavy-haul electric locomotive considering the dynamic coupling effect of gear transmission system is proposed based on the multibody dynamics theory in this paper. Then the dynamic responses of the locomotive under transient condition are obtained by considering the complicated excitations induced by the wheel-rail nonlinear contact, gear mesh and tooth Root Crack. The time-frequency analysis and angular synchronous average method are adopted to investigate the fault vibration feature of the tooth Root Crack. Finally, the distribution and variation of vibration characteristics of the gear tooth Root Crack fault evolution are revealed by condition indicators such as the Crest Factor (CF), Kurtosis (K), Fourth Order Figure of Merit (FM4), M6A, and M8A. The results indicate that: (1) the time-frequency analysis results of vibration acceleration of wheelset and bogie frame and dynamic mesh force could reflect the fundamental mesh frequency and its harmonics, however, only the vertical and longitudinal vibration acceleration of the wheelset and the gear dynamic mesh force could reflect the fault vibration characteristics in time-frequency analysis results; (2) the FM4, M6A and M8A values of locomotive system vibration signal could effectively reflect the Crack propagation on the dynamic features of the locomotive system after being processed by angular synchronous averaging method.
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vibration feature evolution of locomotive with tooth Root Crack propagation of gear transmission system
Mechanical Systems and Signal Processing, 2019Co-Authors: Zaigang Chen, Wanming Zhai, Kaiyun WangAbstract:Abstract As the prompt development of modern railway transportation towards high-speed and high load-capacity, the high-power locomotive is urgently required. Under this situation, the wheel–rail dynamic interaction is becoming more and more intensified which will deteriorate the vibration condition of the key elements of locomotive, such as the gear transmissions. Once gear failures are present, such as gear tooth Crack or breakage, it is likely to threaten the operation safety of the locomotive. Thus, deep insight into the fault features of the locomotive gear transmission is urgently necessary for prevention of the induced disastrous consequences. This paper is concentrated on the fault vibration feature extraction of a locomotive in presence of gear tooth Root Crack under the complicated dynamic excitations from both the gear transmissions and the nonlinear wheel–rail interactions. The locomotive–track coupled dynamics model considering the dynamic effect of the mechanical power transmission path is employed, and the time-varying mesh stiffness of the gear pair with tooth Root Crack fault and the rail geometric irregularities are then incorporated into the dynamics model to obtain the vibration responses. Then, angular synchronous average technique is proposed to enhance the fault vibration features, and the statistical indicators extracted in frequency domain are developed to reveal the evolution law for the Crack propagation scenarios along Crack depth or tooth width. The analyzed results indicate that the angular synchronous average technique could effectively reveal the fault vibration feature, and the M8A in the selected statistical indicators is most sensitive to the tooth Crack propagation in frequency domain.
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Fault Vibration Features of Heavy-Haul Locomotive with Tooth Root Crack in Gear Transmissions
2018 International Conference on Sensing Diagnostics Prognostics and Control (SDPC), 2018Co-Authors: Jianzheng Jiang, Zaigang Chen, Chunyan HeAbstract:High-power heavy-haul locomotive has already been the development trend of Chinese heavy load freight. As a vital equipment of the locomotive system, gear transmission system is usually employed to deliver the traction or the braking power between the traction motor and the wheel/rail contact interface. The increasing dynamic load of the gear transmission induced by the raising of locomotive traction or braking power is likely to cause failures to the gear transmission system, which will affect the reliability and safety of the railway vehicles. This paper established a spatial dynamics model of high-power heavy-haul locomotive considering dynamic effect of the gear transmission based on the multibody dynamics theory in which the gear transmission is established as a sub-model. The time-varying mesh stiffness of the gear pair with tooth Root Crack was obtained by `slice method' which is an analytical mesh stiffness calculation approach based on the potential energy principle. The fault vibration characteristics of the gear transmission under the complicated excitations from the wheel/rail nonlinear contact, the rail geometric irregularity, and the periodic gear mesh process are studied.
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improved analytical methods for calculation of gear tooth fillet foundation stiffness with tooth Root Crack
Engineering Failure Analysis, 2017Co-Authors: Zaigang Chen, Wanming Zhai, Jie Zhang, Yawen WangAbstract:Abstract Two improved analytical calculation models of gear tooth fillet-foundation stiffness are proposed for spur gears with tooth Root Crack. The proposed two models are capable of taking tooth Root Crack into account in the calculation of gear tooth fillet-foundation stiffness. For Model-1, the reduction of gear tooth fillet-foundation stiffness is assumed to be the production of the stiffness under healthy condition and the ratio of the Crack length to the tooth thickness along the potential Crack path. While in Model-2, the stiffness of the gear tooth fillet-foundation is calculated by updating related geometrical parameters in the traditional calculation formulas for the healthy gears according to the variation of the load carrying zone due to tooth Root Crack. The two calculation models for calculating the tooth fillet-foundation stiffness of Cracked gears are verified by the finite element method (FEM). The results show that model-1 has a relatively poor accuracy for large Crack cases when the position of applied force is close to the tooth Root, while model-2 has a higher accuracy for both small and large Crack length. The proposed models can be employed to improve the accuracy of gear mesh stiffness calculation and assist gear faults detection and diagnosis.
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analytical model for mesh stiffness calculation of spur gear pair with non uniformly distributed tooth Root Crack
Engineering Failure Analysis, 2016Co-Authors: Zaigang Chen, Yimin Shao, Wanming Zhai, Kaiyun WangAbstract:Abstract Gear tooth Crack is likely to happen when a gear transmission train is working under excessive and/or long-term dynamic loads. Its appearance will reduce the effective tooth thickness for load carrying, and thus cause a reduction in mesh stiffness and influence the dynamic responses of the gear transmission system, which enables the possibility for gear fault detection from variations of the dynamic features. Accurate mesh stiffness calculation is required for improving the prediction accuracy of the dynamic features with respect to the tooth Crack fault. In this paper, an analytical mesh stiffness calculation model for non-uniformly distributed tooth Root Crack along tooth width is proposed based on previous studies. It enables a good prediction on the mesh stiffness for a spur gear pair with both incipient and larger tooth Cracks. This method is verified by comparisons with other analytical models and finite element model (FEM) in previous papers. Finally, a dynamic model of a gear transmission train is developed to simulate the dynamic responses when Cracks with different dimensions are seeded in a gear tooth, which could reveal the effect of the tooth Root Crack on the dynamic responses of the gear transmission system. The results indicate that both the mesh stiffness and the dynamic response results show that the proposed analytical model is an alternative method for mesh stiffness calculation of Cracked spur gear pairs with a good accuracy for both small and large Cracks.
Yimin Shao - One of the best experts on this subject based on the ideXlab platform.
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analytical model for mesh stiffness calculation of spur gear pair with non uniformly distributed tooth Root Crack
Engineering Failure Analysis, 2016Co-Authors: Zaigang Chen, Yimin Shao, Wanming Zhai, Kaiyun WangAbstract:Abstract Gear tooth Crack is likely to happen when a gear transmission train is working under excessive and/or long-term dynamic loads. Its appearance will reduce the effective tooth thickness for load carrying, and thus cause a reduction in mesh stiffness and influence the dynamic responses of the gear transmission system, which enables the possibility for gear fault detection from variations of the dynamic features. Accurate mesh stiffness calculation is required for improving the prediction accuracy of the dynamic features with respect to the tooth Crack fault. In this paper, an analytical mesh stiffness calculation model for non-uniformly distributed tooth Root Crack along tooth width is proposed based on previous studies. It enables a good prediction on the mesh stiffness for a spur gear pair with both incipient and larger tooth Cracks. This method is verified by comparisons with other analytical models and finite element model (FEM) in previous papers. Finally, a dynamic model of a gear transmission train is developed to simulate the dynamic responses when Cracks with different dimensions are seeded in a gear tooth, which could reveal the effect of the tooth Root Crack on the dynamic responses of the gear transmission system. The results indicate that both the mesh stiffness and the dynamic response results show that the proposed analytical model is an alternative method for mesh stiffness calculation of Cracked spur gear pairs with a good accuracy for both small and large Cracks.
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fault feature analysis of planetary gear system with tooth Root Crack and flexible ring gear rim
Engineering Failure Analysis, 2015Co-Authors: Zaigang Chen, Yimin ShaoAbstract:Abstract Planetary gear transmission has a wide application in different areas due to its advantages such as compactness, large torque-to-weight ratio, reduced noise and vibrations. However, its dynamic responses are much more complex due to the complicated structures and relative motions, which make it difficult in the fault feature extractions at the view point of fault detection. Better understanding on the dynamic features of a planetary gear transmission and the corresponding internal excitation sources will benefit the fault feature extractions. In this paper, an analytical model for mesh stiffness calculation is developed based on the potential energy principle and uniformly curved Timoshenko beam theory, which enables exploring the effects of the tooth Root Crack fault and the flexible ring gear rim on the dynamic responses. Based on the developed model, the frequency spectrum structures of the planetary gear transmission can be revealed and analyzed theoretically in the presence of tooth Crack and flexible ring gear. A case study is performed to demonstrate the effectiveness of the developed model, where the tooth Root Cracks are seeded in a tooth of the sun, planet, and ring gears. The simulated results indicate that the complicated modulation phenomenon can be observed where the causes of different frequency components can be revealed. This study is expected to be able to give some theoretical guidance on the identification of vibration sources for planetary gear transmissions.
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dynamic features of planetary gear set with tooth plastic inclination deformation due to tooth Root Crack
Nonlinear Dynamics, 2013Co-Authors: Yimin Shao, Zaigang ChenAbstract:Gear tooth Root Crack, as one of the popular gear tooth failures, is always caused by the dynamic load or excessive load applied to the tooth. It will devastate the working performance of the gear system, by problems such as vibration and noise, or even lead to a broken tooth, which will stop the normal working process of the gear system. It has attracted wide attention from researchers. However, the previous studies focused their concentration only on the mesh stiffness reduction due to tooth Root Crack, while the tooth plastic inclination due to tooth bending damages like gear tooth Root Crack is seldom considered. In this paper, a tooth plastic inclination model for spur gear with tooth Root Crack is developed by regarding the Cracked tooth as a cantilever beam. It influences not only the displacement excitation but also the mesh stiffness and load-sharing factor among tooth pairs in mesh. The simulation results obtained by incorporating the tooth plastic inclination deformation model together with the tooth Root Crack model into a 21-Degree-of-Freedom planetary gear dynamic model indicate that the tooth plastic inclination has a significant effect on the performance of the gear system rather than the mesh stiffness reduction due to tooth Root Crack.
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dynamic simulation of planetary gear with tooth Root Crack in ring gear
Engineering Failure Analysis, 2013Co-Authors: Zaigang Chen, Yimin ShaoAbstract:Abstract Planetary gear is widely used in different areas due to its advantages such as compactness, large torque-to-weight ratio, large transmission ratios, reduced noise and vibrations. However, the tooth faults like Cracks are seldom concentrated. In this paper, a mesh stiffness model of internal gear pair with a tooth Root Crack in the ring gear is derived based on the potential energy principle. The mesh stiffness model is incorporated into the dynamic model of a one-stage planetary gear set with 21-degree-of-freedom (DOF) to investigate the effect of the internal gear tooth Root Crack. The Crack cases with different dimensions are designed in this paper to demonstrate their influences on the mesh stiffness and the dynamic performance of the planetary gear set. The simulated results show that bigger reduction in mesh stiffness is caused by the growth in the Crack size. And the impulsive vibrations and sidebands can be observed in the dynamic response of the planetary gear set in time and frequency domains, respectively. Both their amplitudes increase as the Crack propagation which supply the possibility for them to be the indicators in the condition monitoring and fault diagnosis of planetary gear system.
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dynamic features of a planetary gear system with tooth Crack under different sizes and inclination angles
Journal of Vibration and Acoustics, 2013Co-Authors: Zaigang Chen, Yimin ShaoAbstract:Planetary gears are widely used in the industry due to their advantages of compactness, high power-to-weight ratios, high efficiency, and so on. However, planetary gears such as that in wind turbine transmissions always operate under dynamic conditions with internal and external load fluctuations, which accelerate the occurrence of gear failures, such as tooth Crack, pitting, spalling, wear, scoring, scuffing, etc. As one of these failure modes, gear tooth Crack at the tooth Root due to tooth bending fatigue or excessive load is investigated; how it influences the dynamic features of planetary gear system is studied. The applied tooth Root Crack model can simulate the propagation process of the Crack along tooth width and Crack depth. With this approach, the mesh stiffness of gear pairs in mesh is obtained and incorporated into a planetary gear dynamic model to investigate the effects of the tooth Root Crack on the planetary gear dynamic responses. Tooth Root Cracks on the sun gear and on the planet gear are considered, respectively, with different Crack sizes and inclination angles. Finally, analysis regarding the influence of tooth Root Crack on the dynamic responses of the planetary gear system is performed in time and frequency domains, respectively. Moreover, the differences in the dynamic features of the planetary gear between the cases that tooth Root Crack on the sun gear and on the planet gear are found.
Kaiyun Wang - One of the best experts on this subject based on the ideXlab platform.
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vibration feature evolution of locomotive with tooth Root Crack propagation of gear transmission system
Mechanical Systems and Signal Processing, 2019Co-Authors: Zaigang Chen, Wanming Zhai, Kaiyun WangAbstract:Abstract As the prompt development of modern railway transportation towards high-speed and high load-capacity, the high-power locomotive is urgently required. Under this situation, the wheel–rail dynamic interaction is becoming more and more intensified which will deteriorate the vibration condition of the key elements of locomotive, such as the gear transmissions. Once gear failures are present, such as gear tooth Crack or breakage, it is likely to threaten the operation safety of the locomotive. Thus, deep insight into the fault features of the locomotive gear transmission is urgently necessary for prevention of the induced disastrous consequences. This paper is concentrated on the fault vibration feature extraction of a locomotive in presence of gear tooth Root Crack under the complicated dynamic excitations from both the gear transmissions and the nonlinear wheel–rail interactions. The locomotive–track coupled dynamics model considering the dynamic effect of the mechanical power transmission path is employed, and the time-varying mesh stiffness of the gear pair with tooth Root Crack fault and the rail geometric irregularities are then incorporated into the dynamics model to obtain the vibration responses. Then, angular synchronous average technique is proposed to enhance the fault vibration features, and the statistical indicators extracted in frequency domain are developed to reveal the evolution law for the Crack propagation scenarios along Crack depth or tooth width. The analyzed results indicate that the angular synchronous average technique could effectively reveal the fault vibration feature, and the M8A in the selected statistical indicators is most sensitive to the tooth Crack propagation in frequency domain.
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analytical model for mesh stiffness calculation of spur gear pair with non uniformly distributed tooth Root Crack
Engineering Failure Analysis, 2016Co-Authors: Zaigang Chen, Yimin Shao, Wanming Zhai, Kaiyun WangAbstract:Abstract Gear tooth Crack is likely to happen when a gear transmission train is working under excessive and/or long-term dynamic loads. Its appearance will reduce the effective tooth thickness for load carrying, and thus cause a reduction in mesh stiffness and influence the dynamic responses of the gear transmission system, which enables the possibility for gear fault detection from variations of the dynamic features. Accurate mesh stiffness calculation is required for improving the prediction accuracy of the dynamic features with respect to the tooth Crack fault. In this paper, an analytical mesh stiffness calculation model for non-uniformly distributed tooth Root Crack along tooth width is proposed based on previous studies. It enables a good prediction on the mesh stiffness for a spur gear pair with both incipient and larger tooth Cracks. This method is verified by comparisons with other analytical models and finite element model (FEM) in previous papers. Finally, a dynamic model of a gear transmission train is developed to simulate the dynamic responses when Cracks with different dimensions are seeded in a gear tooth, which could reveal the effect of the tooth Root Crack on the dynamic responses of the gear transmission system. The results indicate that both the mesh stiffness and the dynamic response results show that the proposed analytical model is an alternative method for mesh stiffness calculation of Cracked spur gear pairs with a good accuracy for both small and large Cracks.
Wanming Zhai - One of the best experts on this subject based on the ideXlab platform.
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vibration characteristics of railway locomotive induced by gear tooth Root Crack fault under transient conditions
Engineering Failure Analysis, 2020Co-Authors: Jianzheng Jiang, Zaigang Chen, Wanming Zhai, Tao Zhang, Yifan LiAbstract:Abstract Dynamic interactions between wheel and rail are becoming more intensified under the development of locomotive towards high-speed, heavy-haul and high-power directions, which are more likely to cause failures in gear transmission system of high-power heavy-haul electric locomotive. The dynamic impact of the locomotive gear transmission system becomes more drastic, especially for the extreme operation conditions, such as traction/braking process. Gear fault diagnosis under unsteady conditions has always been a hot and difficult research spot, and revealing of the gear fault vibration characteristics under the transient conditions is the premise and basis for effective fault detection and diagnosis. In order to reveal the gear fault vibration characteristics of railway locomotive dynamics system, a spatial dynamic model of a heavy-haul electric locomotive considering the dynamic coupling effect of gear transmission system is proposed based on the multibody dynamics theory in this paper. Then the dynamic responses of the locomotive under transient condition are obtained by considering the complicated excitations induced by the wheel-rail nonlinear contact, gear mesh and tooth Root Crack. The time-frequency analysis and angular synchronous average method are adopted to investigate the fault vibration feature of the tooth Root Crack. Finally, the distribution and variation of vibration characteristics of the gear tooth Root Crack fault evolution are revealed by condition indicators such as the Crest Factor (CF), Kurtosis (K), Fourth Order Figure of Merit (FM4), M6A, and M8A. The results indicate that: (1) the time-frequency analysis results of vibration acceleration of wheelset and bogie frame and dynamic mesh force could reflect the fundamental mesh frequency and its harmonics, however, only the vertical and longitudinal vibration acceleration of the wheelset and the gear dynamic mesh force could reflect the fault vibration characteristics in time-frequency analysis results; (2) the FM4, M6A and M8A values of locomotive system vibration signal could effectively reflect the Crack propagation on the dynamic features of the locomotive system after being processed by angular synchronous averaging method.
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vibration feature evolution of locomotive with tooth Root Crack propagation of gear transmission system
Mechanical Systems and Signal Processing, 2019Co-Authors: Zaigang Chen, Wanming Zhai, Kaiyun WangAbstract:Abstract As the prompt development of modern railway transportation towards high-speed and high load-capacity, the high-power locomotive is urgently required. Under this situation, the wheel–rail dynamic interaction is becoming more and more intensified which will deteriorate the vibration condition of the key elements of locomotive, such as the gear transmissions. Once gear failures are present, such as gear tooth Crack or breakage, it is likely to threaten the operation safety of the locomotive. Thus, deep insight into the fault features of the locomotive gear transmission is urgently necessary for prevention of the induced disastrous consequences. This paper is concentrated on the fault vibration feature extraction of a locomotive in presence of gear tooth Root Crack under the complicated dynamic excitations from both the gear transmissions and the nonlinear wheel–rail interactions. The locomotive–track coupled dynamics model considering the dynamic effect of the mechanical power transmission path is employed, and the time-varying mesh stiffness of the gear pair with tooth Root Crack fault and the rail geometric irregularities are then incorporated into the dynamics model to obtain the vibration responses. Then, angular synchronous average technique is proposed to enhance the fault vibration features, and the statistical indicators extracted in frequency domain are developed to reveal the evolution law for the Crack propagation scenarios along Crack depth or tooth width. The analyzed results indicate that the angular synchronous average technique could effectively reveal the fault vibration feature, and the M8A in the selected statistical indicators is most sensitive to the tooth Crack propagation in frequency domain.
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improved analytical methods for calculation of gear tooth fillet foundation stiffness with tooth Root Crack
Engineering Failure Analysis, 2017Co-Authors: Zaigang Chen, Wanming Zhai, Jie Zhang, Yawen WangAbstract:Abstract Two improved analytical calculation models of gear tooth fillet-foundation stiffness are proposed for spur gears with tooth Root Crack. The proposed two models are capable of taking tooth Root Crack into account in the calculation of gear tooth fillet-foundation stiffness. For Model-1, the reduction of gear tooth fillet-foundation stiffness is assumed to be the production of the stiffness under healthy condition and the ratio of the Crack length to the tooth thickness along the potential Crack path. While in Model-2, the stiffness of the gear tooth fillet-foundation is calculated by updating related geometrical parameters in the traditional calculation formulas for the healthy gears according to the variation of the load carrying zone due to tooth Root Crack. The two calculation models for calculating the tooth fillet-foundation stiffness of Cracked gears are verified by the finite element method (FEM). The results show that model-1 has a relatively poor accuracy for large Crack cases when the position of applied force is close to the tooth Root, while model-2 has a higher accuracy for both small and large Crack length. The proposed models can be employed to improve the accuracy of gear mesh stiffness calculation and assist gear faults detection and diagnosis.
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analytical model for mesh stiffness calculation of spur gear pair with non uniformly distributed tooth Root Crack
Engineering Failure Analysis, 2016Co-Authors: Zaigang Chen, Yimin Shao, Wanming Zhai, Kaiyun WangAbstract:Abstract Gear tooth Crack is likely to happen when a gear transmission train is working under excessive and/or long-term dynamic loads. Its appearance will reduce the effective tooth thickness for load carrying, and thus cause a reduction in mesh stiffness and influence the dynamic responses of the gear transmission system, which enables the possibility for gear fault detection from variations of the dynamic features. Accurate mesh stiffness calculation is required for improving the prediction accuracy of the dynamic features with respect to the tooth Crack fault. In this paper, an analytical mesh stiffness calculation model for non-uniformly distributed tooth Root Crack along tooth width is proposed based on previous studies. It enables a good prediction on the mesh stiffness for a spur gear pair with both incipient and larger tooth Cracks. This method is verified by comparisons with other analytical models and finite element model (FEM) in previous papers. Finally, a dynamic model of a gear transmission train is developed to simulate the dynamic responses when Cracks with different dimensions are seeded in a gear tooth, which could reveal the effect of the tooth Root Crack on the dynamic responses of the gear transmission system. The results indicate that both the mesh stiffness and the dynamic response results show that the proposed analytical model is an alternative method for mesh stiffness calculation of Cracked spur gear pairs with a good accuracy for both small and large Cracks.
Zhengjia He - One of the best experts on this subject based on the ideXlab platform.
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an improved time varying mesh stiffness algorithm and dynamic modeling of gear rotor system with tooth Root Crack
Engineering Failure Analysis, 2014Co-Authors: Yanyang Zi, Wangpeng He, Zhengjia HeAbstract:Abstract When a tooth Crack failure occurs, the vibration response characteristics caused by the change of time-varying mesh stiffness play an important role in Crack fault diagnosis. In this paper, an improved time-varying mesh stiffness algorithm is presented. A coupled lateral and torsional vibration dynamic model is used to simulate the vibration response of gear-rotor system with tooth Crack. The effects of geometric transmission error (GTE), bearing stiffness, and gear mesh stiffness on the dynamic model are analyzed. The simulation results show that the gear dynamic response is periodic impulses due to the periodic sudden change of time varying mesh stiffness. When the Cracked tooth comes in contact, the impulse amplitude will increase as a result of reductions of mesh stiffness. Amplitude modulation phenomenon caused by GTE can be found in the simulation signal. The lateral–torsional coupling frequency increases greatly within certain limits and thereafter reaches a constant while the lateral natural frequency nearly remains constant as the gear mesh stiffness increases. Finally, an experiment was conducted on a test bench with 2 mm Root Crack fault. The results of experiment agree well with those obtained by simulation. The proposed method improves the accuracy of using potential energy method to calculate the time-varying mesh stiffness and expounds the vibration mechanism of gear-rotor system with tooth Crack failure.
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An improved time-varying mesh stiffness algorithm and dynamic modeling of gear-rotor system with tooth Root Crack
Engineering Failure Analysis, 2014Co-Authors: Zhiguo Wan, Hongrui Cao, Wangpeng He, Yanyang Zi, Zhengjia HeAbstract:When a tooth Crack failure occurs, the vibration response characteristics caused by the change of time-varying mesh stiffness play an important role in Crack fault diagnosis. In this paper, an improved time-varying mesh stiffness algorithm is presented. A coupled lateral and torsional vibration dynamic model is used to simulate the vibration response of gear-rotor system with tooth Crack. The effects of geometric transmission error (GTE), bearing stiffness, and gear mesh stiffness on the dynamic model are analyzed. The simulation results show that the gear dynamic response is periodic impulses due to the periodic sudden change of time varying mesh stiffness. When the Cracked tooth comes in contact, the impulse amplitude will increase as a result of reductions of mesh stiffness. Amplitude modulation phenomenon caused by GTE can be found in the simulation signal. The lateral-torsional coupling frequency increases greatly within certain limits and thereafter reaches a constant while the lateral natural frequency nearly remains constant as the gear mesh stiffness increases. Finally, an experiment was conducted on a test bench with 2. mm Root Crack fault. The results of experiment agree well with those obtained by simulation. The proposed method improves the accuracy of using potential energy method to calculate the time-varying mesh stiffness and expounds the vibration mechanism of gear-rotor system with tooth Crack failure. © 2014 Elsevier Ltd.
