Induction motors, as typical electromechanical energy conversion devices, have received limited attention in previous studies on electromechanical coupling vibrations, precise modeling, and the use of electromechanica...Induction motors, as typical electromechanical energy conversion devices, have received limited attention in previous studies on electromechanical coupling vibrations, precise modeling, and the use of electromechanical coupling effects for fault diagnosis and condition assessment in motor drive systems. This study proposes a comprehensive model of cage induction motors that integrates the multiple coupled circuit model with a rotor-bearing dynamics model. The model accounts for the linear increase in the magnetomotive force across the slot and incorporates the skidding characteristics of bearings in the rotor-bearing system. By calculating the time-varying mutual inductance parameters based on the air-gap distribution in the vibration environment, the electromechanical coupling vibration of the cage motor is investigated. Furthermore, this study examines the electromechanical coupling vibration characteristics influenced by various factors, including bearing clearances, radial loads, and the vertical excitation frequencies of the stators. The results show that the proposed model improves the excitation inputs for the electrical and mechanical systems of the motor compared with conventional models. Increased bearing clearance and radial load affect the current and torque similarly but have opposite effects on the slip ratio. This study provides a deeper understanding of electromechanical coupling mechanisms and facilitates the use of such phenomena for fault diagnosis and condition assessment in motor-driven systems.展开更多
Gear mesh excitations are widely concerned in the dynamic studies of the gear transmission system.Meanwhile,intentional and unintentional tooth profile deviations often occur in gears.At present,the established calcul...Gear mesh excitations are widely concerned in the dynamic studies of the gear transmission system.Meanwhile,intentional and unintentional tooth profile deviations often occur in gears.At present,the established calculation models of gear mesh excitations consider tooth profile deviations as displacement excitation.However,gear mesh excitations calculated by such models have reduced stability compared with the actual situation.Therefore,in this study,an improved analytical model of gear mesh excitations with tooth profile deviations is established.This established model considers tooth profile deviations,extended tooth contact,and the structure coupling effect of the gear body simultaneously.More importantly,the model considers the strong correlation among tooth contact parameters,contact force,and tooth profile deviations to better reflect the actual gear mesh.A calculation flowchart with a simple calculation method of contact forces is also proposed to calculate the gear mesh excitations.Finally,the effects of tooth profile deviations on gear mesh excitations are studied.The results show that the effects of tooth profile deviations on tooth contact position,the direction of contact force,and equivalent basic circle radii should be considered in the calculation of gear mesh excitations because of smaller system transmission errors,larger double-teeth meshing area,and slighter extended tooth contact.Tooth profile deviations also cause jumps in tooth contact position and time-varying mesh stiffness.Thus,our findings show that the proposed model can be used to calculate the gear mesh excitations more accurately when the tooth profile deviates greatly.展开更多
As one of the most typical fault forms of the helical gear,the crack will change the dynamic excitation and further affect the dynamic behaviors of the transmission systems.Due to the complicated structure of the heli...As one of the most typical fault forms of the helical gear,the crack will change the dynamic excitation and further affect the dynamic behaviors of the transmission systems.Due to the complicated structure of the helical gears,the coupling effect between the neighboring loaded teeth is usually ignored in the mesh stiffness calculation,making it considerably overestimated especially in the case of the crack fault.An improved mesh stiffness calculation method of helical gear with spatial crack is proposed to make up this gap.The interactions between the loaded neighboring teeth induced by the gear body flexibility were considered to improve the calculation accuracy and applicability.Besides,the load distribution law for the engaged cracked tooth along the tooth width and profile can be obtained.The results indicated that the mesh stiffness of the multi-tooth engagement calculation using this model could be further improved compared with the traditional methods.Finally,the effects of the helix angle,crack depth,and crack propagation length on the mesh stiffness and load distribution were investigated using the proposed method.展开更多
Tooth profile shift will change the thickness of gear teeth and a part of geometrical parameters of a gear pair, thus influencing its mesh stiffness and consequently the dynamic performances. In this paper, an analyti...Tooth profile shift will change the thickness of gear teeth and a part of geometrical parameters of a gear pair, thus influencing its mesh stiffness and consequently the dynamic performances. In this paper, an analytical mesh stiffness calculation model for an internal gear pair in mesh considering the tooth profile shift is developed based on the potential energy principle. Geometrical representations of the tooth profile shift are firstly derived, and then fitted into the analytical tooth stiffness model of gears. This model could supply a convenient way for mesh stiffness calculation of profile shifted spur gears. Then, simulation studies are conducted based on the developed model to demonstrate the effects of tooth profile shift coefficient on the tooth compliances and the mesh stiffness of the internal spur gear pair. The results show that tooth profile shift has an obvious influence on the mean value, amplitude variation and phase of the mesh stiffness, from which it can be predicted that the dynamic response of an internal gear transmission system will be affected by the tooth profile shift.展开更多
Based on the theory of vehicle-track coupled dynamics and gear system dynamics, a locomotive-track coupled spatial dynamics model is established by considering the dynamic effects of the gear transmission system. The ...Based on the theory of vehicle-track coupled dynamics and gear system dynamics, a locomotive-track coupled spatial dynamics model is established by considering the dynamic effects of the gear transmission system. The vibration responses of a locomotive's major components are then simulated using three locomotive-track models, namely the proposed dynamics model with the gear transmissions, a locomotive-track coupled dynamics model that considers the traction motor, and the classical Zhai's model. The locomotive dynamic responses of the three models are extracted and compared to reveal discrepancies between them so as to explore the dynamic effects of the power transmission system and clarify potential applications of these models. The results indicate that the dynamic effects of the gear transmissions have a negligible influence on the lateral vibrations of the locomotive components. However, they have obvious effects on the vertical and longitudinal vibrations of the wheelset and the traction motor. Another advantage of the locomotive dynamics model that considers the dynamic effects of the gear transmissions is that the dynamic performance of the drive system can be assessed in the vehicle vibration environment. This study provides theoretical references that can assist researchers in choosing the most appropriate locomotive dynamics model according to their specific research purpose.展开更多
Wear is a major cause of bearing failure,however,compared with other impact failures,smooth wear is often neglected because of its slow gradualness.In a locomotive,under the effect of the intensified wheel-rail intera...Wear is a major cause of bearing failure,however,compared with other impact failures,smooth wear is often neglected because of its slow gradualness.In a locomotive,under the effect of the intensified wheel-rail interaction and gear mesh,the surface wear can increase the radial clearances of motor bearings,trigger abnormal vibration and noise,and adversely affect the efficiency and safety of the traction motor.In this study,considering the mechanical structure of the traction motor,a locomotive-track spatially coupled dynamics model with traction power transmissions(LTMM)is adopted to provide accurate dynamic loads and obtain the dynamic responses of the system.From the perspective of contact stress and relative skidding at the roller-race interface,the causes and evolution of motor bearings surface wear are analyzed.The results indicate that the wear of inner races of motor bearings is uniform.The outer races of the driving/non-driving end bearings(DB or NDB)are worn in the loaded/main loadbearing regions.The increasing surface wear can increase the internal dynamic forces(e.g.,the centrifugal force of rotor and unbalanced magnetic pull)induced by the instantaneous eccentricity of the rotor,intensify the interactions between the roller and races,and deteriorate the vibrations of the traction motor and its neighboring components in the locomotive.In addition,the effects of the friction coefficient at the roller-race interface and track random irregularity are analyzed.This study offers a theoretical basis in service life prediction and design of the motor bearings.展开更多
Size and weight limitations mean that ordinary railway vehicles with two double-axle bogies cannot deliver some extremely heavy cargo and products.Thus,a newly designed high-speed freight electric multiple unit(EMU)eq...Size and weight limitations mean that ordinary railway vehicles with two double-axle bogies cannot deliver some extremely heavy cargo and products.Thus,a newly designed high-speed freight electric multiple unit(EMU)equipped with two bogie groups each with two double-axle bogies connected by a transition frame is an alternative means of transporting heavy products because of its greater load capacity.However,because it is still in the design stage,its dynamic performance is yet to be researched,something that is urgently required because of the more-complicated structure and more-intensive wheel-rail interactions than those of traditional high-speed railway vehicles.Therefore,to reveal the dynamic performance,this study establishes a three-dimensional dynamic model of a trailer vehicle in a high-speed freight EMU equipped with four double-axle bogies based on the classical theory of vehicle-track coupled dynamics.In this dynamic model,the vertical,horizontal,rolling,pitching,and yaw motions of the major components excited by random irregularities in the track geometry are considered fully.The results indicate that the derailment coefficient and stability index of this vehicle are both at excellent levels for the simulated conditions.The wheel unloading ratio appears to be larger but still within the safety range when the vehicle runs in a straight line,but it is close to or can even exceed the limit value when the vehicle runs at 400 km/h on a specified curved line.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos. 52022083, 52275132)。
文摘Induction motors, as typical electromechanical energy conversion devices, have received limited attention in previous studies on electromechanical coupling vibrations, precise modeling, and the use of electromechanical coupling effects for fault diagnosis and condition assessment in motor drive systems. This study proposes a comprehensive model of cage induction motors that integrates the multiple coupled circuit model with a rotor-bearing dynamics model. The model accounts for the linear increase in the magnetomotive force across the slot and incorporates the skidding characteristics of bearings in the rotor-bearing system. By calculating the time-varying mutual inductance parameters based on the air-gap distribution in the vibration environment, the electromechanical coupling vibration of the cage motor is investigated. Furthermore, this study examines the electromechanical coupling vibration characteristics influenced by various factors, including bearing clearances, radial loads, and the vertical excitation frequencies of the stators. The results show that the proposed model improves the excitation inputs for the electrical and mechanical systems of the motor compared with conventional models. Increased bearing clearance and radial load affect the current and torque similarly but have opposite effects on the slip ratio. This study provides a deeper understanding of electromechanical coupling mechanisms and facilitates the use of such phenomena for fault diagnosis and condition assessment in motor-driven systems.
基金supported by the National Key Rrsearch and Development Program of China(Grant No.2022YFB3402100)the National Natural Science Foundation of China(Grant Nos.52022083 and 52275132)。
文摘Gear mesh excitations are widely concerned in the dynamic studies of the gear transmission system.Meanwhile,intentional and unintentional tooth profile deviations often occur in gears.At present,the established calculation models of gear mesh excitations consider tooth profile deviations as displacement excitation.However,gear mesh excitations calculated by such models have reduced stability compared with the actual situation.Therefore,in this study,an improved analytical model of gear mesh excitations with tooth profile deviations is established.This established model considers tooth profile deviations,extended tooth contact,and the structure coupling effect of the gear body simultaneously.More importantly,the model considers the strong correlation among tooth contact parameters,contact force,and tooth profile deviations to better reflect the actual gear mesh.A calculation flowchart with a simple calculation method of contact forces is also proposed to calculate the gear mesh excitations.Finally,the effects of tooth profile deviations on gear mesh excitations are studied.The results show that the effects of tooth profile deviations on tooth contact position,the direction of contact force,and equivalent basic circle radii should be considered in the calculation of gear mesh excitations because of smaller system transmission errors,larger double-teeth meshing area,and slighter extended tooth contact.Tooth profile deviations also cause jumps in tooth contact position and time-varying mesh stiffness.Thus,our findings show that the proposed model can be used to calculate the gear mesh excitations more accurately when the tooth profile deviates greatly.
基金supported by the National Natural Science Foundation of China(Grant Nos.52022083,52275132 and 51735012)。
文摘As one of the most typical fault forms of the helical gear,the crack will change the dynamic excitation and further affect the dynamic behaviors of the transmission systems.Due to the complicated structure of the helical gears,the coupling effect between the neighboring loaded teeth is usually ignored in the mesh stiffness calculation,making it considerably overestimated especially in the case of the crack fault.An improved mesh stiffness calculation method of helical gear with spatial crack is proposed to make up this gap.The interactions between the loaded neighboring teeth induced by the gear body flexibility were considered to improve the calculation accuracy and applicability.Besides,the load distribution law for the engaged cracked tooth along the tooth width and profile can be obtained.The results indicated that the mesh stiffness of the multi-tooth engagement calculation using this model could be further improved compared with the traditional methods.Finally,the effects of the helix angle,crack depth,and crack propagation length on the mesh stiffness and load distribution were investigated using the proposed method.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51405400 & 51375403)the Fundamental Research Funds for the Central Universities (Grant Nos. 2682015ZD12 & 2682016CX125)the Fundamental Research Funds for State Key Laboratory of Traction Power (Grant Nos. 2015TPL_T14 & 2014TPL_T10)
文摘Tooth profile shift will change the thickness of gear teeth and a part of geometrical parameters of a gear pair, thus influencing its mesh stiffness and consequently the dynamic performances. In this paper, an analytical mesh stiffness calculation model for an internal gear pair in mesh considering the tooth profile shift is developed based on the potential energy principle. Geometrical representations of the tooth profile shift are firstly derived, and then fitted into the analytical tooth stiffness model of gears. This model could supply a convenient way for mesh stiffness calculation of profile shifted spur gears. Then, simulation studies are conducted based on the developed model to demonstrate the effects of tooth profile shift coefficient on the tooth compliances and the mesh stiffness of the internal spur gear pair. The results show that tooth profile shift has an obvious influence on the mean value, amplitude variation and phase of the mesh stiffness, from which it can be predicted that the dynamic response of an internal gear transmission system will be affected by the tooth profile shift.
基金supported by the National Natural Science Foundation of China(Grant Nos.51775453,51735012)the Sichuan Science and Technology Program(Grant No.2018JY0159)the open fund from the State Key Laboratory of Mechanical Transmissions of Chongqing University(Grant No.SKLMT-KFKT-201705)
文摘Based on the theory of vehicle-track coupled dynamics and gear system dynamics, a locomotive-track coupled spatial dynamics model is established by considering the dynamic effects of the gear transmission system. The vibration responses of a locomotive's major components are then simulated using three locomotive-track models, namely the proposed dynamics model with the gear transmissions, a locomotive-track coupled dynamics model that considers the traction motor, and the classical Zhai's model. The locomotive dynamic responses of the three models are extracted and compared to reveal discrepancies between them so as to explore the dynamic effects of the power transmission system and clarify potential applications of these models. The results indicate that the dynamic effects of the gear transmissions have a negligible influence on the lateral vibrations of the locomotive components. However, they have obvious effects on the vertical and longitudinal vibrations of the wheelset and the traction motor. Another advantage of the locomotive dynamics model that considers the dynamic effects of the gear transmissions is that the dynamic performance of the drive system can be assessed in the vehicle vibration environment. This study provides theoretical references that can assist researchers in choosing the most appropriate locomotive dynamics model according to their specific research purpose.
基金supported by the National Natural Science Foundation of China (Grant Nos. 52022083, 51775453, 51735012)
文摘Wear is a major cause of bearing failure,however,compared with other impact failures,smooth wear is often neglected because of its slow gradualness.In a locomotive,under the effect of the intensified wheel-rail interaction and gear mesh,the surface wear can increase the radial clearances of motor bearings,trigger abnormal vibration and noise,and adversely affect the efficiency and safety of the traction motor.In this study,considering the mechanical structure of the traction motor,a locomotive-track spatially coupled dynamics model with traction power transmissions(LTMM)is adopted to provide accurate dynamic loads and obtain the dynamic responses of the system.From the perspective of contact stress and relative skidding at the roller-race interface,the causes and evolution of motor bearings surface wear are analyzed.The results indicate that the wear of inner races of motor bearings is uniform.The outer races of the driving/non-driving end bearings(DB or NDB)are worn in the loaded/main loadbearing regions.The increasing surface wear can increase the internal dynamic forces(e.g.,the centrifugal force of rotor and unbalanced magnetic pull)induced by the instantaneous eccentricity of the rotor,intensify the interactions between the roller and races,and deteriorate the vibrations of the traction motor and its neighboring components in the locomotive.In addition,the effects of the friction coefficient at the roller-race interface and track random irregularity are analyzed.This study offers a theoretical basis in service life prediction and design of the motor bearings.
基金supported by the National Key R&D Program of China(Grant No.2017YFB1201300)the National Natural Science Foundation of China(Grant No.51775453)+1 种基金the Fundamental Research Funds for the State Key Laboratory of Traction Power of Southwest Jiaotong University(Grant No.2019TPL-T09)the Fundamental Research Funds for the Central Universities(Grant No.2682019YQ04)。
文摘Size and weight limitations mean that ordinary railway vehicles with two double-axle bogies cannot deliver some extremely heavy cargo and products.Thus,a newly designed high-speed freight electric multiple unit(EMU)equipped with two bogie groups each with two double-axle bogies connected by a transition frame is an alternative means of transporting heavy products because of its greater load capacity.However,because it is still in the design stage,its dynamic performance is yet to be researched,something that is urgently required because of the more-complicated structure and more-intensive wheel-rail interactions than those of traditional high-speed railway vehicles.Therefore,to reveal the dynamic performance,this study establishes a three-dimensional dynamic model of a trailer vehicle in a high-speed freight EMU equipped with four double-axle bogies based on the classical theory of vehicle-track coupled dynamics.In this dynamic model,the vertical,horizontal,rolling,pitching,and yaw motions of the major components excited by random irregularities in the track geometry are considered fully.The results indicate that the derailment coefficient and stability index of this vehicle are both at excellent levels for the simulated conditions.The wheel unloading ratio appears to be larger but still within the safety range when the vehicle runs in a straight line,but it is close to or can even exceed the limit value when the vehicle runs at 400 km/h on a specified curved line.
