Aiming at the problem that aerodynamic uplift forces of the pantograph running in the knuckle-downstream and knuckle-upstream conditions are inconsistent,and their magnitudes do not satisfy the corresponding standard,...Aiming at the problem that aerodynamic uplift forces of the pantograph running in the knuckle-downstream and knuckle-upstream conditions are inconsistent,and their magnitudes do not satisfy the corresponding standard, the aerodynamic uplift forces of pantographs with baffles are numerically investigated, and an optimization method to determine the baffle angle is proposed. First, the error between the aerodynamic resistances of the pantograph obtained by numerical simulation and wind tunnel test is less than 5%, which indicates the accuracy of the numerical simulation method. Second, the original pantograph and pantographs equipped with three different baffles are numerically simulated to obtain the aerodynamic forces and moments of the pantograph components.Three different angles for the baffles are-17°, 0° and 17°.Then the multibody simulation is used to calculate the aerodynamic uplift force of the pantograph, and the optimal range for the baffle angle is determined. Results show that the lift force of the baffle increases with the increment of the angle in the knuckle-downstream condition, whereas the lift force of the baffle decreases with the increment of the angle in the knuckle-upstream condition. According to the results of the aerodynamic uplift force, the optimal angle of the baffle is determined to be 4.75° when the running speed is 350 km/h, and pantograph–catenary contact forces are 128.89 N and 129.15 N under the knuckledownstream and knuckle-upstream operating conditions,respectively, which are almost equal and both meet the requirements of the standard EN50367:2012.展开更多
The development of numerical models able to compute the wheel and rail profile wear is essential to improve the scheduling of maintenance operations required to restore the original profile shapes.This work surveys th...The development of numerical models able to compute the wheel and rail profile wear is essential to improve the scheduling of maintenance operations required to restore the original profile shapes.This work surveys the main numerical models in the literature for the evaluation of the uniform wear of wheel and rail profiles.The standard structure of these tools includes a multibody simulation of the wheel-track coupled dynamics and a wear module implementing an experimental wear law.Therefore,the models are classified according to the strategy adopted for the worn profile update,ranging from models performing a single computation to models based on an online communication between the dynamic and wear modules.Nevertheless,the most common strategy nowadays relies on an iteration of dynamic simulations in which the profiles are left unchanged,with co-simulation techniques often adopted to increase the computational performances.Work is still needed to improve the accuracy of the current models.New experimental campaigns should be carried out to obtain refined wear coefficients and models,while strategies for the evaluation of both longitudinal and transversal wear,also considering the effects of tread braking,should be implemented to obtain accurate damage models.展开更多
There are several fatigue-based approaches that estimate the evolution of rolling contact fatigue(RCF) on rails over time and built to be used in tandem with multibody simulations of vehicle dynamics. However, most of...There are several fatigue-based approaches that estimate the evolution of rolling contact fatigue(RCF) on rails over time and built to be used in tandem with multibody simulations of vehicle dynamics. However, most of the models are not directly comparable with each other since they are based on different physical models even though they shall predict the same RCF damage at the end.This article studies different approaches to quantifying RCF and puts forward a measure for the degree of agreement between them. The methodological framework studies various steps in the RCF quantification procedure within the context of one another, identifies the ‘primary quantification step’ in each approach and compares results of the fatigue analyses. In addition to this, two quantities—‘similarity’ and ‘correlation’—have been put forward to give an indication of mutual agreement between models.Four widely used surface-based and sub-surface-based fatigue quantification approaches with varying complexities have been studied. Different operational cases corresponding to a metro vehicle operation in Austria have been considered for this study. Results showed that the best possible quantity to compare is the normalized damage increment per loading cycle coming from different approaches. Amongst the methods studied, approaches that included the load distribution step on the contact patch showed higher similarity and correlation in their results.While the different approaches might qualitatively agree on whether contact cases are ‘damaging’ due to RCF, they might not quantitatively correlate with the trends observed for damage increment values.展开更多
Hybrid locomotive concepts have been considered as a step towards converting the railway industry into a green transport mode.One of the challenges in integrating a hybrid locomotive in the train consist is that the b...Hybrid locomotive concepts have been considered as a step towards converting the railway industry into a green transport mode.One of the challenges in integrating a hybrid locomotive in the train consist is that the battery pack in the locomotive needs to be recharged during a long-haul trip which requires stopping of the train.A typical battery pack requires about 1 h to recharge which is unacceptable.With the improvement in the charging system,it is now possible that the same capacity battery pack could be recharged in 10–12 min which can be a competitive option for the railway companies.This paper proposes a method based on simulation to evaluate the positioning of charging stations on a train network.A typical example of a heavy haul train operation hauled by diesel-electric and hybrid locomotives is used to demonstrate the method by using simulation softwares.The result of the simulation study show that the method developed in this paper can be used to evaluate the state of charge(SoC)status of a hybrid locomotive along the track.It is also shown that the SoC status obtained by the simulation method can be further used to assess the positions of charging stations along the track at the design stage.展开更多
Modern agricultural tractors are complex systems,in which multiple physical(and technological)domains interact to reach a wide set of competing goals,including work operational performance and energy efficiency.This c...Modern agricultural tractors are complex systems,in which multiple physical(and technological)domains interact to reach a wide set of competing goals,including work operational performance and energy efficiency.This complexity translates to the dynamic,multi‐domain simulation models implemented to serve as digital twins,for rapid prototyping and effective pre‐tuning,prior to bench and on‐field testing.Consequently,a suitable simulation framework should have the capability to focus both on the vehicle as a whole and on individual subsystems.For each of the latter,multiple options should be available,with different levels of detail,to properly address the relevant phenomena,depending on the specific focus,for an optimal balance between accuracy and computation time.The methodology proposed here by the authors is based on the lumped parameter approach and integrates the models for the following subsystems in a modular context:internal combustion engine,hydromechanical transmission,vehicle body,and tyre–soil interaction.The model is completed by a load cycle module that generates stimulus time histories to reproduce the work load under real operating conditions.Traction capability is affected by vertical load on the wheels,which is even more relevant if the vehicle is travelling on an uncompacted soil and subject to a variable drawbar pull force as it is when ploughing.The vertical load is,in turn,heavily affected by vehicle dynamics,which can be accurately modelled via a full multibody implementation.The presented lumped parameter model is intended as a powerful simulation tool to evaluate tractor performance,both in terms of fuel consumption and traction dynamics,by considering the cascade phenomena from the wheel–ground interaction to the engine,passing through the dynamics of vehicle bodies and their mass transfer.Its capabilities and numerical results are presented for the simulation of a realistic ploughing operation.展开更多
The operating conditions of marine machinery are demanding,and their operational state significantly affects the safety of marine structures.Detecting faults is crucial for machinery health management and necessitates...The operating conditions of marine machinery are demanding,and their operational state significantly affects the safety of marine structures.Detecting faults is crucial for machinery health management and necessitates a highly precise diagnostic method.In this paper,we propose a fault diagnosis framework that employs transfer learning and dynamics simulation.A denoising convolutional autoencoder is used to reduce noise when monitoring vibration data in marine environments.To address the challenge of limited sample sizes in marine machinery fault data,a multibody dynamics simulation model is developed to acquire data under fault conditions.The fault features are extracted using a convolutional neural network model.Parameter transfer is applied to enhance the accuracy of fault diagnosis.The effectiveness and applicability of the framework are demonstrated through a case study of a bearing fault dataset.展开更多
基金supported by National Key Research and Development Program of China (No. 2020YFA0710902)National Natural Science Foundation of China (No. 52072319)+1 种基金National Natural Science Foundation of China (Nos. 52072319 and 12172308)State Key Laboratory of Traction Power (2019TPL_T02)。
文摘Aiming at the problem that aerodynamic uplift forces of the pantograph running in the knuckle-downstream and knuckle-upstream conditions are inconsistent,and their magnitudes do not satisfy the corresponding standard, the aerodynamic uplift forces of pantographs with baffles are numerically investigated, and an optimization method to determine the baffle angle is proposed. First, the error between the aerodynamic resistances of the pantograph obtained by numerical simulation and wind tunnel test is less than 5%, which indicates the accuracy of the numerical simulation method. Second, the original pantograph and pantographs equipped with three different baffles are numerically simulated to obtain the aerodynamic forces and moments of the pantograph components.Three different angles for the baffles are-17°, 0° and 17°.Then the multibody simulation is used to calculate the aerodynamic uplift force of the pantograph, and the optimal range for the baffle angle is determined. Results show that the lift force of the baffle increases with the increment of the angle in the knuckle-downstream condition, whereas the lift force of the baffle decreases with the increment of the angle in the knuckle-upstream condition. According to the results of the aerodynamic uplift force, the optimal angle of the baffle is determined to be 4.75° when the running speed is 350 km/h, and pantograph–catenary contact forces are 128.89 N and 129.15 N under the knuckledownstream and knuckle-upstream operating conditions,respectively, which are almost equal and both meet the requirements of the standard EN50367:2012.
文摘The development of numerical models able to compute the wheel and rail profile wear is essential to improve the scheduling of maintenance operations required to restore the original profile shapes.This work surveys the main numerical models in the literature for the evaluation of the uniform wear of wheel and rail profiles.The standard structure of these tools includes a multibody simulation of the wheel-track coupled dynamics and a wear module implementing an experimental wear law.Therefore,the models are classified according to the strategy adopted for the worn profile update,ranging from models performing a single computation to models based on an online communication between the dynamic and wear modules.Nevertheless,the most common strategy nowadays relies on an iteration of dynamic simulations in which the profiles are left unchanged,with co-simulation techniques often adopted to increase the computational performances.Work is still needed to improve the accuracy of the current models.New experimental campaigns should be carried out to obtain refined wear coefficients and models,while strategies for the evaluation of both longitudinal and transversal wear,also considering the effects of tread braking,should be implemented to obtain accurate damage models.
基金funding from the Shift2Rail Joint Undertaking (JU) under the European Union’s Horizon 2020 research and innovation programme under grant agreement (No. 826206)。
文摘There are several fatigue-based approaches that estimate the evolution of rolling contact fatigue(RCF) on rails over time and built to be used in tandem with multibody simulations of vehicle dynamics. However, most of the models are not directly comparable with each other since they are based on different physical models even though they shall predict the same RCF damage at the end.This article studies different approaches to quantifying RCF and puts forward a measure for the degree of agreement between them. The methodological framework studies various steps in the RCF quantification procedure within the context of one another, identifies the ‘primary quantification step’ in each approach and compares results of the fatigue analyses. In addition to this, two quantities—‘similarity’ and ‘correlation’—have been put forward to give an indication of mutual agreement between models.Four widely used surface-based and sub-surface-based fatigue quantification approaches with varying complexities have been studied. Different operational cases corresponding to a metro vehicle operation in Austria have been considered for this study. Results showed that the best possible quantity to compare is the normalized damage increment per loading cycle coming from different approaches. Amongst the methods studied, approaches that included the load distribution step on the contact patch showed higher similarity and correlation in their results.While the different approaches might qualitatively agree on whether contact cases are ‘damaging’ due to RCF, they might not quantitatively correlate with the trends observed for damage increment values.
文摘Hybrid locomotive concepts have been considered as a step towards converting the railway industry into a green transport mode.One of the challenges in integrating a hybrid locomotive in the train consist is that the battery pack in the locomotive needs to be recharged during a long-haul trip which requires stopping of the train.A typical battery pack requires about 1 h to recharge which is unacceptable.With the improvement in the charging system,it is now possible that the same capacity battery pack could be recharged in 10–12 min which can be a competitive option for the railway companies.This paper proposes a method based on simulation to evaluate the positioning of charging stations on a train network.A typical example of a heavy haul train operation hauled by diesel-electric and hybrid locomotives is used to demonstrate the method by using simulation softwares.The result of the simulation study show that the method developed in this paper can be used to evaluate the state of charge(SoC)status of a hybrid locomotive along the track.It is also shown that the SoC status obtained by the simulation method can be further used to assess the positions of charging stations along the track at the design stage.
基金Region of Emilia‐Romagna,Italy-POR FESR 2014–2020,Asse 1,Azione 1.2.2,Grant/Award Number:B51F18000370009。
文摘Modern agricultural tractors are complex systems,in which multiple physical(and technological)domains interact to reach a wide set of competing goals,including work operational performance and energy efficiency.This complexity translates to the dynamic,multi‐domain simulation models implemented to serve as digital twins,for rapid prototyping and effective pre‐tuning,prior to bench and on‐field testing.Consequently,a suitable simulation framework should have the capability to focus both on the vehicle as a whole and on individual subsystems.For each of the latter,multiple options should be available,with different levels of detail,to properly address the relevant phenomena,depending on the specific focus,for an optimal balance between accuracy and computation time.The methodology proposed here by the authors is based on the lumped parameter approach and integrates the models for the following subsystems in a modular context:internal combustion engine,hydromechanical transmission,vehicle body,and tyre–soil interaction.The model is completed by a load cycle module that generates stimulus time histories to reproduce the work load under real operating conditions.Traction capability is affected by vertical load on the wheels,which is even more relevant if the vehicle is travelling on an uncompacted soil and subject to a variable drawbar pull force as it is when ploughing.The vertical load is,in turn,heavily affected by vehicle dynamics,which can be accurately modelled via a full multibody implementation.The presented lumped parameter model is intended as a powerful simulation tool to evaluate tractor performance,both in terms of fuel consumption and traction dynamics,by considering the cascade phenomena from the wheel–ground interaction to the engine,passing through the dynamics of vehicle bodies and their mass transfer.Its capabilities and numerical results are presented for the simulation of a realistic ploughing operation.
基金supported by the National Natural Science Foundation of China(Grant No.52301401 and 52271348)Lingchuang Research Project of China National Nuclear Corpora-tion.
文摘The operating conditions of marine machinery are demanding,and their operational state significantly affects the safety of marine structures.Detecting faults is crucial for machinery health management and necessitates a highly precise diagnostic method.In this paper,we propose a fault diagnosis framework that employs transfer learning and dynamics simulation.A denoising convolutional autoencoder is used to reduce noise when monitoring vibration data in marine environments.To address the challenge of limited sample sizes in marine machinery fault data,a multibody dynamics simulation model is developed to acquire data under fault conditions.The fault features are extracted using a convolutional neural network model.Parameter transfer is applied to enhance the accuracy of fault diagnosis.The effectiveness and applicability of the framework are demonstrated through a case study of a bearing fault dataset.
