In this work,a method is put forward to obtain the dynamic solution efficiently and accurately for a large-scale train-track-substructure(TTS)system.It is called implicit-explicit integration and multi-time-step solut...In this work,a method is put forward to obtain the dynamic solution efficiently and accurately for a large-scale train-track-substructure(TTS)system.It is called implicit-explicit integration and multi-time-step solution method(abbreviated as mI-nE-MTS method).The TTS system is divided into train-track subsystem and substruc-ture subsystem.Considering that the root cause of low effi-ciency of obtaining TTS solution lies in solving the alge-braic equation of the substructures,the high-efficient Zhai method,an explicit integration scheme,can be introduced to avoid matrix inversion process.The train-track system is solved by implicitly Park method.Moreover,it is known that the requirement of time step size differs for different sub-systems,integration methods and structural frequency response characteristics.A multi-time-step solution is pro-posed,in which time step size for the train-track subsystem and the substructure subsystem can be arbitrarily chosen once satisfying stability and precision demand,namely the time spent for m implicit integral steps is equal to n explicit integral steps,i.e.,mI=nE as mentioned above.The numeri-cal examples show the accuracy,efficiency,and engineering practicality of the proposed method.展开更多
There exist three problems in the calculation of lateral vibration of the train-track time-variant system athome and abroad and the method to solve them is presented. Spatially coupling vibration analysis model of tra...There exist three problems in the calculation of lateral vibration of the train-track time-variant system athome and abroad and the method to solve them is presented. Spatially coupling vibration analysis model of train-track time-variant system is put forward. Each vehicle is modeled as a multi-body system with 26 degrees of freedomand the action of coupler is also considered. The track structure is modeled as an assembly of track elements with 30degrees of freedom, then the spatially coupling vibration matrix equation of the train-track time-variant system is es-tablished on the basis of the principle of total potential energy with stationary value and the "set-in-right-position"rule. The track vertical geometric irregularity is considered as the excitation source of the vertical vibration of thesystem, and the hunting wave of car bogie frame is taken as the excitation source of lateral vibration of the system.The spatially coupling vibration matrix equation of the system is solved by Wilson-θ direct integration method. Theapproximation of the calculated results to the spot test results demonstrates the feasibility and effectiveness of thepresented analysis method. Finally, some other vibration responses of the system are also obtained.展开更多
为了探究不同含冰率下的有砟道床在列车循环荷载作用下的沉降特性,采用平行黏结模型模拟道砟-冰和冰-冰的黏结作用,建立了不同含冰率下的冰冻有砟道床细观仿真模型,基于离散元法(Discrete Element Method,DEM)与多体动力学(Multi-Body D...为了探究不同含冰率下的有砟道床在列车循环荷载作用下的沉降特性,采用平行黏结模型模拟道砟-冰和冰-冰的黏结作用,建立了不同含冰率下的冰冻有砟道床细观仿真模型,基于离散元法(Discrete Element Method,DEM)与多体动力学(Multi-Body Dynamics,MBD)双向耦合(DEM-MBD)数值模拟,对冰冻道床施加了500次列车循环荷载,对道床宏观上的累积沉降,微观上的冰结键状态,颗粒运动,道砟颗粒力链传递及分布进行了分析。结果表明,高含冰率能显著抑制有砟道床沉降,并呈现“快速沉降-基本稳定”两阶段特征;同时,随着含冰率增加,冰冻作用使道床内部的传力体系从“均匀颗粒力链”向“黏结块状体力链”演变,但也应注意含冰率超过20%时,冰冻有砟道床开始凸显“脆性”。本研究成果丰富了列车循环荷载下冰冻有砟道床沉降特性的研究,并对指导寒区铁路有砟道床运维养护具有参考价值。展开更多
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.52008404,U1934217 and 11790283)Science and Technology Research and Development Program Project of China Railway Group Limited(Major Special Project,No.2020-Special-02)the National Natural Science Foundation of Hunan Province(Grant No.2021JJ30850).
文摘In this work,a method is put forward to obtain the dynamic solution efficiently and accurately for a large-scale train-track-substructure(TTS)system.It is called implicit-explicit integration and multi-time-step solution method(abbreviated as mI-nE-MTS method).The TTS system is divided into train-track subsystem and substruc-ture subsystem.Considering that the root cause of low effi-ciency of obtaining TTS solution lies in solving the alge-braic equation of the substructures,the high-efficient Zhai method,an explicit integration scheme,can be introduced to avoid matrix inversion process.The train-track system is solved by implicitly Park method.Moreover,it is known that the requirement of time step size differs for different sub-systems,integration methods and structural frequency response characteristics.A multi-time-step solution is pro-posed,in which time step size for the train-track subsystem and the substructure subsystem can be arbitrarily chosen once satisfying stability and precision demand,namely the time spent for m implicit integral steps is equal to n explicit integral steps,i.e.,mI=nE as mentioned above.The numeri-cal examples show the accuracy,efficiency,and engineering practicality of the proposed method.
基金Project (50078006) supported by the National Natural Science Foundation of China Project (2001G029) supported by the Foundation of the Science and Technology Section of the Railway Bureau
文摘There exist three problems in the calculation of lateral vibration of the train-track time-variant system athome and abroad and the method to solve them is presented. Spatially coupling vibration analysis model of train-track time-variant system is put forward. Each vehicle is modeled as a multi-body system with 26 degrees of freedomand the action of coupler is also considered. The track structure is modeled as an assembly of track elements with 30degrees of freedom, then the spatially coupling vibration matrix equation of the train-track time-variant system is es-tablished on the basis of the principle of total potential energy with stationary value and the "set-in-right-position"rule. The track vertical geometric irregularity is considered as the excitation source of the vertical vibration of thesystem, and the hunting wave of car bogie frame is taken as the excitation source of lateral vibration of the system.The spatially coupling vibration matrix equation of the system is solved by Wilson-θ direct integration method. Theapproximation of the calculated results to the spot test results demonstrates the feasibility and effectiveness of thepresented analysis method. Finally, some other vibration responses of the system are also obtained.
文摘为了探究不同含冰率下的有砟道床在列车循环荷载作用下的沉降特性,采用平行黏结模型模拟道砟-冰和冰-冰的黏结作用,建立了不同含冰率下的冰冻有砟道床细观仿真模型,基于离散元法(Discrete Element Method,DEM)与多体动力学(Multi-Body Dynamics,MBD)双向耦合(DEM-MBD)数值模拟,对冰冻道床施加了500次列车循环荷载,对道床宏观上的累积沉降,微观上的冰结键状态,颗粒运动,道砟颗粒力链传递及分布进行了分析。结果表明,高含冰率能显著抑制有砟道床沉降,并呈现“快速沉降-基本稳定”两阶段特征;同时,随着含冰率增加,冰冻作用使道床内部的传力体系从“均匀颗粒力链”向“黏结块状体力链”演变,但也应注意含冰率超过20%时,冰冻有砟道床开始凸显“脆性”。本研究成果丰富了列车循环荷载下冰冻有砟道床沉降特性的研究,并对指导寒区铁路有砟道床运维养护具有参考价值。
