Based on 3D, steady N-S equations and k-e turbulence model, Fluent was employed to do numerical simulation for lateral aerodynamic performance of 6-axis X2K double-deck container trains with two different loading form...Based on 3D, steady N-S equations and k-e turbulence model, Fluent was employed to do numerical simulation for lateral aerodynamic performance of 6-axis X2K double-deck container trains with two different loading forms, and speed limits of the freight trains were studied. The result indicates that under wind environment： 1） As for vehicles without and with cross-loaded structure, aero-pressure on the former is bigger, but air velocity around the latter is larger; 2） When sideslip angle θ=0°, the airflow is symmetry about train vertical axis; when θ〉0°, the airflow is detached at the top of vehicles, and the air velocity increases above the separated line but decreases below it; 3） With θ increasing, the lateral force on the mid vehicle firstly increases but decreases as θ=75°; 4） When the 6-axis X2K fiat car loads empty boxes of a 40 ft and a 48 ft at 120 km/h, the overturning wind speed is 25.19 m/s, and the train should be stopped under the 12th grade wind speed.展开更多
The Newton Raphson iteration and QR algorithm are combined to search the Hpf bifurcation point of the vehicle running on straight track and on large radius curved tracks. Limit cycles that are bifurcated from the equ...The Newton Raphson iteration and QR algorithm are combined to search the Hpf bifurcation point of the vehicle running on straight track and on large radius curved tracks. Limit cycles that are bifurcated from the equilibrium points and the saddle node bifurcation point are computed through employing a variable step Runge Kutta method and the Poincaré map. Finally, numerical simulations are carried out for the stability of a high speed passenger car operating on straight and large radius curved tracks. The influences of the radius of curvature and the superelevation of the track on the stability of the vehicle system are investigated.展开更多
针对车门内板成形过程中出现的局部开裂问题,通过综合应用试验法和Auto Form有限元仿真技术,基于正交试验法实现快速定位影响车门内板成形缺陷的主要工艺参数;分析了主要工艺参数对车门内板成形性的影响规律,以此为依据对车门内板冲压...针对车门内板成形过程中出现的局部开裂问题,通过综合应用试验法和Auto Form有限元仿真技术,基于正交试验法实现快速定位影响车门内板成形缺陷的主要工艺参数;分析了主要工艺参数对车门内板成形性的影响规律,以此为依据对车门内板冲压工艺参数进行调整,现场开展零件试制,获取零件应变情况。结果表明,影响车门内板危险区最大减薄率的主要因素为摩擦系数和压边力;随着摩擦系数和压边力的增大,破裂风险处的减薄率提高;当压边力控制在900~1100 k N范围内,摩擦系数控制在0.09~0.12时,成形结果较好;经过对车门内板进行冲压工艺参数调整,未出现开裂情况,原来开裂区域的安全裕度均大于10%,符合生产要求。展开更多
基金Project supported by Scholarship Award for Excellent Doctoral Student granted by Ministry of Education,ChinaProject(2012QNZT029) supported by the Fundamental Research Funds for the Central Universities of China+1 种基金Project(CX2010B122) supported by Hunan Provincial Innovation Foundation for Postgraduate,ChinaProject(2010ybfz088) supported by the Foundation of Excellent Doctoral Dissertation of Central South University,China
文摘Based on 3D, steady N-S equations and k-e turbulence model, Fluent was employed to do numerical simulation for lateral aerodynamic performance of 6-axis X2K double-deck container trains with two different loading forms, and speed limits of the freight trains were studied. The result indicates that under wind environment： 1） As for vehicles without and with cross-loaded structure, aero-pressure on the former is bigger, but air velocity around the latter is larger; 2） When sideslip angle θ=0°, the airflow is symmetry about train vertical axis; when θ〉0°, the airflow is detached at the top of vehicles, and the air velocity increases above the separated line but decreases below it; 3） With θ increasing, the lateral force on the mid vehicle firstly increases but decreases as θ=75°; 4） When the 6-axis X2K fiat car loads empty boxes of a 40 ft and a 48 ft at 120 km/h, the overturning wind speed is 25.19 m/s, and the train should be stopped under the 12th grade wind speed.
文摘The Newton Raphson iteration and QR algorithm are combined to search the Hpf bifurcation point of the vehicle running on straight track and on large radius curved tracks. Limit cycles that are bifurcated from the equilibrium points and the saddle node bifurcation point are computed through employing a variable step Runge Kutta method and the Poincaré map. Finally, numerical simulations are carried out for the stability of a high speed passenger car operating on straight and large radius curved tracks. The influences of the radius of curvature and the superelevation of the track on the stability of the vehicle system are investigated.
文摘针对车门内板成形过程中出现的局部开裂问题,通过综合应用试验法和Auto Form有限元仿真技术,基于正交试验法实现快速定位影响车门内板成形缺陷的主要工艺参数;分析了主要工艺参数对车门内板成形性的影响规律,以此为依据对车门内板冲压工艺参数进行调整,现场开展零件试制,获取零件应变情况。结果表明,影响车门内板危险区最大减薄率的主要因素为摩擦系数和压边力;随着摩擦系数和压边力的增大,破裂风险处的减薄率提高;当压边力控制在900~1100 k N范围内,摩擦系数控制在0.09~0.12时,成形结果较好;经过对车门内板进行冲压工艺参数调整,未出现开裂情况,原来开裂区域的安全裕度均大于10%,符合生产要求。
