To analyze the dynamic response and reliability of a continuous beam bridge under the action of an extra heavy vehicle, a vehicle–bridge coupled vibration model was established based on the virtual work principle and...To analyze the dynamic response and reliability of a continuous beam bridge under the action of an extra heavy vehicle, a vehicle–bridge coupled vibration model was established based on the virtual work principle and vehicle–bridge displacement compatibility equation, which can accurately simulate the dynamic characteristics of the vehicle and bridge. Results show that deck roughness has an important function in the effect of the vehicle on the bridge. When an extra heavy vehicle passes through the continuous beam bridge at a low speed of 5 km/h, the impact coefficient reaches a high value, which should not be disregarded in bridge safety assessments. Considering that no specific law exists between the impact coefficient and vehicle speed, vehicle speed should not be unduly limited and deck roughness repairing should be paid considerable attention. Deck roughness has a significant influence on the reliability index, which decreases as deck roughness increases. For the continuous beam bridge in this work, the reliability index of each control section is greater than the minimum reliability index. No reinforcement measures are required for over-sized transport.展开更多
Continuous transient impact(CTI)frequently occurs in power split(PS)hybrid powertrain system when the mode transition torque crossing zero,which affects overall vehicle ride comfort.To study the CTI mechanism,a transi...Continuous transient impact(CTI)frequently occurs in power split(PS)hybrid powertrain system when the mode transition torque crossing zero,which affects overall vehicle ride comfort.To study the CTI mechanism,a transient torsional vibration(TTV)coupling model of a hybrid powertrain test system is established based on the test bench with double feedforward correction load emulation compensation control,and realize the CTI performance prediction along the power transfer path.Firstly,the time-domain and frequency-domain characteristics of CTI during the mode transition process(MTP)test are introduced.Secondly,the external excitation model including bench load,engine resistance torque and motor torque ripple,and the internal excitation model including the torsional vibration of planetary coupling(PC)and two stage reducer are established.Then,the MTP coordinated control method of power split hybrid powertrain test system are introduced,and the gear torque zero crossing model which considering time-varying stiffness,damping and gear backlash is integrated into the TTV model.Finally,the CTI mechanism is simulated and analyzed.The results show that the front planet gear of Ravigneaux-PC is the main source of high-frequency gear knocking.Moreover,the frequent torque crossing zero at the dedicated hybrid transmission(DHT)power output end after the torque coordinated control of each power source is the main cause of continuous mesh impact during MTP,and the coupling effect with the gear backlash intensifies the CTI of DHT output end at frequency band 100–200 Hz,and the CTI can reduce the overall efficiency of PS-DHT system and vehicle comfort.The research results are useful for the development of CTI suppression optimization algorithm.展开更多
基金Project(50779032)supported by the National Natural Science Foundation of ChinaProject(20090451330)supported by the Postdoctoral Foundation of ChinaProject(BS2013SF007)supported by Shandong Scientific Research Award Foundation for Outstanding Young Scientists,China
文摘To analyze the dynamic response and reliability of a continuous beam bridge under the action of an extra heavy vehicle, a vehicle–bridge coupled vibration model was established based on the virtual work principle and vehicle–bridge displacement compatibility equation, which can accurately simulate the dynamic characteristics of the vehicle and bridge. Results show that deck roughness has an important function in the effect of the vehicle on the bridge. When an extra heavy vehicle passes through the continuous beam bridge at a low speed of 5 km/h, the impact coefficient reaches a high value, which should not be disregarded in bridge safety assessments. Considering that no specific law exists between the impact coefficient and vehicle speed, vehicle speed should not be unduly limited and deck roughness repairing should be paid considerable attention. Deck roughness has a significant influence on the reliability index, which decreases as deck roughness increases. For the continuous beam bridge in this work, the reliability index of each control section is greater than the minimum reliability index. No reinforcement measures are required for over-sized transport.
基金funded by National Natural Science Foundation of China,under grand number 51675381Science and Technology Innovation Plan Of Shanghai Science and Technology Commission under grand number 21DZ1209700.
文摘Continuous transient impact(CTI)frequently occurs in power split(PS)hybrid powertrain system when the mode transition torque crossing zero,which affects overall vehicle ride comfort.To study the CTI mechanism,a transient torsional vibration(TTV)coupling model of a hybrid powertrain test system is established based on the test bench with double feedforward correction load emulation compensation control,and realize the CTI performance prediction along the power transfer path.Firstly,the time-domain and frequency-domain characteristics of CTI during the mode transition process(MTP)test are introduced.Secondly,the external excitation model including bench load,engine resistance torque and motor torque ripple,and the internal excitation model including the torsional vibration of planetary coupling(PC)and two stage reducer are established.Then,the MTP coordinated control method of power split hybrid powertrain test system are introduced,and the gear torque zero crossing model which considering time-varying stiffness,damping and gear backlash is integrated into the TTV model.Finally,the CTI mechanism is simulated and analyzed.The results show that the front planet gear of Ravigneaux-PC is the main source of high-frequency gear knocking.Moreover,the frequent torque crossing zero at the dedicated hybrid transmission(DHT)power output end after the torque coordinated control of each power source is the main cause of continuous mesh impact during MTP,and the coupling effect with the gear backlash intensifies the CTI of DHT output end at frequency band 100–200 Hz,and the CTI can reduce the overall efficiency of PS-DHT system and vehicle comfort.The research results are useful for the development of CTI suppression optimization algorithm.
