Experiment and dynamic simulation were combined to obtain the loads on bicycle frame. A dynamic model of body-bicycle system was built in ADAMS. Then the body gestures under different riding conditions were captured b...Experiment and dynamic simulation were combined to obtain the loads on bicycle frame. A dynamic model of body-bicycle system was built in ADAMS. Then the body gestures under different riding conditions were captured by a motion analysis system. Dynamic simulation was carried out after the data of body motions were input into the simulation system in ADAMS and a series of loads that the body applied on head tube, seat pillar and bottom bracket were obtained. The results show that the loads on flame and their distribution are apparently different under various riding conditions. Finally, finite element analysis was done in ANSYS, which showed that the stress and its distribution on frame were apparently different when the flame was loaded according to the bicycle testing standard and simulation respectively. An efficient way to obtain load on bicycle flame accurately was proposed, which is sig- nificant for the safety of cycling and will also be the basis for the bicycle design of digitalization, lightening and cus- tomization.展开更多
A high-speed train-track coupling dynamic model is used to investigate the dynamic behavior of a high-speed train operating on a curved track with failed fasteners. The model considers a high-speed train consisting of...A high-speed train-track coupling dynamic model is used to investigate the dynamic behavior of a high-speed train operating on a curved track with failed fasteners. The model considers a high-speed train consisting of eight vehicles coupled with a ballasted track. The vehicle is modeled as a multi-body system, and the rail is modeled with a Timoshenko beam resting on the discrete sleepers. The vehicle model considers the effect of the end connections of the neighboring vehicles on the dynamic behavior. The track model takes into account the lateral, vertical, and torsional deformations of the rails and the effect of the discrete sleeper support on the coupling dynamics of the vehicles and the track. The sleepers are assumed to move backward at a constant speed to simulate the vehicle running along the track at the same speed. The train model couples with the track model by using a Hertzian contact model for the wheel/rail normal force calculation, and the nonlinear creep theory by Shen et al. (1984) is used for wheel/rail tangent force calculation. In the analysis, a curved track of 7000-m radius with failed fasteners is selected, and the effects of train operational speed and the number of failed fasteners on the dynamic behaviors of the train and the track are investigated in detail. Furthermore, the wheel/rail forces and derailment coefficient and the wheelset loading reduction are analyzed when the high-speed train passes over the curved track with the different number of continuously failed fasteners at different operational speeds. Through the detailed numerical analysis, it is found that the high-speed train can operate normally on the curved track of 7000-m radius at the speeds of 200 km/h to 350 km/h.展开更多
A maneuver control approach using a scissored pair of control moment gyros is proposed to improve the penetration ability of a hypersonic gliding vehicle(HGV) with a relatively high lift-drag ratio. Then, a multivaria...A maneuver control approach using a scissored pair of control moment gyros is proposed to improve the penetration ability of a hypersonic gliding vehicle(HGV) with a relatively high lift-drag ratio. Then, a multivariable strong coupling nonlinear bank-toturn dynamical model is established for the case of lateral maneuvering of an HGV equipped with a scissored pair of control moment gyros. According to the requirement of coordinated turning of the HGV in a lateral maneuver, a decoupling controller based on feedback linearization and a linear quadratic optimal algorithm is designed. Finally, the large airspace maneuvering trajectories of the HGV including S-shaped, cycloid and spiral maneuvering modes are designed by applying overload control technology. Simulations demonstrate that the designed maneuvering trajectory significantly increases the airspace range and flexibility of the vehicle. The coordinated turn control system achieves an accurate and rapid tracking of the maneuvering trajectories in large airspace.展开更多
基金Supported by Special Fund Project for Technology Innovation of Tianjin (No. 10FDZDGX00500)Tianjin Product Quality Inspection Technology Research Institute (No. 11-03)
文摘Experiment and dynamic simulation were combined to obtain the loads on bicycle frame. A dynamic model of body-bicycle system was built in ADAMS. Then the body gestures under different riding conditions were captured by a motion analysis system. Dynamic simulation was carried out after the data of body motions were input into the simulation system in ADAMS and a series of loads that the body applied on head tube, seat pillar and bottom bracket were obtained. The results show that the loads on flame and their distribution are apparently different under various riding conditions. Finally, finite element analysis was done in ANSYS, which showed that the stress and its distribution on frame were apparently different when the flame was loaded according to the bicycle testing standard and simulation respectively. An efficient way to obtain load on bicycle flame accurately was proposed, which is sig- nificant for the safety of cycling and will also be the basis for the bicycle design of digitalization, lightening and cus- tomization.
基金Project supported by the National Natural Science Foundation of China (No. U1134202)the National Basic Research Program (973) of China (No. 2011CB711103)the Program for Changjiang Scholars and Innovative Research Team in University (Nos. IRT1178and SWJTU12ZT01), China
文摘A high-speed train-track coupling dynamic model is used to investigate the dynamic behavior of a high-speed train operating on a curved track with failed fasteners. The model considers a high-speed train consisting of eight vehicles coupled with a ballasted track. The vehicle is modeled as a multi-body system, and the rail is modeled with a Timoshenko beam resting on the discrete sleepers. The vehicle model considers the effect of the end connections of the neighboring vehicles on the dynamic behavior. The track model takes into account the lateral, vertical, and torsional deformations of the rails and the effect of the discrete sleeper support on the coupling dynamics of the vehicles and the track. The sleepers are assumed to move backward at a constant speed to simulate the vehicle running along the track at the same speed. The train model couples with the track model by using a Hertzian contact model for the wheel/rail normal force calculation, and the nonlinear creep theory by Shen et al. (1984) is used for wheel/rail tangent force calculation. In the analysis, a curved track of 7000-m radius with failed fasteners is selected, and the effects of train operational speed and the number of failed fasteners on the dynamic behaviors of the train and the track are investigated in detail. Furthermore, the wheel/rail forces and derailment coefficient and the wheelset loading reduction are analyzed when the high-speed train passes over the curved track with the different number of continuously failed fasteners at different operational speeds. Through the detailed numerical analysis, it is found that the high-speed train can operate normally on the curved track of 7000-m radius at the speeds of 200 km/h to 350 km/h.
基金supported by the Key Laboratory Opening Funding(Grant No.HIT.KLOF.2016.071)
文摘A maneuver control approach using a scissored pair of control moment gyros is proposed to improve the penetration ability of a hypersonic gliding vehicle(HGV) with a relatively high lift-drag ratio. Then, a multivariable strong coupling nonlinear bank-toturn dynamical model is established for the case of lateral maneuvering of an HGV equipped with a scissored pair of control moment gyros. According to the requirement of coordinated turning of the HGV in a lateral maneuver, a decoupling controller based on feedback linearization and a linear quadratic optimal algorithm is designed. Finally, the large airspace maneuvering trajectories of the HGV including S-shaped, cycloid and spiral maneuvering modes are designed by applying overload control technology. Simulations demonstrate that the designed maneuvering trajectory significantly increases the airspace range and flexibility of the vehicle. The coordinated turn control system achieves an accurate and rapid tracking of the maneuvering trajectories in large airspace.
