Decoupling Capability of Levitation Frames for Medium-Low Speed Maglev Trains

2021 ◽  
pp. 2150178
Author(s):  
Junxiong Hu ◽  
Weihua Ma ◽  
Shihui Luo ◽  
Wan Liu ◽  
Tianwei Qu ◽  
...  
Keyword(s):  
Structural Parameters ◽  
Stability Control ◽  
Test Method ◽  
Air Spring ◽  
Low Speed ◽  
End Set

Medium-low speed maglev trains (MSMTs) with a levitation gap of only 8–10[Formula: see text]mm need an adequate decoupling capability on the levitation frames to ensure stability control in levitation, while preventing the train from rolling sideways when in landing. Based on the geometric and kinematic relationships, two types of levitation frames are studied, i.e. levitation frame with end-set air spring (LFEAS) and levitation frame with mid-set air spring (LFMAS). For each levitation frame, the decoupling process and mechanism are analyzed, the analytical equations for the kinematic attitude are derived, the decoupling capability under different excitations is calculated, along with the effect of various structural parameters assessed. In addition, a test method is designed for the rolling of the levitation frame, particularly with the anti-rolling capability of the LFMAS measured. The results indicate that oscillation of the hanger rods and anti-rolling beams can compensate for displacement when the motion of the levitation frame is decoupled, which is the key to the decoupling capability. Also, the position of the anti-rolling devices and the length of hanger rods do not affect significantly the decoupling capability. However, a longer anti-rolling beam is more conducive to decoupling, but it does not affect the anti-rolling capacity of the levitation frame. The maximum roll computed of the LFMAS is 2.84[Formula: see text]mm, which meets the anti-rolling requirement.

Experimental study on vertical vibration characteristics of medium-low speed maglev vehicle when standing still on steel beams

2021 ◽  
pp. 095440972110324
Author(s):  
Miao Li ◽  
Xiaohao Chen ◽  
Shihui Luo ◽  
Weihua Ma ◽  
Cheng Lei ◽  
...  
Keyword(s):  
Coupled System ◽  
Vertical Vibration ◽  
Vibration Characteristics ◽  
Steel Beams ◽  
Steel Beam ◽  
Air Spring ◽  
Low Speed ◽  
Maglev Vehicle ◽  
Excited Vibration ◽  
Eigen Frequencies

Levitation stability is the very basis for the dynamic operation of Electromagnetic Suspension (EMS) medium-low speed maglev trains (MSMT). However, self-excited vibration tends to occur when the vehicle is standing still above the lightweight lines, which remains a major constraint to the promotion of medium-low speed maglev technology. In order to study the vertical vibration characteristics of the coupled system of MSMT when it is standing still above lightweight lines, levitation tests were carried out on two types of steel beams: steel beam and active girder of the turnout, with a newly developed maglev vehicle using levitation frames with mid-set air spring. Firstly, modal tests were carried out on the steel beam to determine its natural vibration characteristics; secondly, the acceleration signals and the dynamic displacement signals of the air spring obtained at each measurement point were analyzed in detail in both the time and frequency domains, and the vertical ride comfort was assessed by means of the calculated Sperling index. Subsequently, theoretical explanations were given for the occurrence of self-excited vibration of coupled system from the perspective of the vehicle-to-guideway vibration energy input. Results show that the eigen frequencies of the vehicle on the steel beam and the turnout are 9.65 Hz and 2.15 Hz, respectively, the former being close to the natural frequency of the steel beam while the latter being close to the natural frequency of the air spring suspension system, thus causing the self-excited vibration of the coupled system. It is recommended to either avoid the main eigen frequencies of the coupled system or to increase the damping of the corresponding vibration modes to guarantee a reliable coupled system for its long-term performance. These results may provide valuable references for the optimal design of medium-low speed maglev systems.

A refined stiffness model of rolling lobe air spring with structural parameters and the stiffness characteristics of rubber bellows

Measurement ◽  
2021 ◽  
Vol 169 ◽  
pp. 108355
Author(s):  
Jun-Jie Chen ◽  
Zhi-Hong Yin ◽  
Xian-Ju Yuan ◽  
Guang-Qi Qiu ◽  
Kong-Hui Guo ◽  
...  
Keyword(s):  
Structural Parameters ◽  
Air Spring ◽  
Stiffness Model ◽  
Stiffness Characteristics

A novel tripped rollover prevention system for commercial trucks with air suspensions at low speeds

2017 ◽  
Vol 232 (11) ◽  
pp. 1516-1527 ◽  
Author(s):  
Haitao Ding ◽  
Amir Khajepour ◽  
Yanjun Huang
Keyword(s):  
Road Safety ◽  
Commercial Vehicles ◽  
Dynamics Model ◽  
Air Spring ◽  
Severe Injuries ◽  
Low Speed ◽  
Suspension Systems ◽  
Rollover Prevention ◽  
Air Suspension ◽  
Prevention System

This paper presents a novel system to avoid tripped rollovers at low-speed operations for commercial vehicles with air suspension systems. This is of particular significance since truck rollovers have become a serious road safety problem, which usually lead to severe injuries and fatalities. Several active anti-rollover systems have been proposed in the past two decades; however, most of them focus on untripped rollover prevention instead of the tripped rollovers. Up to now, very few pieces of literature discuss the approaches that are used to avoid tripped rollovers of trucks. Furthermore, the air suspension is widely used for commercial vehicles, thus it provides an opportunity to prevent rollovers when properly manipulated. Therefore, a novel tripped rollover prevention system is proposed for trucks at low-speed operations with air suspensions. A roll dynamics model with an air spring is built to investigate the dynamic behavior and the time response of the whole system. More importantly, the feasibility of this new anti-rollover system is discussed and verified by the co-simulations in TruckSim and MATLAB/Simulink under two possible tripped rollover conditions.

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