Secondary Damping Research Articles

Effect of the Magnetorheological Damper Dynamic Behaviour on the Rail Vehicle Comfort: Hardware-in-the-Loop Simulation

Many publications show that the ride comfort of a railway vehicle can be significantly improved using a semi-active damping control of the lateral secondary dampers. However, the control efficiency depends on the selection of the control algorithm and the damper dynamic behaviour, i.e., its force rise response time, force drop response time and force dynamic range. This paper examines the influence of these parameters of a magnetorheological (MR) damper on the efficiency of S/A control for several control algorithms. One new algorithm has been designed. Hardware-in-the-loop simulation with a real magnetorheological damper has been used to get close to reality. A key finding of this paper is that the highest efficiency of algorithms is not achieved with a minimal damper response time. Furthermore, the force drop response time has been more important than the force rise response time. The Acceleration Driven Damper Linear (ADD-L) algorithm achieves the highest efficiency. A reduction in vibration of 34% was achieved.

Modelling and Analysis of Power-Regenerating Potential for High-Speed Train Suspensions

Sustainable technologies in transport systems have attracted significant research efforts over the last two decades. One area of interest is self-powered devices, which reduce system integration complexity and cost with an undoubtedly great potential for improving adaptability and developing sustainability in railway transport systems. One potential solution is a regenerative suspension system, which enables the suspension movements and dissipated energy to be converted into useful electricity. This paper explores the application of hydraulic–electromagnetic regenerative dampers (HERDs) under realistic railway operating conditions for a high-speed train (HST). A vehicle-track-coupled dynamics model is employed to evaluate the regenerative power potential of an HST suspension over a range of operating conditions. The work considers typical route curvature and track irregularity of a high-speed line and speed profile. It was found that power could be regenerated at a level of up to 5–30 W and 5–45 W per generation unit when fitted to the primary and secondary dampers, respectively. Such power-regeneration levels were adequate to supply a variety of low-power-consumption onboard components such as warning lights and wireless sensors. Further analysis of the carbody loading level also was carried out. The analysis revealed that, in the case of a high-speed journey, poor track geometry, low curvature, and reduced carbody weight increased the quantity of regenerative energy harvested by the HERDs. It was concluded that a suitable HERD design could be achieved that could facilitate the development of a smart railway damper that includes both self-sensing and power-generation functions.

Combustion Optimization Test of “W” Flame Furnace Based on Orthogonal Experimental Design

This paper focuses on the selection ideas, test methods, test results and analysis of a “W” type flame furnace combustion test program. Under the electrical load of 300MW, 250MW, 200MW and 150MW, the orthogonal test method is adopted to change the “furnace outlet oxygen amount”, “secondary wind and grading wind distribution mode”, “burning air opening degree”, “secondary damper combination method” and “heat load distribution” of the boiler so as to make clear about the impact of various operating conditions on boiler efficiency and NOx emission level, and summarize the optimal operation mode of the boiler. The combustion adjustment can improve the economic and environmental protection of the boiler under different working conditions, which provides data support for equipment safety, environmental protection and economic operation, and provides reference for boiler combustion optimization test research and combustion optimization of the same type of furnace.

Cross-Sectional Shape Optimization of Secondary Damper Oil Seal for Rolling Stock

Cross-Sectional Shape Optimization of Secondary Damper Oil Seal for Rolling Stock

Research on the city tram collision at a level crossing

The collision simulation between a city tram and a car at a level crossing is carried out based on the multi-body dynamics. Compared with the finite element method, this method has an obvious advantage of fast computation speed, so that it is convenient for the study on the dynamic responses and derailment mechanism of railway vehicles during a collision accident. The simulation results show that when a city tram is laterally impacted by a car at a level crossing, the dynamic response and the derailment risk of the collided city tram are greatly influenced by the boundary conditions, such as the mass and speed of the colliding car, the structural arrangement and the loading condition of the city tram. Moreover, in terms of the space limitation of the city tram, two measures are proposed to decrease the lateral impact force during its transition from car body to wheel set. One is to use the secondary damper and the other is to increase the secondary lateral clearance. The simulation results point out that the derailment coefficient of the improved city tram can be reduced by 52%, from 1.63 to 0.79.

Comparison Study of Vibration Control Effects between Suspended Tuned Mass Damper and Particle Damper

The vibration control performance and its influencing factors of a tuned mass damper and a particle damper are examined by a single degree of freedom structure with such devices. The vibration control effects between these two dampers are also investigated. Increasing the mass ratio of the damper can improve the damping effects; under the condition of tuning frequency, the damping effects are remarkable. However, the more the deviation from the tuned frequency, the less controlling effects can be obtained. The damping effect of a particle damper is generally better than that of a tuned mass damper. For this test model, the particle damper can improve primary structure’s equivalent damping ratio 19 times to the original one’s, while the tuned mass damper can be 13 times. The reason lies in the fact that the particle damper can dissipate input energy by tuning mass, collision, impact, and friction between particles and the container and the momentum exchange effects between the secondary damper mass and the primary structure.

Optimum secondary dampers for free response of underdamped systems

While the problem of vibration absorption of forced response of linear systems has received considerable treatment, the case of free response has not been studied adequately. This paper is concerned with the case of transient response of damped systems. Because the original vibrating system cannot usually be altered, a conventional plan of attack has been attaching a vibration absorber system to it. In the technique discussed here, this strategy is followed and a problem is formulated of finding the optimum parameters of such a secondary system so that the magnitude of the response of the combined system will be reduced. However, because of the complexity of the form of the ensuing mathematical programming problem, an analytical solution is not possible. Instead, the problem can be solved by employing a numerical optimization algorithm to be implemented by the digital computer. The results are presented in the form of comprehensive design tables that can be readily used by designers since the parameters are given in terms of dimensionless varibles. These results show that the addition of the absorber system can be effective only when the amount of damping in the original system is lower than a certain limit. They also show that, when the damping of the original system is low, the attachment of the damper is remarkably effective and beneficial.

Damping Increase in Building with Tuned Mass Damper

The Sydney Tower, the tallest building in Australia, is 820ft (250m) high and with the base of the structure anchored on the roof of a 15 storey building, it stands 1000ft (305m) above street level. The tower is one of the first buildings with the installation of a large scale tuned mass damper (TMD). The doughnut-shaped water tank near the top of the turret, which normally serves as the tower’s water and fire protection supply, was incorporated into the design of the TMD to reduce wind-induced motions. Energy associated with relative movements between the tower and the water tank is dissipated by 8 shock-absorbers installed tangentially to the tank and anchored to the floor of the turret. A secondary TMD of similar design was later installed on the intermediate anchorage ring to further increase the damping level, particularly in the second mode. Full scale measurements were taken to determine the natural frequencies of vibration and damping. Dampings of the tower were determined for different damper configurations. The natural frequencies of vibration were found to be 0.10 Hz and 0.50 Hz for the first mode and second mode respectively. Significant increases in damping levels, particularly in second mode, are produced by the water tank tuned mass damper and the secondary damper.

Full-scale measurements of wind-induced response of Sydney Tower

Results of full-scale measurements of wind-induced response of Sydney Tower taken between December 1980 and August 1982 are presented in this paper. The natural frequencies of vibration were found to be 0.10 Hz and 0.50 Hz for the first mode and second mode respectively. Significant increases in damping levels, particularly in the second mode, are produced by the water tank tuned-mass damper and the secondary damper. After the installation of the secondary damper, there were noticeable reductions in the peak along-wind and cross-wind acceleration responses. At moderate wind speeds, the total and first mode component of response were essentially normally distributed, but non-Gaussian characteristics were evident in the second mode response.