• Smart Structures and Systems
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• v.18 no.1
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• pp.53-74
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• 2016

This paper presents an experimental study on constructing a tunable secondary suspension for high-speed trains using magneto-rheological fluid dampers (referred to as MR dampers hereafter), in the interest of improving lateral ride comfort. Two types of MR dampers (type-A and type-B) with different control ranges are designed and fabricated. The developed dampers are incorporated into a secondary suspension of a full-scale high-speed train carriage for rolling-vibration tests. The integrated rail vehicle runs at a series of speeds from 40 to 380 km/h and with different current inputs to the MR dampers. The dynamic performance of the two suspension systems and the ride comfort rating of the rail vehicle are evaluated using the accelerations measured during the tests. In this way, the effectiveness of the developed MR dampers for attenuating vibration is assessed. The type-A MR dampers function like a stiffness component, rather than an energy dissipative device, during the tests with different running speeds. While, the type-B MR dampers exhibit significant damping and high current input to the dampers may adversely affect the ride comfort. As part of an ongoing investigation on devising an effective MR secondary suspension for lateral vibration suppression, this preliminary study provides an insight into dynamic behavior of high-speed train secondary suspensions and unique full-scale experimental data for optimal design of MR dampers suitable for high-speed rail applications.

• Fire Science and Engineering
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• v.28 no.5
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• pp.30-36
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• 2014

The pressurized smoke control system in the vestibule is important for fire safety in buildings because it is concerned with egress time of people and the safety of fire fighters. The vestibule pressurization system can prevent smoke from entering the vestibule using differential pressure when fire doors are closed and using the egress velocity when fire doors are open. Air supplying units in the vestibule need to be arranged by taking account of the location of doors and the volume of the vestibule in order to assure the uniform air egress velocity through a fire door when it is open. In this study, computational fluid dynamics (CFD) simulations were conducted for the vestibule where multiple doors are installed and it was found that the reverse flow occurs when the damper position in vestibule is not appropriate.