Classifications

• • E—FIXED CONSTRUCTIONS
  • E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
  • E01B—PERMANENT WAY; PERMANENT-WAY TOOLS; MACHINES FOR MAKING RAILWAYS OF ALL KINDS
  • E01B19/00—Protection of permanent way against development of dust or against the effect of wind, sun, frost, or corrosion; Means to reduce development of noise
  • E01B19/003—Means for reducing the development or propagation of noise

Definitions

• This invention relates to a vibration absorber for reducing vibration and noise radiation from rail, and the fastening mechanism to attach the absorber to the rail.
• the invention is a vibration absorber based on tuned mass damping mechanism, comprising oscillation mass, shear resilient layers and holding plates stacked alternatively to form discrete mass-spring-systems.
• tuned mass damping mechanism comprising oscillation mass, shear resilient layers and holding plates stacked alternatively to form discrete mass-spring-systems.
• the present invention provides a persistent mounting method with rigid connection at the mounting interface for high frequency vibration.
• the absorber is mounted to the rail by compressive force provided by a mounting bolt beneath the rail.
• An inclined plane is used to provide simultaneous clamping forces in both vertical and lateral directions.
• thin layer of gap filing material having high viscosity and low compressibility are applied.
• the gap filling material aims to solidify any movement gaps for high frequency (>300Hz) vibration transmission.
• Resilient buffer layer is inserted above the inclined plane.
• the resilient buffer provides rigid connection for effective energy transfer to the vibration absorbers.
• these resilient buffers prevent structural damage to mounting components. After the event, the mounting members would be automatically restored to its original position by the resilient buffer compression force.
• Fig. 1 shows the cross sectional view of an exemplary embodiment of the vibration absorber being attached to the rail.
• Fig. 2 shows the isometric view of an exemplary embodiment of the vibration absorber being attached to the rail.
• Fig. 3 shows the 3-dimensional view of an exemplary embodiment of the vibration absorber being attached to the rail, as viewed from the bottom.
• Fig. 4 shows another exemplary embodiment of the vibration absorber, in which one oscillation mass is split to form a 2 degree of freedom system.
• Each labeled component is described below:
• the vibration absorber is attached to the rail web 4 and foot tip 3 via the mounting bars 1.
• Gap filling material 2 is applied at the interfaces between the mounting bars and the rail surface.
• Viscous damping material 17 is applied at the mounting interface between viscous layer constraint bar 10 and the bottom surface of the foot tips 3.
• Lateral compression force is exerted by a damper mounting bolt 5 underneath the rail.
• Force orientation bar 7 with an inclined plane 6 is used to change the orientation of the compression force thus allow the device to provide both lateral and vertical mounting force simultaneously.
• the vertical clamping force generated from the force orientation bar would be transferred to the foot tip via the resilient buffer layer 9, its holding plate 15, the viscous layer constraint bar 10 and the viscous damping layer 17.
• the lateral clamping force is transferred to the rail web via the force transmission members 11, oscillation mass holding plates 13 and mounting bars 1.
• An oscillation mass mounting bolt 8 is inserted through the holding plates 13, oscillation resilient layers 14 and oscillation masses 12 alternatively. Nuts are tightened to a specific torque at the two ends of the bolt so as to provide adequate holding force for the oscillation masses to oscillate at prescribed frequencies. Nylon nuts 16 are then tightened onto the top of conventional nuts to prevent them from loosening.
• the invention uses a Force Orientation Bar with an inclined plane.
• the inclined plane transfers the horizontal compression force from the Damper Mounting Bolt to mounting forces in both vertical and horizontal directions. Therefore simultaneous mounting forces can be provided at all mounting points by tightening the Mounting Bolt.
• Vibration displacement of rails at noise radiation frequency is less than a few microns. Movement gaps at the attachment interface would be significantly hinder vibration energy transfer from the rail to the vibration absorbers.
• Existing vibration absorber mounting methods such as clamping and gluing cannot provide satisfactory mounting rigidity. For gluing fixation, sub-micron size gaps in the glue layers are inevitable especially in rusted and greasy operating rails. For clamping fixation, gaps are gradually generated and enlarged at the mounting interfaces by vibration from repeated train passage.
• the present invention uses gap filling material (adhesive material with high viscosity and low compressibility) at the mounting points. Under static compressive force, the material behaves as flexible solid and deformed to fill up the movement gaps at the mounting points. Under high frequency dynamic train excitation force, it behaves as stiff solid which allow vibration energy to be effectively transferred to the absorber.
• gap filling material adheresive material with high viscosity and low compressibility
• Viscous damping material is applied at the interface between the foot tip bottom face and the viscous layer constraint bar to provide viscous damping to the bending waves along the rails.
• the mounting structure may fatigue and the mounting nuts may be loosened, and then the mounting rigidity would be substantially reduced.
• Resilient buffer layers are introduced to provide persistent mounting.
• the nylon nuts have high friction at threads. They are screwed onto the top of conventional steel nuts to prevent loosening of the conventional nuts.
• Resilient buffer layers are inserted above the inclined plane. These resilient layers are pre-compressed to specified ratio (e.g.5 to 25%) by tightening their mounting bolts. For typical rail vibration of less than lOOg, the resilient layer provides rigid connection. In extreme events of high vibrations (>100g), these resilient layers act as a spring buffer to prevent structural damage of mounting components. After the event, the mounting components would be automatically restored to its original position by the resilient buffer layer force.
• the vibration absorber is a tuned mass damper. It comprises of a plurality of oscillation masses. Each oscillation mass in the vibration absorber acts as a discrete single order of freedom (SDOF) mass-spring-system. Their natural frequencies can be independently tuned to match rail vibration at multiple frequencies. Such feature allows design flexibility for absorption of rail vibration at multiple frequencies, as there is no limitation on the frequency tuning for individual oscillation masses. As vibration bending waves propagate along the rail, the vibration energy is transferred to the oscillation masses and dissipated in the oscillation resilient layers by hysteresis.
• SDOF discrete single order of freedom
• the vibration absorber Apart from absorbing rail vibration energy by tuned mass damping, the vibration absorber also indirectly reduces rolling noise by reducing rail corrugation growth rate, as observed in field tests.
• the SDOF system can be converted to multiple degree of freedom (MDOF) systems by splitting the oscillation mass and inserting a resilient layer in between, without the need to alter other components.
• Fig. 4 shows another exemplary embodiment of the vibration absorber having a 2 DOF system. The natural frequencies are given by eqt(l).
• A is the contact area between the resilient layer and the oscillation mass
• K is a constant depends on the splitting geometry and properties of the additional resilient layer Frequency Tuning at Vertical and Lateral Directions
• the present invention allows the oscillation masses to have different vertical and lateral natural frequencies by using anisotropic resilient layers.
• anisotropy may be achieved by introducing wavy patterns at the resilient layer surfaces along one direction.

Landscapes

• Engineering & Computer Science (AREA)
• Architecture (AREA)
• Civil Engineering (AREA)
• Structural Engineering (AREA)
• Vibration Prevention Devices (AREA)
• Railway Tracks (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=44166805

Family Applications (1)

Country Status (3)

Families Citing this family (6)

Family Cites Families (10)

• 2010
  • 2010-11-19 WO PCT/IB2010/055290 patent/WO2011073826A1/en active Application Filing
  • 2010-11-19 EP EP10837137.8A patent/EP2513374A4/de not_active Withdrawn
  • 2010-11-19 CN CN201080056875.3A patent/CN102713066B/zh not_active Expired - Fee Related

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events