AbstractMulti-Directional Tuned Mass Damper (MDTMD) was invented in Hong Kong for railway noise control and
patented in a few countries in 2008. It uses thin rubber layers to perform shearing direction Tuned Mass
Damping (TMD) for both vertical and lateral rail vibrations. It provides >10dB vibration reduction and 3 to
6dB(A)noise reduction subject to other noise sources. This invention provides a breakthrough to control
high-frequency TMD (>300Hz). In addition, MDTMD is the world’s only damper able to slow down
corrugation growth rate by half when corrugation frequency is matched with the TMD frequency. Five damper
generations with different designs on mounting structure, interface layer and oscillation mass have been
tested since 2010. For optimization on installation, maintenance, durability, manufacturability and
performance, the 5th generation employs 10 circular-shape oscillation masses.
For cyclic-motion vibration, TMD is employed to dissipate vibration energy with loss factors between 12% and
25%. Recent test indicates that half damper installation MDTMD (1 damper per 2 spaces) can also provide
noise reduction of 3 to 6dB(A), which would be the 1st report on noise reduction performance of half damper
installation. Besides, the 5th generation MDTMD has a variation design for light rail noise reduction and half
damper installation on light rail will be installed and tested in Zurich in summer 2018.
SpeakerWilson Ho is the founder of Wilson Acoustics Limited, specialized in railway trackform noise and vibration
control, TBM groundborne noise assessment, construction noise control, PA system acoustic design and
acoustic expert witness. He invented MDTMD in 2008 for railway noise control and retractable noise barrier in
2014 for construction noise control. He has made significant contributions to the noise control development of
the new railway lines in Hong Kong.
Registration (first-come first-served)Please register before 23 April 2018 via the link
http://www.wal.hk/hkioa/raildamper. The seminar is free of
charge for HKIOA members, PolyU students and staff, and members of the supporting organizations. Other
interested persons could attend the seminar by paying HK$100 registration fee.