Railway & Rolling stock
There is a wide range of vibration and noise phenomena surrounding rail transport. It may affect the community, the comfort on the train, but also the reliability of the rolling stock.
Rail-wheel noise emission is a main concern for any location worldwide. And there is clear progress. Still, the implementation of best practices and further research on solutions are essential. This is worthwhile because the combination of steel wheels and rail remain the most energy efficient solution in ground transportation, regardless whether it is for goods or commuting.
The improvements in noise comfort in modern rolling stock is impressive. And it is not easy because sturdiness, reliability, limited weight and limiting costs pose challenges and require constant proof that improvements to control the noise and vibration are required.
The acoustic quality inside the rain also requires some attention, bare cabins with high reverberation levels and insufficient muffling of conversations are unpleasant even on low speed commuter trains and street cars.
And there are other issues related to vibration and noise affecting the environment, the comfort, the reliability, and the image of trains and rail infrastructure. Many of the artificial excitation solutions we provide are especially effective in the railway domain.
Some Applications
Rail input accelerance/ impedance, and rail/bridge vibro-acoustic transfer measurements
On bridges, comparing sleeper, clamping and bed solutions, for research, for model correlation etc.
The below Qsources shakers make such measurements more efficient and accurate: (from low to high frequency and high to lower force level)
Mid-high frequency airborne noise isolation
Many issues in the cabins are related to medium and high frequency airborne isolation. Energy based methods are most common. Many components on the body, from sealing to windows to compartment doors, all influence the isolation. And the following sound sources support efficient measurements:
(from low to high frequency and high to lower sound power level)
Low-mid frequency airborne interior noise
At low-mid frequencies energy methods may fail to address amplification effects due to standing waves or specific modes in the cabin or panels. For the lower frequencies we propose volume sound sources, monopoles, for airborne room transfer, airborne isolation, vibro-acoustic transfer. The following sound sources support efficient measurements: (from low to high frequency and high to lower sound power level)
Train structure borne noise isolation
At lower frequencies structure borne transfer into the cabin starts to dominate. It is possible quantify the vibro-acoustic transfer from boogie (Or motor, pantograph, or ventilation etc.) attachments to the coach to interior noise at passenger ear locations. This could be done by microphones and shaker structural excitation:
Or the vibro-acoustic transfer can be measured reciprocally with a volume sound source and accelerometers at the attachment locations like:
Vibration and low frequency noise comfort, modal analysis
There are various significant low frequency disturbances like rail input, wheel unbalance, panthograph vibration. When eigen-modes coincide with an unbalance, or an aerodynamic Strouhal frequency, amplification occurs and the cabin comfort is seriously affected. Analysis of the modes of the coach, bogie, roof panels, etc. etc. helps prevent excessive sensitivity. Various Qsources shakers make such measurements more efficient and more accurate. But it even allows measurements on complete operation-ready trains which was previously impossible or too unpractical. Shaker solution from low to higher frequencies:
