Measuring transfer functions of track structures in a test rig with laser Doppler vibrometer and accelerometers on a moving vehicle

A transfer function (TF) is an effective representation of the load-response relationship of railway track structures. To fill the gap in measuring track structure TFs over a wide frequency range from a moving vehicle, we develop a TF measurement system and the associated TF estimation methodology. Accelerometers are utilized to estimate the...

Monitoring Dynamic Properties of Railway Tracks Using Train-borne Vibrometer Measurement

Characterization and Mitigation of Speckle Noise in Laser Doppler Vibrometer on Moving Platforms (LDVom)

Laser Doppler vibrometer (LDV) is a vibration-detecting instrument for noncontact and non-destructive measurement. It is superior to classic contact transducers in terms of the wide frequency range and high measurement resolution. LDV on moving platforms (LDVom) is one of the LDV measurement technology to one-way scan the vibrating surface, so...

Investigation of the chatter and squeal phenomenon in bicycle disc brakes

Bicycle disc brake noise and vibration, which usually falls in the frequency range of 0-2 kHz, is a principal braking quality attribute that has started to attract significant interest from bicycle manufacturers. Brake noise is an irritant to their customers, who see it as a symptom of a defective brake and that leads to unnecessary warranty...

Speckle noise reduction for structural vibration measurement with laser Doppler vibrometer on moving platform

Speckle noise is a major problem for structural vibration measurements with Laser Doppler vibrometer on moving platform (LDVom) due to its highly random, frequent, and broadband nature, especially at high speeds. This paper develops a new post-processing framework to reduce speckle noise based on a case study of LDVom measurements on railway...

Numerical simulation and characterization of speckle noise for laser Doppler vibrometer on moving platforms (LDVom)

Laser Doppler Vibrometer (LDV) is extensively applied in remote and precise vibration measurements for structural monitoring. Speckle noise is a severe signal issue restricting LDV applications, mainly when an LDV scans from moving platforms. Realistic simulations and thorough characterizations of speckle noise can support the despeckle...