Contribution of System Noise to Vibration Information

Vibration and noise are two inter-related physical phenomena as well as two reciprocity quantities, i.e., vibration always induces noise, or noise is due to the energy radiation of vibration. Although they are closely related, there is no practical conversion equation between them. It would be highly practical and prospective to dig out system vibration information from system noise data, because system noise signals are easy to be acquired by non-contact measurements, while vibrations usually are acquired by contact measurements, which are limited by a variety of objective conditions, and sometimes even impossible. Based on the noise-vibration theory, the relationship between one-third-octave frequency bands and the Z levels of vibration acceleration spectrum is developed by means of the statistical energy analysis in this paper. The vibration levels of the body side panel of carriages were estimated from the noise data which were measured when high-speed train passing tunnels. As a result, it is shown that the vibration levels predicted by the noise data are in good agreement with the field vibration measurements.