MEASUREMENT OF STRUCTURE-BORNE SOUND EMISSION FROM RESILIENTLY MOUNTED MACHINES IN SITU

摘要

The aim of the work presented in this paper is to test, in the held, a method for the prediction of structure-borne sound emission from resiliently mounted machines. The vibrational power injected into the machine seating is the structure-borne equivalent of the (airborne) sound power. Initially, an error analysis is carried out to show the sensitivity of the measurement method to various sources of error. The vibrational power, which is assumed to have a vertical component only, through the mounts of two compressor installations is then measured in situ. The prediction requires knowledge of the dynamic properties of the resilient mounts and the machine seating (floor), together with the free velocity of the machine. These quantities are measured in situ for the two compressors. Good agreement between the measured and predicted power is obtained in the first case, particularly at frequencies below 250 Hz. in the second case, discrepancies are attributed to transmission paths not accounted for in the prediction such as flanking transmission via pipes. This raises the possibility of the measurement and prediction method being used together to demonstrate the presence of a significant flanking path. power from rotational motion is shown not to contribute significantly in the frequency range up to 200 Hz. [References: 11]