Effects of isolating machine vibrations on the transmission of structure-borne and air-borne sound energy

摘要

A large proportion of noise is generated by the vibration of machines and rigid structures such as industrial equipment and machines in buildings. Well-designed vibration isolation of potential vibrating sources can effectively reduce the transmission of energy into supporting and surrounding structures. The presented paper investigates the conditions for reducing the transmission of structure-borne sound from their vibration sources, such as combustion engines and other rotating machines, by introducing vibro-isolating components at the support of the machines or other industrial equipment. The solution of this problem is based on the theoretical knowledge and methodology of the transmission of longitudinal and transverse waves and measurement of the structures involved. Measurement of vibration at the sources and after the vibro-isolating elements, as well as sound measurements at a given point, were performed. The results of the vibration measurements were compared for different conditions and configurations of vibro-isolating elements. Application of specific vibro-sound sources with respect to blocking forces and wave transmission where also performed to determine their effects on the machine foundation and transmission of energy to its surroundings. Measurements were performed for different machine mounting and vibro-isolators to compare real results with that of theory. Vibration and sound were measured and an FFT analysis was used to detect transmission loss. In the first case, mainly low-frequency vibration is analysed at the machines mounting and the transmission of structurally-borne waves through isolators were investigated. Finally, the paper suggests some measures which can reduce unwanted vibro-sound energy acting on machine foundations, buildings and industrial structures.