Elastic Mass Actuator (EMA) concept for Sound Transmission Loss increase of panel like structures

摘要

The Elastic Mass Actuator (EMA) is a dynamic mass absorber controlled by active means. Simulations have proved that the harmonic distortion, being very low, is not a relevant parameter with EMA, due to its symmetric construction. With the optimized parameter values 1 urn amplitude can be achieved with a signal voltage of 20V. This is enough e.g. for facade elements in buildings, but applications where higher amplitudes are needed will require rather large alterations in the construction. The properties of EMA have been studied also experimentally by measuring the displacement and phase distributions of the actuator, and by using EMA to actively reduce the vibration of a sandwich plate construction. The reduction ratios of EMA (ratio of displacements control on to control off) have varied from 0.54 to 0.65 (mean 0.6) at single frequency excitations and around 0.65 at narrow band excitations. The first EMA element is not able to reduce sound pressure levels due to its non-even phase and displacement distributions.