An Effective Passive Noise and Vibration Control Material

SMACSONIC is evaluated for acoustic characteristics and vibration mitigation. Sound fields transmitted through 2 mm thick aluminum panels with and without SMACSONIC are assessed. The acoustic lab is composed of the big anechoic chamber connected to a semi-anechoic chamber by a rigid wall including an opening where the test sample is installed. The principle of the meas-urement is based on an acoustic field as the input in the emission chamber and measuring the transmission of sound through the test sample. The transfer function is calculated using two-measurement points on both sides of the panel being tested. These measurements are repeated on several reception points to compensate for variation in the microphone position. The measurements are conducted in the frequency band from 50 Hz - 8 kHz, broken into three sub-bands in order to improve signal to noise ratio. The improvement in loss factors are between 2 - 12 dB depending on the frequency. The damping characteristics are measured as an indication of vibration mitigation. Damping loss factor ranges from 18%+- 42%+for damping thicknesses from 1.3 - 2.4 mm, respec-tively, at cold temperature of -30C. The damping loss factor ranged from 28%+- 48%+at 0 oC.