ICSV26

SMACSONIC material is evaluated for both acoustic characteristics and vibration mitigation. For Acoustic evaluation, sound fields transmitted through 2 mm thick aluminum panels with and without SMACSONIC were evaluated. The acoustic lab is composed of the big anechoic chamber connected to a semi-anechoic chamber by a rigid wall including an opening (window) where the test sample can be installed. The principle of the measurement is based on an acoustic field as the input in the emission chamber and measuring the transmission of sound through the test sample. Next, the transfer function was 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 focus of the measurement was in the frequency band from 50 Hz to 8 kHz, broken into three sub-bands in order to improve signal to noise ratio. The improvement in loss factors were between 2 to 12 dB depending on the frequency. As for vibration, the damping characteristics were measured as an indication of vibration mitigation. The Oberst Beam test technique, outlined in ASTM E756, was employed to conduct measurements. The SMACSONIC is applied to an aluminum base beam 340 x 20 x 2mm or 340 x 30 x 2mm in size. Bonding was completed at least 24h before testing. The shaker is placed into the climatic chamber with temperature range from -35°C to typically 35°C with increments of 5°C. Measurement are conducted after a 30 minutes dwell time in order to ensure full thermal equilibrium. The measurements are very robust/repetitive. It is shown that damping loss factor ranged from 18% to 42% for damping thicknesses from 1.3 to 2.4 mm, respectively, at cold temperature of -30C. In addition, it is shown that damping loss factor ranged from 28% to 48% at 0C.