Sound transmission through double-panel partitions with strong and weak coupling analysis

Double-panel partitions are widely used in modern marine and aerospace structures owing to their light weight and high transmission-loss. In this paper, the sound transmission through a finite double-panel partition installed in an infinite baffle is studied. A general fully coupled vibro-acoustic model is developed, taking into account of the interaction among two parallel thin elastic plates, air cavity, and surrounding fluids. Possible model simplification in the cases of strong and weak couplings is discussed. Based on the model, effects of an attached discrete mass in the incident panel and the fluid loading on the receiving panel to the sound radiation and transmission are investigated at low frequencies. Upon model simplification, fundamental frequencies of the coupled system are estimated, which can help locate the discrete mass in the incident panel to avoid deteriorations in sound isolation. Numerical results show that the effect of the attached discrete mass to the sound transmission strongly depends on both its value and location, and the fluid loading significantly influences on the motion of the plate on which it directly acts. Some distinct zones are identified in transmission-loss curve, within which sound transmission is dominated by different physical parameters.