Under the incidence of plane acoustic wave, the sound transmission loss (STL) of a finite double-panel structure with enhanced columns is investigated in different surrounding fluids. The columns arranged evenly in intermediate cavity are replaced by translational and rotational springs. By using space harmonic expansions and orthogonal modal theory, the STL of whole structure is calculated theoretically and the convergence of numerical results is analyzed. Compared with other known methods, the calculated results are reliable and present theory is validated. The effects of different surrounding fluids, enhanced columns and incident wave are discussed. Finally, some conclusions are obtained which may play important roles in practical engineering.
Double-panel structure is a classic research object in sound insulation field, and Fahy et al. (2007) and Du et al. (2012) have done a lot of fundamental researches on it. After them, many scholars enrich the study domain of double panels.
The sound insulation research of double plates mainly focuses on the infinite and finite double-plate structures with internally reinforced cores. Based on a simply smeared model and a periodic model, sound transmission problem of infinite double-leaf structure stiffened with periodically placed studs is researched by Lu and Wang (2005), and the advantages and disadvantages of both models are analyzed. The infinite double panels with pyramidal truss cores and rib-stiffened studs are studied and their sound transmission loss (STL) are calculated by Wang et al. (2017) and Fu et al. (2017), respectively. The Fu et al. (2017) use the first order shear deformation theory to build the theoretical model of double-panel structure, while Wang et al. (2017) take the space harmonic expansions and the principle of virtual work to study the composite sandwich model with pyramidal truss cores.
There also are many researches of sound insulation mechanism about the finite double-plate structure. The numerical and experimental investigations of sound transmission about double panels with structural links are done by Legault and Atalla (2009). The Legault and Atalla (2009) have established some models to analyze the influence of periodically structural links on double-panel structure and describe the advantages of decoupled approaches to predict the STL of that double-panel model. After that, considering the clamped double-panel model, its theoretically calculating formulation about sound insulation is derived completely by Xin and Lu et al. (2008, 2009), and its result of STL is validated by experimental data. The Galerkin method is used to solve the sound insulation problem of clamped double-panel structure with poroelatic materials by Liu et al. (2017). Sound insulation problem of simply supported sandwich structure with corrugated core is analyzed by using homogeneous layer theory (Chen et al, 2012). The model predictions of Chen et al. (2012) are validated through the comparison with existing experimental measurements and the physical mechanisms of sound transmission through double-panel structure also are explored.
