Numerical simulation-based noise assessment computational strategy for lattice metamaterial sandwich shell structures with double curvature considering elastic boundary effect

This approach is the first investigation to numerically predict sound transmission loss (STL) of a truss-based lattice metamaterial doubly curved sandwich system (TLM-DCSS) considering different cellular cores, including pyramidal (P), tetrahedral (T) and 3D-Kagome (3DK). Although these structures have attracted much attention due to their multifunctional and lightweight features, they are not sufficient even in presenting low-frequency STL, especially when the structure is thick. Herewith, in order to enhance broadband acoustic insulation without strongly increasing mass and modifying structural complexity, an efficient strategy is to model the STL of these systems by considering elastic boundary (EB) effect. Accordingly, in the first part of the study, analytical and numerical approaches are developed to present the vibroacoustic feature of the TLM-DCSS using a diffuse acoustic field (DAF). By integrating the wave over all possible incident angles, a method is expanded wherein not only the structural equations are extracted using a third-order approach (TSDT), but also the acoustic analysis is performed considering the fluid-structure coupling. In addition to using data reported in the literature, finite element (FE) numerical analysis is applied to prove the exactness of the findings. According to the COMSOL results, it is revealed that although the dynamic behavior of the TLM-DCSS can be interpreted based on the FE method, the STL prediction is challenging. Eventually, the EB effect is considered to modify the vibroacoustic response of the thick TLM-DCSS. The results illustrate that modeling the system based on the EB effect improves the acoustic efficiency of the TLM-DCSS by up to 5.8 ( d B ) , particularly for thick structures. Based on the findings, it is also found that unlike the 3DK-type, the P-type lattice shows the highest STL enhancement in the frequency domain between 360 and 6400 ( H z ) , which confirms the positive performance of the designed model for lightweight and high-stiffness Metastructures.