Vibration response of sandwich plate reinforced by GPLs/GOAM

Due to the improvement in the quality of life for people and the increase in the safety of structures, various industries, especially the transportation and construction industry, need to structures with lower lightweight and higher strength. Increasing the strength of structures with decreasing their weight is the motivation for studying composite sandwich structures reinforced with various types of reinforcements and different porous cores. Researchers' motivation is to try to improve the quality of these structures by integrating multiple materials in sandwich composite structures. This motivation has led to the vibration analysis of a rectangular sandwich plate with a porous core and composite face sheet reinforced by graphene platelets (GPLs) and graphene acoustic origami metamaterial (GOAM). This research hypothesizes that the structure is one fabric, and each layer is completely connected to the next and previous layers. On the other hands, it hypothesizes that the delamination phenomenon for each layer does not occur. Also, the reinforcements are completely uniformly distributed in the face sheet layer. Also, the effects of the shear deformation are considered based on the refined third-order shear deformation theory (RTSDT). There are only four unknown functions compared to other theories, while other shear deformation theories require five functions. In this study, three types of porosity distribution are hypothesized and investigated. It shows that the effect of the second type of porosity distribution on the natural frequency is more significant than the other two types. Also, the effect of a higher (n > 2) power index on the aspect ratio is negligible, while it is noticeable for a lower power index. Moreover, it is seen that by enhancing the weight fraction of GPL/GOAM, frequency increases because of increasing the stiffness of structures.