Geometric nonlinear dynamic analysis of MLC cylindrical shells with FGM core under impact load using by finite element method

In recent decades, shells made of composite materials have been used in modern structures under impact load. Multi-Layer Composites (MLC) and Functionally Graded Materials (FGMs) are the upgrades of composites that have been considered due to their suitable mechanical properties such as high resistance to weight ratio, flexibility and impact resistance. In this research, geometric nonlinear dynamic behavior on multilayer composite cylindrical shells with FGM core under impact load has been analyzed; Because it is necessary to know how structures made of these materials behave under such loads. For this purpose, the effect of FGM core volume fraction index and the effective parameters of multi-layer composites such as the angles of the layers and the number of layers have been investigated. The results of this study show that by increasing the volume fraction index, the maximum displacement of the shell decreases. The maximum displacement occurs in the CFC (CFRP/FGM/CFRP) shell with pure metal FGM and the minimum displacement occurs in the GFG shell with pure ceramic FGM. Evaluation of the different positions of the layers shows that selecting a 15-degree positioning angle causes less displacement and also decreases the displacement as the number of layers increases.