The influence of component defect states on bandgaps of 2D composite beam frame structures

This paper investigates the vibration bandgap properties of two-dimensional (2D) periodic composite beam frame structures with component defects. Combined with the topological characteristics of the structure, a generalized position coordinate system is proposed, and an assembly method of the stiffness matrix for the virtual full component model is presented. Then the spectral equations of motion of the whole 2D periodic composite beam frame structures and the ones with component defects are established. Compared with the frequency-domain solutions calculated using the finite element method, the accuracy and the feasibility of the spectral element method (SEM) solutions are verified. It can be shown that the SEM is suitable for analyzing the vibration bandgap properties, and the influence of different component defects and their combination on the bandgap characteristics of 2D periodic frame structures is studied. The results show that forbidden gap splitting will occur in the main bandgap of the structure, but the degree of influence varies. The results also show that the influence of component defects on unsymmetrical or irregular positions of the vibration bandgaps of periodic frame structures is greater than the one in symmetrical or regular positions.