Investigation of Lamb Waves Propagation in Variable Stiffness Fiber Metal Laminated Plates Using Finite Element Method

Lamb waves are mechanically guided waves that propagate through plates and shells, and their speed depends on the frequency. Nowadays, researchers use these waves to detect defects in structures. This is due to the properties of Lamb waves that can propagate in the whole structure, and are quickly affected if there is a defect. Using this method instead of traditional methods due to their complexity, cost and time are desired. As an innovation in this research, the effects of lamb wave propagations in symmetrically variable stiffness fiber-metal laminated plates are investigated and for this purpose, the finite element method is used. In this analysis, curvilinear fibers are used in the composite layers instead of the straight fibers, and the effect of the number of layers, plate dimensions, and boundary conditions on the propagation of the mentioned waves are investigated. Also, to check the validity, the first three frequencies of the structure are compared with several different references. The obtained results show that the Lamb waves are propagated along the length of the plate and are reflected by hitting the boundaries of the plate or defect in the structure and lose their uniform propagation state. Based on this investigation, this method can be used to detect the defect in variable stiffness fiber-metal laminated structures.