Dispersion curves and identification of elastic wave modes for fiber metal laminates

The current work is devoted to the problem of the validation of dispersion curves and numerical simulations of fundamental Lamb wave and shear horizontal elastic wave modes for fiber metal laminates (FML). In the present study, two types of FM laminates are considered. In the first case, the studied composite material consists of 7 layers: one layer is made of aluminum alloy AW-6060 while the rest of the layers are made of carbon/epoxy resin. In the second case, the FML is constructed of one layer of aluminum alloy and the rest six layers are made of glass/epoxy. In order to extract the dispersion curves for the fundamental SO, SHO, and AO modes, as well as higher modes from the range 5 up to 1000 [kHz], the stiffness matrix method, is employed. In the first case the computations are performed for the following cross-ply stacking sequences: [Al, +/- 5(6)degrees], [Al, +/- 15(6)degrees], [Al, +/- 25(6)degrees], ... , [Al +/- 85(6)degrees]. Next, the FEM simulations of elastic wave propagation are performed in the case of plates, which are made of analyzed FML composites. In the first studied FML material, the fundamental symmetric mode SO is generated while in the second case the fundamental antisymmetric mode AO is excited. It occurred that in the case of aluminum alloy/carbon fibers the generation of the pure fundamental symmetric mode SO is very difficult. In addition, the fundamental symmetric mode SO, the shear horizontal SHO, and the antisymmetric AO wave modes are also present. In the case of aluminum alloy and carbon/epoxy, the pure antisymmetric mode AO can be relatively easily generated. However, a significant dispersion phenomenon is visible. For the aluminum alloy and glass/epoxy, the obtained results are experimentally verified.