The nonlinear Lamb waves generated in the layered plates due to the presence of micro-cracks are studied. And the single-mode Lamb wave is obtained by wedge incidence method, and the interactions between the Lamb wave of a specific mode and micro-cracks of various lengths and various positions are simulated using the finite element method. The numerical results show that the Lamb wave can generate the second harmonic after interaction with the micro-cracks, and this nonlinear effect is closely related to the length of the cracks, which can be used for the detection of early micro-cracks in different directions. However, the degree of nonlinear effect waves is different when micro-crack extend from one medium to other in layered plate or detecting in different surface of layered plates, this is mainly due to the changes of material properties. Besides, the amplitude of second harmonics is influenced by crack and the location of receivers.

layered plates; nonlinear Lamb waves; finite element method