Numerical study of nonlinear interaction between a crack and elastic waves under an oblique incidence

• Finite Element Modeling of wave nonlinear interaction with a crack.
• The crack is modeled by an interface of unilateral contact with Coulomb’s friction.
• Explanation of the generation of higher harmonics by the study of contact stresses.
• Study of the coupling between normal and tangential behavior.

A Finite Element (FE) model is proposed to study the interaction between in-plane elastic waves and a crack of different orientations. The crack is modeled by an interface of unilateral contact with Coulombs friction. These contact laws are modified to take into account a pre-stress σ0σ0 that closes the crack. Using the FE model, it is possible to obtain the contact stresses during wave propagation. These contact stresses provide a better understanding of the coupling between the normal and tangential behavior under oblique incidence, and explain the generation of higher harmonics. This new approach is used to analyze the evolution of the higher harmonics obtained as a function of the angle of incidence, and also as a function of the excitation level. The pre-stress condition is a governing parameter that directly changes the nonlinear phenomenon at work at the interface and therefore the harmonic generation. The diffracted fields obtained by the nonlinear and linear models are also compared.