The nonlinear interaction of shear waves with a crack of different orientations is presented. A Finite Element model is proposed to obtain the evolution of the generated nonlinearity when the orientation of the crack changes. The crack is modeled by an interface of unilateral contact with Coulomb's friction. These contact laws are modified in order to take into account a pre-stress σ0 that closes the crack. Finally, the evolution of the higher harmonics is obtained and is related to the nonlinear contact behavior of the crack.