Quasistatic pulse generation of ultrasonic guided waves propagation in composites

In this paper, the generation of quasistatic pulses (QSPs) of guided waves propagation in fiber reinforced plastic (FRP) thin plates is investigated. Numerical perspective of the generation, propagation, and mode conversion of QSPs of GWs in the composites are obtained. It is indicated that the displacement direction and generation efficiency of QSPs depend on the wave propagation direction, the coefficients of the strain energy function, and the primary GW field. Group velocity, wave structure, and wavenumber domain analyses show that the generated QSPs are either S0 mode, or partly coupled S0 and SH0 modes with only in-plane displacements with different direction, regardless of the excitation of primary waves. For GWs propagation in principal material directions, comparative studies show that the generation efficiency of QSPs are depended on both the mode types and primary GW propagation direction. With the considerations of both cumulative effect and the divergence effect, comparative study of generation efficiency of QSP and second harmonics shows that, although the divergence loss is not negligible, appropriate excitation of primary GW can achieve a higher efficiency of cumulative QSP generation than that of the phase matched second harmonics.