Four vectors of Lamb waves in composites: Semianalysis and numerical simulation

For source location in composites based on Lamb wave techniques using direction-dependent piezoelectric rosettes sensors, the source is usually located by the intersection of wave propagation directions identified by the sensors. However, the rosettes do not measure the direction of group velocity directly. Instead, they measure the direction of principal strain. Hence, in order to accurately predict the sources in anisotropic plates, it is essential to investigate the relationship between the direction of principal strain and that of group velocity. In this study, the four vectors, namely, phase velocity, group velocity, displacement, and principal strain associated with propagating waves in anisotropic plates, are computed using semianalytical methods. The analytical results agree very well with the results of finite element method based on Abaqus, including those of the complicated SH ₀ mode. Moreover, it is found that the four vectors exhibit some symmetrical properties. When Lamb waves propagate along the symmetry axes, the directions of the four vectors are all the same.