A finite element study of transient wave propagation in plates

Studies of transient wave propagation in plates were carried out to establish a basis for the impact-echo technique as a nondestructive test for flaw detection in concrete. The surface displacements caused by stress waves generated by point impact on a plate were calculated using both the Green’s function solution and the finite element method; displacement waveforms obtained by the two approaches showed good agreement. Displacement and stress fields in a plate were studied using finite element analysis. It was shown that transient point load applied normal to a stress-free boundary gives rise to P- and S- “wakes”—disturbances trailing the P- and S-waves. The displacement and stress fields in each wake resemble those in the preceding wave.