On the influence of stress gradients on the propagation behaviour of Rayleigh waves

This short communication presents a new combined numerical and signal processing based analysis of the influence of stress gradients on Rayleigh wave propagation. The method uses finite element simulations based on the hyperelastic Murnaghan model, to caputure the acoustoelastic effect, and an adapted coda Wave Interferometry (CWI) technique to quantify time shift and stretch of Rayleigh wave signals. It is shown that the stress gradient alters both wave velocity and wave shape. While tensile stress reduces wave velocity, a stress gradient can counteract this effect and even enhance the propagation velocity. The combined evaluation of time shift and stretch allows an effective description of the influence of both surface stress and stress gradient on the wave propagation.