Numerical analysis of ultrasonic guided waves propagation in highly attenuative viscoelastic material

The propagation of ultrasonic guided waves in viscoelastic isotropic material has been investigated. Based on the plane theory, a numerical model of the guided waves propagating is developed in the frequency domain by employing the SFEM (spectral finite element method). To verify the proposed method, thin bitumen on the steel substrate is examined and compared with the single plate in terms of the dispersion and attenuation. From the dispersion and attenuation of the displacement curves, the propagating properties can be obtained, which depends not only on the viscous parameter, but also on those of the substrate. The guided wave attenuates rapidly at the location near the source, and with the receiver distance increasing, it becomes slowly, compared with single bitumen, the attenuation of amplitude for the guided waves propagating in the viscoelastic is tend to gently. The phenomenon shows propagation distance will increase in bilayer material cause of the substrate influence.