Numerical computation of ultrasonic wave propagation in concrete using the elastodynamic finite integration technique (EFIT)

Concrete is a strongly heterogeneous solid including aggregates, cracks and porosity. It represents an important but also very challenging object for ultrasonic non-destructive testing methods. The elastic wave propagation in this material consists of a complex mixture of multiple mode conversion and multiple scattering which results in a "diffusive" energy transport. In order to investigate the effect of aggregates, porosity and reinforcement on the applicability and reliability of different testing methods it is useful to model the ultrasonic wave propagation and scattering process explicitly in the time-domain. The elastodynamic finite integration technique represents a stable and efficient numerical scheme to model ultrasonic wave propagation in elastic solids. In the present paper the two- and three-dimensional EFIT code is used to calculate ultrasonic wave propagation and scattering in various concrete specimens modeling pulse-echo, impact-echo and acoustic emission testing methods. The numerical simulations are presented by means of time-domain signals and time-domain wavefield snapshots.