Computational simulations of wave propagation in microcrack-damaged media under prestress

Direct computational simulations of unidirectional wave propagation through uniaxially prestressed, microcrack-damaged media are conducted to study the interaction between the prestress and stress wave parameters. Tensile and compressive waves, tensile and compressive prestresses and various orientational distributions of microcrack damage are analyzed. The relationships among the input wave amplitude, wavelength and prestress magnitude and the output wave speed and wave attenuation are studied. The results show that wave speed and attenuation depend on the prestress and the wavelength in a complex way. In the cases of compressive waves traveling through tensile prestress and tensile waves passing through compressive prestress, the wave response depends on the ratio of the amplitude of the applied stress pulse to the magnitude of the prestress (defined as R). Specifically, the simulations show that the compressive wave speed through tensile prestressed media increases gradually with an increase in R, while the tensile wave speed in media under compressive prestress, decreases with increase in R, but the change is abrupt at a particular R value. In the cases of sufficiently small R, the wave speeds match the results of Su et al. (Eng Fract Mech 74:1436–1455, 2007) where the cracks are always open or always closed. However, above a certain wavelength (a cut-off wavelength), the wave speed is no longer a function of wavelength and, furthermore, this cut-off wavelength varies with R.