Time Reverse Characterization of Sources in Heterogeneous Media

Time reverse modeling (TRM) is applied to localize and characterize acoustic emission using a numerical concrete model. The aim is to transform a method within exploration geophysics to non-destructive testing. In contrast to previous time reverse applications, no single event or first onset time identification is applied. The method is described from a mathematical point of view. So-called source TRM with limited knowledge of boundary values is used in combination with several imaging conditions. TRM localization and characterization using this highly scattering material is feasible using the rotated staggered finite-difference method. We demonstrate the localization of two synchronous acoustic emissions with a limited number of sensors and using effective elastic properties. Source characteristics can also be recovered. The goal is to apply our method to acoustic emissions measured during experiments carried out on concrete and reinforced concrete specimen. Several aspects of the described methodology can also be transferred back to exploration geophysics.