Last modified: 2021-06-01
Abstract
The formation, growth and propagation of cracks in solid media are associated with energy release in the form of – among others – elastic waves. Those disturbances propagate from the crack to surfaces of the medium as acoustic emission (AE) signals. The detection, acquisition and analysis of AE signals can supply information regarding the origin and characteristics of the crack, and form one of the major aspects of non-destructive testing and structural health monitoring. Understanding of crack dynamics and characteristic signal features correlated with the type and location of a crack is therefore of high importance for integrity and evaluation of structural health. This paper reports on the impact of AE source modeling methods and the propagation path models on the acquired acoustic emission signals.
Analytical AE source modeling has been widely explored over the last decades. Discontinuities, as cracks, are typically modeled as a combination of force-dipoles. These models use the Green’s function approach to propagate AE signals from the source till the surface of the medium. The above analytically-described sources in numerical simulations are subsequently filtered through the numerical dispersion properties that are functions of the spatial discretization and time step. In this paper, we explore the influence of various numerical phenomena on the modeled AE sources and signals, and compare them with analytical results. Two types of AE sources are modeled, namely, analytical sources representing the crack as a combination of force-dipoles and finite element-based crack sources that are modeled using cohesive zones.