Crack mode analysis of cement mortars with signal - based acoustic emission techniques

Abstract

Determining the crack mode in structures made of brittle materials, such as concrete and masonry, is important for structural analysis and failure prediction. Fractures monitored with the acoustic emission technique (AE) are commonly classified into different modes using Rise angle (RA) – Average Frequency (AF) analysis, the simplified Green's functions for moment tensor analysis (SiGMA), and frequency spectrum analysis. However, the classification limits are dependent on the material, the test setup, and the monitoring condition. Hence, this study defines these limits by comparing the three AE-based fracture mode analysis methods on AE data collected from three test types on mortar specimens. In a direct tensile test, the peak frequencies of most of the AE events were higher ( >60 kHz). While almost all of the AE events in a friction test had significantly lower peak frequency (

Fatigue fracture quantification in brittle cementitious materials using acoustic emission testing and digital image correlation

“…The crack mode of the located AE events is investigated using the rise angle (RA), and the average frequency (AF) of the first AE hit in the event. The basis of classification is based on the findings of the author's prior work [49]. The mode of AE events was identified as a tensile mode when the ratio between the AF and RA is above 0.5.…”

Micromechanics-based variational phase-field modeling of Brazilian splitting tests

“…However, the difficulties in determining the point of crack initiation in experimental setups have led to debate over the validity of the measured tensile strength [10]. Recent research has examined fracture patterns in the Brazilian splitting test, both experimentally and numerically [11,12], and found that the crack initiation point can vary [13]. Some studies have reported that the crack initiates and propagates from the area under the loading points [14], while others have found that it starts at the center of the disc [15].…”