Anwendungen der Schallemissionsanalyse an Betonbauwerken

Acoustic emission monitoring applications for concrete structures

When structures are loaded they experience internal and external damage which causes the release of elastic waves. These waves radiate outward from the damage source (cracking, micro-fracture) similar to earthquakes. With sensors mounted to the surface, acoustic emission (AE) monitoring captures and analyses these signals. Compared to other techniques such as ultrasonic testing or RADAR which are typically applied after damage has occurred, in AE monitoring the damage source itself generates and thus is represented in the signal which is an advantage. Typically, the ultrasonic frequency range of AE signals - often referred to as micro-seismic events - is analyzed. In contrast to ultrasonic techniques where the recorded signals are usually associated with the geometry of a defect, which is why a member is typically scanned over an area, AE are also related to the irreversible (inelastic) deformations of a member under an applied load. Location and character of the source signals are therefore initially unknown. A reliable interpretation of AE signals is often only possible when the sources (hypocenters) can be located. Applications include crack detection and monitoring of crack propagation or crack surface friction. AE events are often related to a prior mechanical or thermal stress accumulation. AE techniques are therefore particularly well suited for in-service monitoring of structural or mechanical members. In this paper, after an introduction to the basics of the method, examples for applications in member design, material science and applications on reinforced concrete structures are presented and discussed.