Acoustic emission

Abstract

Acoustic emission (AE) analysis is about the detection and interpretation of ultrasonic waves caused by rapid internal displacements. In the context used herein, the formation and propagation of cracks in fiber reinforced materials are understood as the most relevant acoustic emission source. This acoustic emission source is generally described as spatial crack surface oscillation [1, 2]. During propagation of the emitted acoustic wave, the characteristics of the signal (e.g., frequency content) suffer from attenuation, dispersion, and propagation in guiding media. In addition, the characteristics of the signals detected at the surface of the solid are further altered by the detection process using piezoelectric sensors. This chapter starts with a short introduction to the principle of operation followed by a sequential review on the acoustic emission source, aspects of wave propagation in guided media, and the signal detection process. Subsequently, signal classification techniques and source localization algorithms are discussed with a particular focus on recent developments. The chapter closes with some applications of acousic emission as in situ technique to monitor failure of fiber reinforced composites.