The acoustic emission (ae) technique was used to locate fatigue crack initiation sites and to characterize signals related to fatigue cracks in bridge structural components. An experimental study thatincluded a series of tests on welded and rolled beams was performed. Time and frequency domain analyses were performed on ae signals obtained during various life stages of each specimen. The effect on the ae signals of welding, which changed the material's microstructure, was studied. Two stress ranges and their effect on the ae signals were investigated. An in-service bridge was tested to study its general ae response. Ae signals from growing fatigue cracks had distinctcharacteristcs in both the time and frequency domains. Growing fatigue cracks were detected at relatively early stages of the fatigue lives and the corresponding ae signals were characterized throughout the experiments. This paper appears in transportation research record no. 1268, Higway maintenance operations and research 1990.
Abstract