The correlation of acoustic emission with rate of corrosion

Acoustic emission monitoring of slow strain rate tensile tests of 304L stainless steel in supercritical water environment

Studies have been conducted that suggest that it is feasible to use acoustic-emission and radar techniques for the nondestructive testing of masonry and of bridge cables. The examination of the condition of a brick railroad tunnel was carried out by using both techniques. Radar was used to determine the conditions of several reinforced concrete roadways and bridge decks. Acoustic emission was used in a novel way involving the application of small stresses to bridge cables, and the resultant emission pattern was correlated with the condition of the cables. The equipment used is discussed in some detail, as are the uses of special techniques for obtaining and analyzing the data. Several means of loading the bridge cables to obtain the acoustic emission were used; the use of an air hammer is the most effective technique found thus far. Several photographic techniques were developed to correlate the mass of data obtained from radar studies of roadways. These photographic techniques and the advantages of each are discussed in some detail. It is concluded that radar and acoustic emission are potentially useful tools for nondestructive testing of masonry and bridge cables. /Author/

Radar and acoustic emission applied to study of bridge decks, suspension cables, and masonry tunnel

In April 1967, 42 engineers and scientists concerned with the troublesome and costly problems of mechanical failures met at the Office of Naval Research to form the Mechanical Failures Prevention Group (MFPG). The participants, who represented several government agencies and industries, met to develop a forum to exchange information and innovative ideas on methods to avoid or predict mechanical failures in a wide variety of vehicles, equipment and structures. This meeting was the genesis of a broad interdisciplinary society that has become and serves today as a powerful resource in the field of machinery failure prevention, analysis, diagnostics and prognostics. This article, an updated revision of a paper published in the proceedings of MFPT 50, describes the developments and progress in mechanical failure prevention technology, primarily over the last four decades. The principal sources for this overview are the proceedings of the 49 conferences of the MFPG, which has become the Society for Machinery Failure Prevention Technology (MFPT) and is an operating division of the Vibration Institute.

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An Historical View of Mechanical Failure Prevention Technology

Application of acoustic emission analysis to hydrogen-assisted cracking

The combination of acoustic emission and linear fracture mechanics can provide quantitative information regarding failure. This report has shown that, for certain situations, acoustic emission techniques can be used to accurately estimate the stress intensity factor K at a growing crack, and therefore provide predictive information regarding structural failure. The importance of locating defects in large complicated structures, such as bridges and power plant pressure vessels, was also stressed, and a multiple-channel computer system was described for accomplishing this function. The ability to locate a growing defect, coupled with the ability to quantify the growth rates with fixed sensors (no scanning required) places acoustic emission in the forefront of new techniques for the prevention of structural failures.

H L Dunegan

Papers

Using acoustic emission technology to predict structural failure