Papers by Author: P.T. Cole

Abstract: Conventional methods of acquiring and using acoustic emission (AE) discard the raw signal waveform after extracting signal features from it. The main reason for this is the number of bytes required to save hundreds of thousands of AE waveforms, using a modern high speed multichannel system the hard-drive may be quickly filled. One side effect of this “feature extraction” approach is that information is thrown away with the wave-form. The advent of systems capable of acquiring AE waveforms on all channels has opened up the opportunity to use this extra data to get more information about the source and the transmission path. This paper describes the use of acoustic emission waveforms to aid source discrimination, and presents data acquired during pressure testing of a slug-catcher.

Abstract: Corrosion is the major cause of structural degradation in industrial plant and structures; the consequences of not identifying its presence and status can be severe, leading to a myriad of methods for its evaluation and monitoring. Amongst these there are a large number based on acoustic methods, and this paper concentrates on three variations involving passive monitoring with the aim of summarizing their usual area of applications and limitations. Passive monitoring involves listening to the process of corrosion itself, which usually causes acoustic emission as a result of the fracture and de-bonding of expansive corrosion products, localised yielding, or micro-crack formation. This method is applied to reinforced concrete structures, storage tank floors, and process plant whilst in service.

Abstract: A novel fibre optic sensor system has been developed for detection of acoustic emission. The sensor design was based on a 2×2 fused tapered optical fibre coupler configuration. Given the intended use of this sensor for the detection of acoustic emission in smart materials and structures, its lightweight, compatibility with composite material and immunity from electromagnetic interference are great advantages. Apart from the performance specification and reliability, the overall cost of the sensor system is a major factor in their adoption by end-users. The manufacturing of this sensor is low-cost and the signal output from the sensor system developed can be directly fed to the commercial AE acquisition system. The demonstration of acoustic emission detection was conducted using fibre coupler-based AE sensors in different materials and structures. The AE sources are various and depend on the different applications. In the current paper, we report on the use of the fibre optic AE sensor system for concrete damage monitoring. An experiment on damage detection on a composite plate with this fibre optical AE sensor is also reported in the paper.