Acoustic emission

About: Acoustic emission is a research topic. Over the lifetime, 16293 publications have been published within this topic receiving 211456 citations.

Detection of severe sliding and pitting fatigue wear regimes through the use of broadband acoustic emission

Abstract: Acoustic emission techniques have been used to monitor severe sliding and pitting fatigue processes during four-ball testing. Results are presented that arose from a collaborative programme between the Naval Research Laboratory (Washington, DC) and the University of Wales Swansea, sponsored by the US Office of Naval Research. The ultimate aim of the research is to develop a systematic fusion technology approach to condition-based maintenance of wear-related surface distress of critical components in naval air and surface combatant engine and transmission systems. The principal monitoring technique utilized in this investigation was acoustic emission (AE). A custom data acquisition system was developed using a novel approach to collect AE signals. Post-test analysis of the data, in the frequency domain, demonstrates the advantage of analysing continuous AE and not just AE pulses.

Investigation of low temperature cracking in asphalt mixtures by acoustic emission

Abstract: This paper investigates the use of acoustic emission (AE) to characterize microstructural phenomena and the corresponding macroscopic behavior during the low temperature fracture of asphalt mixtures. An acoustic emission system with eight channels of recording was used to monitor the failure process during testing at low temperature using the semi circular bend (SCB) configuration in three Superpave mixtures used at MnROAD facility. Algorithms to automatically detect the relative arrival time of the AE signal and to locate the AE source were developed. The analysis of the accumulated AE events illustrated the relationship between the micro damage and macroscopic behavior at different loading levels. The damage level under certain loading conditions was evaluated and preliminary results showed that the load level corresponding to the localization played a critical role in the damage process of the material. As a first step, the fracture energy of asphalt concrete specimen was related to the accumu...

The b‐Value Analysis for the Stability Investigation of the Ancient Athena Temple in Syracuse

Abstract: Some of the most significant architectural works are monumental masonry constructions. Among these, the Cathedral of Syracuse can be viewed as a fundamental element in the cultural heritage of Europe. For the preservation of these monuments, it is necessary to assess their durability by taking into account cumulative damage and cracking conditions in the structures. The paper describes the methods used by the authors to determine the conditions of the materials and the crack patterns in the stonework structures of the Cathedral. In particular, the acoustic emission (AE) technique is used to evaluate the time dependence of damage and the onset of critical conditions in a pillar, which is part of the vertical load-bearing structures. The authors show that the damage evolution in the stonework structures, experimentally investigated in situ by the AE technique, can be described by a power law characterised by a non-integer exponent, βt. In this way, the time dependence of damage is evaluated by working out the βt exponent and making a prediction of the stability conditions of the structure. Furthermore, the achievement of the critical condition is characterised through another synthetic parameter, the b-value of the Gutenberg-Richter law. The b-value systematically changes during the different stages of the failure process and tends to 1.0 as the structure reaches the final collapse. In the present study, this behaviour is documented by several AE tests carried out on specimens of different dimensions extracted from the pillar. In addition, these results are compared with the AE data obtained from the in situ-monitored pillar.

A Microseismic/Acoustic Emission Source Location Method Using Arrival Times of PS Waves for Unknown Velocity System

Abstract: To eliminate the location error of MS/AE (microseismic/acoustic emission) monitoring systems caused by the measurement deviations of the wave velocity, a MS/AE source location method using P-wave and S-wave arrivals for unknown velocity system (PSAFUVS) was developed. Arrival times of P-wave and S-wave were used to calculate and fit the MS/AE source location. The proposed method was validated by numerical experimentations. Results show that the proposed method without the need for a premeasured wave velocity has a reasonable and reliable precision. Effects of arrival errors on location accuracy were investigated, and it shows location errors enlarged rapidity with the increase of arrival errors. It is demonstrated the proposed method can not only locate the MS/AE source for unknown velocity system but also determine the real time PS waves velocities for each event in rockmass.

Investigation of acoustic emission signals under a simulative environment of grinding burn

Abstract: Grinding burn is a common phenomenon of thermal damage that has been one of the main constraints in grinding in respect of high efficiency and quality. An acoustic emission (AE) technique was tried in an attempt to identify grinding burn on-line. However, the AE features of grinding burn are relatively weak and are easily obscured by other AE sources. This paper presents an investigation of the AE features of the thermal expansion induced by laser irradiation, which was designed to simulate grinding thermal behaviour. By using wavelet packet transforms, AE features at the grinding burn temperature can successfully be extracted without other mechanical interferential factors. Such thermal AE features provide a firm foundation for analysing and monitoring the AE features of grinding burn.