Acoustic emission

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

Moment tensor analysis of acoustic emission for cracking mechanisms in concrete

Abstract: A quantitative analysis of acoustic emission (AE) waveforms, which was developed as a Simplified Green's Function for Moment Tensor Analysis (SiGMA) code, is revised. By the analysis, cracks of AE sources are located, classified into a tensile crack and a shear crack, and their orientations are determined. For practical application to concrete, both experimental and analytical procedures are reexamined on the basis of the background theory of moment tensor. To apply the SiGMA analysis to AE waveforms recorded, a basic experimental procedure is discussed and established. In the tensile test of an L-shaped reinforced concrete model, nondestructive evaluation (NDE) of cracking mechanisms is investigated. To improve the accuracy of SiGMA solutions, a postanalysis is developed. Unreliable solutions are screened out, based on the discrepancy between SiGMA solutions of the experiment and those of synthesized waveforms. The mechanisms of the fracture process zone are studied in the bending test of a notched mortar beam. These results demonstrate the applicability of the moment tensor analysis to both NDE of concrete structures and to experimental fracture mechanics in concrete.

Application of acoustic emission to seeded gear fault detection

Abstract: Acoustic emission (AE) is gaining ground as a non-destructive technique for health diagnosis on rotating machinery. There are vast opportunities for development of the AE technique on various forms of rotating machinery, including gearboxes. This paper reviews some recent developments in application of AE to gear defect diagnosis. Furthermore, an experimental investigation that examines the effectiveness of AE for gear defect identification is presented. It is concluded that application of the AE technique to seeded gear defect detection is fraught with difficulties. In addition, the viability of the AE technique for gear defect detection from non-rotating components of a machine is called into question.

Fiber-optic sensor applications in civil and geotechnical engineering

Abstract: Different types of fiber-optic sensors based on glass or polymeric fibers are used to evaluate material behavior or to monitor the integrity and long-term stability of load-bearing structure components. Fiber-optic sensors have been established as a new and innovative measurement technology in very different fields, such as material science, civil engineering, light-weight structures, geotechnical areas as well as chemical and high-voltage substations. Very often, mechanical quantities such as deformation, strain or vibration are requested. However, measurement of chemical quantities in materials and structure components, such as pH value in steel reinforced concrete members also provides information about the integrity of concrete structures. A special fiber-optic chemical sensor for monitoring the alkaline state (pH value) of the cementitious matrix in steel-reinforced concrete structures with the purpose of early detection of corrosion-initiating factors is described. The paper presents the use of several fiber-optic sensor technologies in engineering. One example concerns the use of highly resolving concrete-embeddable fiber Fabry-Perot acoustic emission (AE) sensors for the assessment of the bearing behaviour of large concrete piles in existing foundations or during and after its installation. Another example concerns fiber Bragg grating (FBG) sensors attached to anchor steels (micro piles) to measure the strain distribution in loaded soil anchors. Polymer optical fibers (POF) can be — because of their high elasticity and high ultimate strain — well integrated into textiles to monitor their deformation behaviour. Such “intelligent” textiles are capable of monitoring displacement of soil or slopes, critical mechanical deformation in geotechnical structures (dikes, dams, and embankments) as well as in masonry structures during and after earthquakes.