Acoustic Emission Monitoring Method Research Articles

Sheath-outside AE monitoring method for multiple sources of damage to cables considering the effect of an HDPE sheath on AE propagation

Cable is one of the important components of cable-stayed bridges, there are three common damages: broken wire, corrosion and fatigue. High-density polyethylene (HDPE) sheaths will induce the attenuation of acoustic emission (AE) signals of damage to cables. Therefore, three cables with different wire counts are used for AE monitoring. The relationship between the thickness and the AE transmittance coefficient of HDPE sheaths, and a circumferential AE attenuation model are established for each cable. According to the transmittance coefficient and circumferential attenuation model, a sensor arrangement method for monitoring the wire breakage, corrosion, and fatigue of cables is quantitatively given. The results show that the transmission coefficient linearly decreases with an increase in HDPE sheath thickness with a slope of approximately 0.012. The circumferential AE amplitude attenuation rates for the three types of cables are 9.9%, 18.74%, and 21.13%, respectively. Monitoring the wire breakage requires only one sensor; monitoring corrosion and fatigue damage only requires one sensor for the 61-strand cable, symmetrical-arrangement two sensors for cables with 349 and 547 strands.

Revealing the interaction mechanism of pulsed laser processing with the application of acoustic emission

The mechanisms of interaction between pulsed laser and materials are complex and indistinct, severely influencing the stability and quality of laser processing. This paper proposes an intelligent method based on the acoustic emission (AE) technique to monitor laser processing and explore the interaction mechanisms. The validation experiment is designed to perform nanosecond laser dotting on float glass. Processing parameters are set differently to generate various outcomes: ablated pits and irregular-shaped cracks. In the signal processing stage, we divide the AE signals into two bands, main and tail bands, according to the laser processing duration, to study the laser ablation and crack behavior, respectively. Characteristic parameters extracted by a method that combines framework and frame energy calculation of AE signals can effectively reveal the mechanisms of pulsed laser processing. The main band features evaluate the degree of laser ablation from the time and intensity scales, and the tail band characteristics demonstrate that the cracks occur after laser dotting. In addition, from the analysis of the parameters of the tail band very large cracks can be efficiently distinguished. The intelligent AE monitoring method was successfully applied in exploring the interaction mechanism of nanosecond laser dotting float glass and can be used in other pulsed laser processing fields.Graphical

Uniaxial tension damage mechanics of steel fiber reinforced concrete using acoustic emission and machine learning crack mode classification

This paper presents a new scalar plastic damage constitutive model in tension for steel fiber reinforced concrete. It considers the coupled mechanism of matrix bridging and fiber bridging using the Helmholtz free energy. A total of 27 steel fiber reinforced concrete specimens with three concrete matrix strengths and three fiber volume fractions were subjected to three-point bending tests. The acoustic emission monitoring method was utilized to detect the evolution of the released strain energy within the fracture process zone. A machine learning based framework was designed to classify the acoustic emission signals into tension-crack mode and shear-crack mode ones. The relationships between the fiber volume fraction and the plastic strain and between the characteristic length and crack opening displacement were identified. Furthermore, empirical expressions for the two damage variables dm and df corresponding to concrete matrix and steel fibers, respectively, were developed based on the detected results of the evolution of the released strain energy and the strain at the notch tip. The proposed model was validated by comparing it with the models of fib Model Code 2010 and RILEM TC 162-TDF. The results show that the proposed model can reliably predict the strength, post softening or hardening branch, unloading and stiffness degradation of steel fiber reinforced concrete in uniaxial tension.

Characteristic analysis of acoustic emission monitoring parameters for crack propagation in UHPC-NC composite beam under bending test

Ultra high performance concrete (UHPC) has more outstanding mechanical properties and durability than normal concrete (NC) materials. Currently, analysis methods for the mechanical properties of UHPC structures and UHPC composite structures, such as measuring structural deflection, strain, and observing crack propagation, are relatively single. Acoustic emission (AE) technique is a non-destructive testing method that evaluates the damage state of structures effectively. The variation characteristics of AE parameters can be used to analyze the damage process and the failure precursor information of the structures. On this basis, AE technique was used to monitor the crack propagation of the UHPC-NC composite beam under four-point bending test in this study. Results showed that the U-shape UHPC layer gave full play to its high strength and ductility characteristics under bending, which was mainly manifested in reducing the number and width of cracks of the UHPC-NC composite beam, reducing the mid-span deflection and increasing the cracking load (Pcr) and ultimate load (Pu). AE ringing counts, energy, and b-value showed different and easily distinguishable variation characteristics at each failure stage of UHPC-NC composite beam and can be considered the optimal AE monitoring parameters. RA-AF association analysis can be used to further analyze the failure mode of UHPC-NC composite beam. AE monitoring method can be considered an alternative to traditional monitoring methods for the real-time monitoring of crack propagation in UHPC-NC composite beams.

Evaluation of the acoustic emission monitoring method for stress corrosion cracking on aboveground storage tank floor steel

Stress corrosion cracking (SCC), which is one of the main threats to the structural integrity of aboveground storage tanks (ASTs), has recently attracted much attention. In this paper, the SCC of the storage tank floor was studied by the acoustic emission (AE) and electrochemical methods. Throughout the whole SCC process, the AE signal characteristic parameters, cumulating features, and correlations were analyzed, and the signal time-frequency local features were extracted via wavelet packet analysis based on the MATLAB program. A good correlation of the instantaneous variations between the AE activity and the corrosion behavior was found. Microcrack creeping and macrocrack propagation were the most important AE sources in SCC; these sources can be recognized by the AE parameters and the AE frequency spectrum. The results in this paper will be beneficial for the diagnosis of corrosion severity and the recognition of the corrosion sources by AE online inspection and will further provide an assessment of the AST integrity by means of a risk-based inspection technique.

A novel acoustic emission monitoring method of cross-section precise localization of defects and wire breaking of parallel wire bundle

The monitoring and localization of defects and wire breaking of bridge cable are vital to the safe operation of the whole bridge. In this work, an innovative monitoring method that uses waveguides to draw out the steel wires at the end of the cable is proposed. This monitoring method can effectively capture the acoustic emission (AE) signal produced by defects and wire breaking of the cable. The transverse position of the wire breaking can also be accurately located so as to provide basis for the decision making of maintenance department. The pencil-lead breaks (PLB) test method is utilized to investigate the influence of the transition modes between the waveguide and the sensor and the connection modes between the waveguide and the cone on the AE signal. The PLB test and tensile test method are utilized to examine the AE signal characteristics of different sensors at the end of steel wires. Results showed that the cone transition between the waveguide and the sensor and the welding connection between waveguide and cone exhibit the minimum effect on AE waveform and parameters, such as amplitude, compared with that of the reference sensor without waveguide. In the tensile test, the transverse position of the wire breaking cannot be identified by analyzing the AE signals collected by each senor when the wire breaks, whereas it can be identified in the process of defects before the wire breaks.

Experimental research on bond behavior of reinforced recycled aggregate concrete based on the acoustic emission technique

This paper reports the experimental studies of the bond between recycled aggregate concrete (RAC) and ribbed steel bars, using the acoustic emission (AE) technique. Four different recycled aggregate replacement ratios (0%, 50%, 60%, and 70%) were considered in pullout tests. The test results indicate that the strength of the bond between RAC and ribbed bars is highly correlated to the RAC strength; the highest RAC bond strength was measured for the recycled aggregate replacement ratio of 60%. The conducted AE signal analysis included AE hits and energy analysis, positioning of AE events, AE signal average frequency analysis, b-value analysis, and RA-AF association analysis. The analysis results demonstrate that the internal damage of RAC is more severe and more dispersed both in space and in time owing to the initial defect of the recycled aggregate. Using the AE monitoring method, the dependence of the RAC bond failure mechanism on the recycled aggregate replacement ratio is explained.

Effect of different parameters on grinding efficiency and its monitoring by acoustic emission

Grinding efficiency is one of the most important considerations in the selection of grinding operation conditions because it has a significant impact on the productivity, quality, energy consumption and cost. Focusing on the core issues of grinding process, the paper presents some fundamental research findings in relation to grinding material removal mechanisms. The grinding efficiency is analysed by considering the rubbing, ploughing and cutting of a single-grit grinding. By analysing the features of acoustic emission in single-grit grinding tests, an evidence-based scientific foundation has been established for monitoring grinding efficiency using acoustic emission. Following the discussion of the energy consumption, temperature elevation and thermal stresses in grinding, the paper provides a logical depiction that explains why acoustic emission can be used for grinding thermal performance monitoring. As a result, a novel acoustic emission monitoring method is to monitor grinding temperature and grinding wheel wear status.

Crack source location by acoustic emission monitoring method in RC strips during in-situ load test

Various monitoring techniques are now available for structural health monitoring and Acoustic Emission (AE) is one of them. One of the major advantages of the AE technique is its capability to locate active cracks in structural members. AE crack locating approaches are affected by the signal attenuation and dispersion of elastic waves due to inhomogeneity and geometry of reinforced concrete (RC) members. In this paper, a novel technique is described based on signal processing and sensor arrangement to process multisensory AE data generated by the onset and propagation of cracks and is validated with experimental results from an in-situ load test. Considering the sources of uncertainty in the AE crack location process, a methodology is proposed to capture and locate events generated by cracks. In particular, the relationship between AE events and load is analyzed, and the feasibility of using the AE technique to evaluate the cracking behavior of two RC slab strips during loading to failure is studied.

A grinding acoustic emission monitoring method using wavelet transforms and fuzzy logic

It is known that the acoustic emission (AE) signals contain potentially valuable information for grinding wheel and work conditions during automatic grinding process. However, AE signals produced in the grinding zone are usually much more complicated and it is difficult to obtain enough effective information directly from raw AE signals. This paper presents an efficient grinding AE monitoring method based on a combination of wavelet transforms and fuzzy Logic techniques. First, the discrete wavelet transforms are used to extract the feature vectors from AE signals with different grinding wheel and work states. Secondly, a fuzzy classifier is employed to build a nonlinear relationship between the feature vectors of AE signals and the various grinding states. This method requires less computation and has a low sensitivity to the changes of grinding conditions. Experiment results show that the proposed intelligent monitoring system can identify the different grinding wheel and work states accurately and is valuable for industrial applications.

Evaluation of Finger-jointed Laminae for Glulam Timber by Acousitic Emission II Development of Evaluation System for Finger-jointed Laminae with Starved Joints

The laminae that comprise glulam timber are generally finger–jointed. However, laminae with starved joints in the finger–joint are occasionally found in the manufacture of glulam timber, and greatly decrease the timbers’ strength. Therefore, for the manufacture of glulam timber with good strength properties, the evaluation of finger–joint properties after finger–jointing is important, and the method is hoped to be simple and non–destructive. In our previous studies, we paid attention to acoustic emission (AE) as a non–destructive method, and bending test for finger–joint laminae with starved joints was performed. We clarified that AE generated during the bending test was promising for the detection of starved joints in the finger–joint at the early stage of the bending test. In addition, it became clear that the position of starved joints in finger–joint could be presumed by one– dimensional method of using AE signal (Ohuchi et al., 2004: Yano et al., 2007). Furthermore, in consideration of installing the AE monitoring method into the production line of the finger–joint laminae, a special attachment (jig) for the AE sensor installed into the production line was developed. From the result of verification test with the jig, it was clear that the possibility of the detection of the starved joints by AE as a non–destructive method was suggested in the case of loading to the finger–jointed part of laminae in 4 kN as the detection load with the jig (Ohuchi et al., 2009). However, it was pointed out that this method with the jig was not efficient for the following two reasons; first, it is difficult to set the position of the jig beforehand because neither the position nor the number of finger–joint parts in the laminae is decided. Secondly, it is necessary to stop the production line for the bending process. In this study, the main objective was to develop the evaluation method for detecting of the laminae with starved joints without stopping the production line regardless of both the position and the number of finger– joint parts in the laminae. In this report, the new type attachment (jig) which installed the AE sensor as non– destructive method for the detection of the laminae with starved joints is designed, and the evaluation tests of finger–jointed laminae were conducted by using this jig. That is, the evaluation system which installed the new Evaluation of Finger–jointed Laminae for Glulam Timber by Acoustic Emission II Development of Evaluation System for Finger–jointed Laminae with Starved Joints

Head-to-Head Comparison of 3-D Navigator Gated Magnetic Resonance Imaging and 16-Slice Computed Tomography to Detect Coronary Artery Stenosis in Patients

Acoustic emission (AE) monitoring is a powerful procedure used to detect and locate damage in mechanically loaded structures, materials and components. This chapter shows the capability of a new data processing system based on wireless AE equipment that is very useful for long-term monitoring of concrete and masonry structures. Systems based on wireless transmission should be cost efficient, easy to install and adaptive to different types of structures and infrastructures. To this purpose, computer-based procedures are implemented. These procedures are performed by automatic AE data processing and used to evaluate the AE data in laboratory tests and in situ monitoring. The final output of the code returns a description, as complete as possible, of damage patterns and their evolution of the monitored structure. In the most critical cases, or in some cases requiring in situ, long observation periods, the AE monitoring method is fine-tuned for a telematics processing procedure of AE data clouds. Finally, in order to increase the safety of structures and infrastructural networks, the proposed AE monitoring system could also be used to determine the seismic risk of civil constructions and monuments subjected to earthquakes.

Screening for Abdominal Aortic Aneurysm: Recommendation Statement

Acoustic emission (AE) monitoring is a powerful procedure used to detect and locate damage in mechanically loaded structures, materials and components. This chapter shows the capability of a new data processing system based on wireless AE equipment that is very useful for long-term monitoring of concrete and masonry structures. Systems based on wireless transmission should be cost efficient, easy to install and adaptive to different types of structures and infrastructures. To this purpose, computer-based procedures are implemented. These procedures are performed by automatic AE data processing and used to evaluate the AE data in laboratory tests and in situ monitoring. The final output of the code returns a description, as complete as possible, of damage patterns and their evolution of the monitored structure. In the most critical cases, or in some cases requiring in situ, long observation periods, the AE monitoring method is fine-tuned for a telematics processing procedure of AE data clouds. Finally, in order to increase the safety of structures and infrastructural networks, the proposed AE monitoring system could also be used to determine the seismic risk of civil constructions and monuments subjected to earthquakes.

Sirolimus-eluting vs. uncoated stents for prevention of restenosis in small coronary arteries: A randomized trial

Acoustic emission (AE) monitoring is a powerful procedure used to detect and locate damage in mechanically loaded structures, materials, and components. This chapter presents the capability of a new data processing system based on wireless AE equipment that is very useful for long-term monitoring of concrete and masonry structures. Systems based on wireless transmission should be cost-efficient, easy to install, and adaptive to different types of structures and infrastructures. To this purpose, computer-based procedures are implemented. These procedures are performed by automatic AE data processing and used to evaluate the AE data in laboratory tests and in situ monitoring. The final output of the code returns a description, as complete as possible, of damage patterns and their evolution of the monitored structure. In the most critical cases, or in some cases requiring in situ, long observation periods, the AE monitoring method is fine-tuned for a telematics processing procedure of AE data clouds. Finally, to increase the safety of structures and infrastructural networks, the proposed AE monitoring system could also be used to determine the seismic risk of civil constructions and monuments subjected to earthquakes.

Plasma surfactant protein-B: A novel biomarker in chronic heart failure (HF)

Acoustic emission (AE) monitoring is a powerful procedure used to detect and locate damage in mechanically loaded structures, materials and components. This chapter shows the capability of a new data processing system based on wireless AE equipment that is very useful for long-term monitoring of concrete and masonry structures. Systems based on wireless transmission should be cost efficient, easy to install and adaptive to different types of structures and infrastructures. To this purpose, computer-based procedures are implemented. These procedures are performed by automatic AE data processing and used to evaluate the AE data in laboratory tests and in situ monitoring. The final output of the code returns a description, as complete as possible, of damage patterns and their evolution of the monitored structure. In the most critical cases, or in some cases requiring in situ, long observation periods, the AE monitoring method is fine-tuned for a telematics processing procedure of AE data clouds. Finally, in order to increase the safety of structures and infrastructural networks, the proposed AE monitoring system could also be used to determine the seismic risk of civil constructions and monuments subjected to earthquakes.

Electrocardiographic features of arrhythmogenic right ventricular dysplasia/cardiomyopathy according to disease severity. A need to broaden diagnostic criteria

Acoustic emission (AE) monitoring is a powerful procedure used to detect and locate damage in mechanically loaded structures, materials and components. This chapter shows the capability of a new data processing system based on wireless AE equipment that is very useful for long-term monitoring of concrete and masonry structures. Systems based on wireless transmission should be cost efficient, easy to install and adaptive to different types of structures and infrastructures. To this purpose, computer-based procedures are implemented. These procedures are performed by automatic AE data processing and used to evaluate the AE data in laboratory tests and in situ monitoring. The final output of the code returns a description, as complete as possible, of damage patterns and their evolution of the monitored structure. In the most critical cases, or in some cases requiring in situ, long observation periods, the AE monitoring method is fine-tuned for a telematics processing procedure of AE data clouds. Finally, in order to increase the safety of structures and infrastructural networks, the proposed AE monitoring system could also be used to determine the seismic risk of civil constructions and monuments subjected to earthquakes.

Machine acoustic emission monitoring method — using pattern recognition procedure to develop soft models used as templates to detect fluctuations : European Patent No. 317,322 (24 May 1989)

Machine acoustic emission monitoring method — using pattern recognition procedure to develop soft models used as templates to detect fluctuations : European Patent No. 317,322 (24 May 1989)

Overview of acoustic emission monitoring of rock structures

Overview of Acoustic Emission Monitoring of Rock Structures The acoustic emission technique for monitoring the stability of rock masses in mines was initiated in the late 1930's by Obert and Duvall in the U. S. A. and Hodgson in Canada. The technique, called microseismic monitoring at that time and even to the present, is currently being extended beyond mining into a wide variety of Civil Engineering oriented problems. These include: Monitoring of all types of stressed rock masses in addition to mines (the subject of this paper). Monitoring of a wide variety of soil masses (dams, embankments, foundations, etc.). Monitoring of seepage and grout flow in both rock and soil. Determining in-situ stress history of rock and soil. Monitoring of steel highway bridges and offshore platforms. Monitoring of concrete bridges, dams and buildings. Assessing stability of permanent and temporary anchors, wire rope and other components of larger structural systems. While most of these activities are still in some form of development, they are generally beyond feasibility and are in various stages of implementation. This paper describes the acoustic emission monitoring method as pertains to rock monitoring and some of the directions that equipment manufacturers are currently pursuing. It then briefly describes applications of the method in connection with the monitoring of rock structures.