Abstract Acoustic Emission Monitoring Research Articles

Identification of fatigue damage evaluation using entropy of acoustic emission waveform

Acoustic emission (AE) is a passive nondestructive testing (NDT) technique which is employed to identify critical damage in structures before failure can occur. Currently, AE monitoring is carried out by calculating the features of the signal received by the AE sensor. User-defined acquisition settings (i.e., timing and threshold) significantly affect many traditional AE features such as count, energy, centroid frequency, rise time and duration. In AE monitoring, AE features are strongly related to the damage sources. Therefore, AE features that are calculated due to inaccurate user-defined acquisition settings can result in inaccurately classified damage sources. This work presents a new feature of the signal based on the measure of randomness calculated using second-order Renyi’s entropy. The new feature is computed from its discrete amplitude distribution making it independent of acquisition settings. This can reduce the need for human judgement in measuring the feature of the signal. To investigate the effectiveness of the presented feature, fatigue testing is conducted on an un-notched steel sample with simultaneous AE monitoring. Digital image correlation (DIC) is measured alongside AE monitoring to correlate both monitoring methods with material damage. The results suggest that the new feature is sensitive in identifying critical damages in the material.

Dynamic loading in monitoring of brittle objects by acoustic emission method

Acoustic emission monitoring requires applying a force to an object. In most cases, special-purpose loading devices are used for this process; however, they are subject to some operational limitations. Dynamic loading of a controlled object makes it unnecessary to use loading devices and put the object out of operation. The purpose of the study is to develop a technique of acoustic emission monitoring under dynamic loading. The paper describes results of experiments with impact loading of a glass sheet with a crack. It proposes a method for separating the total flow of acoustic emission signals into stationary groups that are typical for different acoustic emission sources.

Acoustic Emission Localization in Testing of Composite Structures

Acoustic emission (AE) is current trend of non-destructive monitoring methods. It suits perfectly for supporting of fatigue tests. The method is also applicable in monitoring of quasi-static tests. AE helps the engineers to understand the degradation process in the tested object and also keep track of the failures. This article offers an insight into the practical experience with acoustic emission. Tests of three different composite structures (wing, fuselage and hull panel) were chosen to illustrate the application of AE monitoring system during fatigue and quasi-static tests. These tests have shown that accuracy of localization is sufficient to identify damaged areas. Moreover, the system may offer an early warning of upcoming failure.

Acoustic Emission on Adhesively Bonded Single-Lap Joints of Composite Laminate during Tensile Test

Acoustic emission (AE) was used to monitor the tensile test of composites with adhesive specimens. The mechanical response behavior, damage and failure characteristics, and the corresponding AE characteristics of the composites have been investigated. The results show that the load of the join with defect in the adhesive layer is lower than the join with no defect. The higher AE relative energy and the AE amplitude were obtained in the adhesive specimen with defect in the adhesive layer whereas the variation of the AE relative energy is different from the adhesive specimen with on defect. The characteristics such as AE amplitude distribution, relative energy and cumulative hits are connected with the tensile damage and failure of the adhesively bonded single-lap joints of composite laminate. In the actual AE monitoring, these feature parameters should be considered entirely assess the damage and failure of the composites structures.

Acoustic Emission for Tank Bottom Monitoring

Acoustic Emission (AE) monitoring is an effective tool for prioritising more conventional non-destructive inspections of above ground tanks, either process or storage vessels. Results obtained from AE monitoring may be assessed against an existing data bank permitting plant management to prioritise maintenance to tanks with high active corrosion rates or leaks. AE results may be used to extend inspection periods of tanks without leaks or active corrosion.This paper briefly covers the theory of AE leak detection and corrosion monitoring including some background research into the difference between AE from corrosion and leaks. It looks at the equipment used and provides a summary of tank test results conducted by ATTAR and other overseas organisations as well as reviewing AE tank inspection economics.

Use of Acoustic Emission to Evaluate Residual Strength in FRP Pipes after Impact Damage

Acoustic Emission (AE) has proven to be a useful tool in the monitoring of fiberglass pressure vessels. The ASME Piping and Pressure Vessel Code (subsection X) implements AE as an approved method for quality control and in service testing of fiberglass pressure vessels, making it an accepted technique for the evaluation of fiber composite structures. This article presents the result of AE monitoring of fiber reinforced plastic (FRP) pipes after impact damage has incurred. The results from these tests indicate that AE can be used as a tool to predict the level of damage incurred in the pipes after impact and during pressurization. The use of the Felicity Ratio as the benchmark for evaluation is presented as the key evaluating value.

Acoustic Emission for Tank Bottom Monitoring

Acoustic Emission (AE) monitoring is an effective tool for prioritising more conventional non-destructive inspections of above ground tanks, either process or storage vessels. Results obtained from AE monitoring may be assessed against an existing data bank permitting plant management to prioritise maintenance to tanks with high active corrosion rates or leaks. AE results may be used to extend inspection periods of tanks without leaks or active corrosion. This paper covers the theory of AE leak detection and corrosion monitoring including some background research into the difference between AE from corrosion and leaks. It looks at the equipment used and provides a summary of tank test results conducted by ATTAR and other overseas organisations as well as reviewing AE tank inspection economics.