scholarly journals The influence of aggregate grain size on the parameters of acoustic emission signals obtained from a three-point bending test on concrete specimens degraded by high-temperatures

2018 ◽  
Vol 13 ◽  
pp. 1177-1182
Author(s):  
Libor Topolář ◽  
Šárka Keprdová ◽  
Luboš Pazdera
Keyword(s):  
Grain Size ◽  
Acoustic Emission ◽  
High Temperatures ◽  
Bending Test ◽  
Three Point Bending

Effect of Concrete Mixture Composition on Acoustic Emission and Fracture Parameters Obtained from Three-Point Bending Test

2015 ◽  
Vol 1100 ◽  
pp. 152-155
Author(s):  
Libor Topolář ◽  
Hana Šimonová ◽  
Petr Misák
Keyword(s):  
Acoustic Emission ◽  
Bending Test ◽  
Mixture Composition ◽  
Three Point Bending ◽  
Concrete Mixtures ◽  
Fracture Parameters ◽  
Fracture Tests ◽  
Stress Behaviour ◽  
Bending Fracture ◽  
Fracture Processes

This paper reports the analysis of acoustic emission signals captured during three-point bending fracture tests of concrete specimens with different mixture composition. Acoustic emission is an experimental tool well suited for monitoring fracture processes in material. The typical acoustic emission patterns were identified in the acoustic emission records for three different concrete mixtures to further describe the under-the-stress behaviour and failure development. An understanding of microstructure–performance relationships is the key to true understanding of material behaviour. The acoustic emission results are accompanied by fracture parameters determined via evaluation of load versus deflection diagrams recorded during three-point bending fracture tests.

Three-Point Bending Test Evaluation of Concrete Specimens by Non-Traditional Analysis of Acoustic Emission Method

2016 ◽  
Vol 837 ◽  
pp. 198-202
Author(s):  
Luboš Pazdera ◽  
Libor Topolář ◽  
Tomáš Vymazal ◽  
Petr Daněk ◽  
Jaroslav Smutny
Keyword(s):  
Acoustic Emission ◽  
Signal Analysis ◽  
Measurement Data ◽  
Bending Test ◽  
Test Evaluation ◽  
Acoustic Emission Method ◽  
Emission Method ◽  
Three Point Bending ◽  
Time Frequency ◽  
Emission Signal

The aim of the paper is focused on the analysis of the mechanical properties of the concrete specimens with plasticizer at three point bending test by the signal analysis of the acoustic emission signal. The evaluations were compared the measurement and the results obtained with theoretical presumptions. The Joint Time Frequency Analysis applied on measurement data and its evaluation is described. It is well known that the Acoustic Emission Method is a very sensitive method to determine active cracks into structure. However, evaluation of acoustic emission signals is very difficult. A non-traditional method was used to signal analysis of burst acoustic emission signals recorded during three point bending test.

The Assessment of High-Temperature Degraded Concrete Specimens of Different Mixtures by Acoustic Emission Method during Three-Point Bending Test and Pulse Velocity Method in Comparison with Destructive Tests

2017 ◽  
Vol 908 ◽  
pp. 88-93 ◽  
Author(s):  
Libor Topolář ◽  
Richard Dvořák ◽  
Luboš Pazdera
Keyword(s):  
Acoustic Emission ◽  
Building Materials ◽  
Pulse Velocity ◽  
Bending Test ◽  
Structural Components ◽  
Acoustic Emission Method ◽  
Emission Method ◽  
Three Point Bending ◽  
Live Loads ◽  
Non Destructive

One of the advantages of concrete over other building materials is its inherent fire-resistive properties. The concrete structural components still must be able to withstand dead and live loads without collapse even though the rise in temperature causes a decrease in the strength and modulus of elasticity for concrete and steel reinforcement. In addition, fully developed fires cause expansion of structural components and the resulting stresses and strains must be resisted. This paper reports the results of measurements by Acoustic Emission method during three-point bending test on concrete specimens. The Acoustic emission method is a non-destructive technique used widely for structural health monitoring purposes of structures. The sensors are mounted by beeswax on the surface of the material or structure to record the motion of the surface under the elastic excitation of the cracking sources. The concrete specimens were heated in a programmable laboratory furnace at a heating rate of 5 °C/min. The specimens were loaded at six temperatures, 200 °C, 400 °C, 600 °C, 800 °C, 1000 °C, and 1200 °C maintained for 60 minutes. The results are obtained in the laboratory.

Damage Pattern Recognition of Refractory Materials Based on k-Means Clustering Analysis

2012 ◽  
Vol 602-604 ◽  
pp. 990-994
Author(s):  
Xi Li ◽  
Zhi Gang Wang ◽  
Chang Ming Liu ◽  
Bing Qiang Han
Keyword(s):  
Pattern Recognition ◽  
Acoustic Emission ◽  
Clustering Analysis ◽  
Bending Test ◽  
Refractory Materials ◽  
Damage Pattern ◽  
Three Point Bending ◽  
Centroid Frequency ◽  
Acquisition Device ◽  
Microscopic Damage

The k-means algorithm was used to divide the acoustic emission signals collected during the three-point bending test into two types. Combining with the analysis of AE parameters can we distinguish the micro-damage pattern recognition of the refractory materials. The bending test equipment is HMOR/STRAIN, and the AE acquisition device is DISP from PAC. Amplitude, counts, risetime, duration and centroid frequency were selected as the AE parameters .The microscopic damage modes of the refractory materials were recognized.

scholarly journals Damage Assessment using Acoustic Emission on Concrete Beam

2020 ◽  
Vol 9 (3) ◽  
pp. 2977-2981
Keyword(s):  
Acoustic Emission ◽  
Damage Assessment ◽  
High Performance ◽  
High Performance Concrete ◽  
Bending Test ◽  
Ultra High Performance Concrete ◽  
Reliable Technique ◽  
Damage Level ◽  
Three Point Bending ◽  
Selection Of

The selection of reliable technique for damage assessment is important in civil engineering structure. The present study proposed Acoustic emission (AE) technique by using the fundamental AE parameter to evaluate damage accumulated on Ultra High-Performance Concrete (UHPC) specimens. The UHPC beam with dimension of 515 mm x 98 mm x 98 mm was tested under three-point bending test with stepwise flexural load. In order to detect and to collect the AE data, Micro-SAMOS (μ-SAMOS) digital AE system and R6I sensors type were used while data analyses were carried out using AEwin software. The damage level that take place during increasing static loading on tested concrete beams and the mechanism was successfully evaluated using the AE technique.

Correlation between Parameters of Acoustic Emission and Fracture Characteristics Obtained from Three-Point Bending Test

2015 ◽  
Vol 1124 ◽  
pp. 231-236
Author(s):  
Libor Topolář ◽  
Luboš Pazdera
Keyword(s):  
Acoustic Emission ◽  
Bending Test ◽  
Emission Method ◽  
Fracture Characteristics ◽  
Three Point Bending ◽  
Experimental Tool ◽  
Fracture Tests ◽  
Stress Behaviour ◽  
Bending Fracture ◽  
Fracture Processes

This paper reports the analysis of acoustic emission signals captured during three-point bending fracture tests of concrete specimens with different mixture composition. Acoustic emission method is an experimental tool well suited for monitoring fracture processes in material. The typical acoustic emission patterns were identified in the acoustic emission records for three different mixtures to further describe the under-the-stress behaviour and failure development. An understanding of microstructure–performance relationships is the key to true understanding of material behaviour. The acoustic emission results are accompanied by fracture parameters determined via evaluation of load versus deflection diagrams recorded during three-point bending fracture tests.

Evaluation of Acoustic Emission Events Generated at Three Point Bending of Different Concrete Specimens by Spectral Analysis

2016 ◽  
Vol 258 ◽  
pp. 485-488
Author(s):  
Lubos Pazdera ◽  
Libor Topolář ◽  
Petr Daněk ◽  
Jaroslav Smutny ◽  
Karel Mikulasek
Keyword(s):  
Acoustic Emission ◽  
Bending Test ◽  
Acoustic Emission Method ◽  
Emission Method ◽  
Direct Evaluation ◽  
Cement Ratio ◽  
Three Point Bending ◽  
Time Frequency ◽  
Frequency Domains ◽  
The Individual

The paper aims to the determine of the mechanical properties of the concrete specimens at three-point bending test by application of the Acoustic Emission Method. Recorded acoustic emission events generated during three-point loading have been chosen. Some frequency and joint time-frequency methods are applied to these records. Time series as acoustic emission events may be analyzed in the time, frequency, and/or time-frequency domains. The selection is based on the type of the signal in question, on the type of analysis to be used or the result achieved. In many applications, direct evaluation of the time-amplitude representation is neither easy nor advantageous. The individual mixtures were different in cement dosage and water-cement ratio based on how much the amount of cement was increased while maintaining consistency S2 according to EN 206.

Acoustic Emission Evaluation of Thermal Barrier Coatings Using the Three Point Bending Test

1991 ◽  
Author(s):  
A. T. J. Verbeek ◽  
J. M. Houben ◽  
J. A. Klostermann
Keyword(s):  
Acoustic Emission ◽  
Thermal Barrier Coatings ◽  
Light And Electron Microscopy ◽  
Wide Band ◽  
Bending Test ◽  
Thermal Barrier ◽  
Barrier Coatings ◽  
Bending Tests ◽  
Three Point Bending ◽  
Resonance Sensor

Thermal Barrier coatings were tested in three point bending tests, combined with acoustic emission evaluation. The test specimens consist of a 2 mm substrate with a 0.1 mm FeCrAlY bondcoat and a 0.3 mm ZrO2/Y2O3 93/7.8 weight % topcoat. Both the topcoat and the bondcoat were air plasma sprayed under varying conditions of the substrate cooling and the length of the plasma flame. On investigating the microstructure of the coatings, using light and electron microscopy, differences could be observed, due to the various spraying techniques. The coated specimens were tested in a tensile testing machine equiped with a special tool for three point bending tests. During bending, acoustic emissions from the coating were measured, using a two channel acoustic emission apparatus. Two types of AE sensors were used, namely a 150 kHz resonance sensor and a 0.1 −1 MHz wide band sensor. The various coatings show different AE patterns, especially the bondcoats which showed differences according to the spraying techniques. The use of wide band sensors had some advantages, however they were less sensitive than resonance sensors, they take signals that were received by the resonance ones. After testing, the specimens were prepared and microscopically investigated. Herewith it was possible to establish a relationship between the measured AE signal and the type of coating and coating failure.

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