scholarly journals Analysis of the Frequency of Acoustic Emission Events in Terms of the Assessment of the Reduction of Mechanical Parameters of Cellulose–Cement Composites

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5882
Author(s):  
Anna Adamczak-Bugno ◽  
Aleksandra Krampikowska ◽  
Grzegorz Świt
Keyword(s):  
Acoustic Emission ◽  
Maximum Load ◽  
Cement Composites ◽  
Mechanical Parameters ◽  
Acoustic Emission Method ◽  
Flexural Stress ◽  
Emission Method ◽  
Load Action ◽  
Operational Factors ◽  
Maximum Stresses

The article proposes the application of the acoustic emission method as a technique for the evaluation of mechanical parameters of cellulose–cement composites. The analysis focused on frequency values in a time series analysis of elements subject to three-point flexural stress. In the course of a statistic analysis, it has been demonstrated that a significant reduction of the recorded frequency values is associated with a considerable reduction in strength. This allowed the authors to determine the range of frequencies related to the depreciation in the strength of an element. The tests were carried out on elements cut from a full-size cellulose–cement board. Samples exposed to potential operational factors (environmental and exceptional) were analysed. It was shown that the frequencies recorded before reaching the maximum load during bending of samples exposed to environmental factors (water and low temperature) were significantly different (were much lower) from the sounds emitted by elements subjected to exceptional factors (fire and high temperature). Considering the fact that the analysed frequencies of acoustic emission events occur before the maximum stresses in the material are reached and the elements are destroyed, this provides the basis for the use of the acoustic emission method to assess the condition of cellulose–cement composites in terms of lowering mechanical parameters by observing the frequency of events generated by the material during load action. It was found that generating by material frequencies above 300 kHz during bending does not result in a significant decrease in mechanical parameters. The emission of signals with frequencies ranging from 200 to 300 kHz indicate that there was a decline in strength exceeding 25% but less than 50%. The registration of signals with frequencies below 200 kHz indicates that the reduction in mechanical parameters was greater than 50%.

scholarly journals Fibre-Cement Panel Ventilated Façade Smart Control System

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 5076 ◽  
Author(s):  
Anna Adamczak-Bugno ◽  
Grzegorz Świt ◽  
Aleksandra Krampikowska
Keyword(s):  
Acoustic Emission ◽  
Control System ◽  
Material Structure ◽  
Signal Acquisition ◽  
Mechanical Parameters ◽  
Acoustic Emission Method ◽  
Emission Method ◽  
Smart Control ◽  
Fibre Cement ◽  
Ventilated Facade

This paper outlines a design for a fibre-cement panel ventilated façade smart control system based on the acoustic emission method. The paper also provides methodology and test results, as well as statistical analysis of the three-point bending results with AE signal acquisition as a basis for the development of the system in question. The test items were samples cut from a full-size fibre-cement panel for interior and exterior use, according to the standard guidelines. The recorded acoustic emission signals were classified statistically into four classes, which were assigned to the processes occurring in the material structure as a result of the applied load. The system development was based on the differences between the characteristics of the individual signal classes and their number for each test case, as well as on the different distribution of successive classes over time. Given the results of the tests and the resulting conclusions indicating the applicability of the acoustic emission method (based on signal classification using the k-means algorithm for the assessment of variations in the mechanical parameters of cement-fibre composites), a methodology for such assessment was therefore developed. The approach proposed is a reasonable method for assessing the variation in mechanical parameters of fibre-cement panels on the basis of the parameters determined by the non-destructive method indicated.

scholarly journals Monitoring of the Impact of Lithium Nitrate on the Alkali–aggregate Reaction Using Acoustic Emission Methods

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 20
Author(s):  
Justyna Zapała-Sławeta ◽  
Grzegorz Świt
Keyword(s):  
Acoustic Emission ◽  
Initial Reaction ◽  
Lithium Nitrate ◽  
Acoustic Emission Method ◽  
Emission Method ◽  
Acoustic Activity ◽  
Initial Stage ◽  
Chemical Admixture ◽  
Different Characteristics ◽  
The Impact

The study analyzed the possibility of using the acoustic emission method to analyse the reaction of alkali with aggregate in the presence of lithium nitrate. Lithium nitrate is a chemical admixture used to reduce adverse effects of corrosion. The tests were carried out using mortars with reactive opal aggregate, stored under the conditions defined by ASTM C227. The acoustic activity of mortars with a corrosion inhibitor was referred to linear changes and microstructure of specimens in the initial reaction stages. The study found a low acoustic activity of mortars with lithium nitrate. Analysis of characteristic parameters of acoustic emission signals, combined with the observation of changes in the microstructure, made it possible to describe the corrosion processes. As the reaction progressed, signals with different characteristics were recorded, indicating aggregate cracking at the initial stage of the reaction, followed by cracking of the cement paste. The results, which were referred to the acoustic activity of reference mortars, confirmed that the reaction of opal aggregate with alkali was mitigated in mortars with lithium nitrate, and the applied acoustic emission method enabled the detection and monitoring of ASR progress.

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.

Evaluation of Friction Phenomena of Brake Pads by Acoustic Emission Method

2014 ◽  
Vol 7 (2) ◽  
pp. 703-709 ◽  
Author(s):  
Kazuho Mizuta ◽  
Yukio Nishizawa ◽  
Koji Sugimoto ◽  
Katsuya Okayama ◽  
Alan Hase
Keyword(s):  
Acoustic Emission ◽  
Acoustic Emission Method ◽  
Emission Method ◽  
Brake Pads

scholarly journals Characterization of Fatigue Damage in 304L Steel by an Acoustic Emission Method

2013 ◽  
Vol 66 ◽  
pp. 651-660 ◽  
Author(s):  
A. Ould Amer ◽  
A.-L. Gloanec ◽  
S. Courtin ◽  
C. Touze
Keyword(s):  
Acoustic Emission ◽  
Fatigue Damage ◽  
Acoustic Emission Method ◽  
Emission Method ◽  
304L Steel
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