scholarly journals EVALUATION OF STRENGTH PARAMETERS OF POLYMER COMPOSITES USED FOR DENTAL RESTORATION BY THE METHOD OF ACOUSTIC EMISSION

2021 ◽  
Vol 21 (3) ◽  
pp. 164-172
Author(s):  
V.F. Makeev ◽  
V.S. Kukhta ◽  
O.S. Kyrmanov ◽  
N.R. Kliuchkovska ◽  
V.R. Skalsky ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Mechanical Tests ◽  
Fracture Load ◽  
Dental Restoration ◽  
Measuring System ◽  
Dental Composites ◽  
Strength Parameters ◽  
Emission Data ◽  
Compression Load ◽  
Ae Signals

The aim of the study is to create a technique and perform mechanical tests to determine the strength parameters of dental composites from the standpoint of linear fracture mechanics, and using the phenomenon of acoustic emission to determine the origin and development of destruction of light-curing dental composites under quasi-static local compression load. The following hybrid dental composites of domestic and foreign manufacturers were selected for comparison: Latelux (Latus, Ukraine), TETRIC N-CERAM (Ivoclar Vivadent, Liechtenstein), CHARISMA CLASSIC (Kulzer, Germany). 10 disc samples of 13 mm diameter and 5 mm thick of each material were made by using a specially designed mould for study purposes. Packaging and moulding of the material into the mould was performed in laboratory conditions at an air temperature of 18 – 21°C. Before testing, the samples were kept for 24 hours at a temperature of 37°C in saline solution. The samples were loaded on the SVR-5 machine using a ball indenter. During the experiments, acoustic emission data were simultaneously recorded using the SKOP-8 measuring system. In the post-processing stage, the dependencies of the load change during the experiment, the distribution of the amplitudes of the registered AE signals and their sum over time were recorded. The fracture load, indenter displacement, and the features of composite fracture were determined from the obtained dependencies based on the analysis of AE generation under the load. Analysis of the parameters of the AE signals showed that during the destruction of the Tetric N-Ceram composite the signals had the largest amplitude and energy, and of Latelux had the smallest ones.

scholarly journals Comparative analysis of the strength of restoration polymers of light polymerization for dental restoration using the acoustic emission method: part one

2021 ◽  
Vol 107 (3) ◽  
pp. 26-32
Author(s):  
V. Kukhta ◽  
◽  
V. Makeev ◽  
O. Kyrmanov ◽  
V. Skalsky ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Comparative Analysis ◽  
High Energy ◽  
Dental Restoration ◽  
Acoustic Emission Method ◽  
Local Loading ◽  
Emission Method ◽  
Composite Failure ◽  
Initial Stage ◽  
Ae Signals

Purpose. Comparative analysis of the strength of hybrid restoration composites of light polymerization during their local loading using the phenomenon of acoustic emission. The following restoration composites were studied: Latelux, Tetric N-Ceram, Charisma Classic. Results. It was determined that the nature of the destruction of all composites is the same: elastic-plastic at the initial stage of the load with a transition to brittle as its further growth. Three types of composite failure are observed: correct, incorrect and mixed. The first predominated during fracture under the action of local loading of the Latelux composite, for Tetric N-Ceram and Charisma Classic materials a mixed type of fracture is characteristic. Conclusions. Analysis of the parameters of the AE signals showed that the signals had the highest amplitude and energy when the Tetric N-Ceram composite was destroyed, and the lowest – Latelux. All dental composites are dominated by high-energy ductile-brittle and brittle fracture, which indicates the spread of micro- and macrocracks of various sizes in materials. Key words: polymer composites, strength, acoustic emission method.

scholarly journals Calibration and Laboratory Testing of Computer Measuring System 8AE-PD Dedicated for Analysis of Acoustic Emission Signals Generated by Partial Discharges Within Oil Power Transformers

2017 ◽  
Vol 42 (2) ◽  
pp. 297-311 ◽  
Author(s):  
Franciszek Witos ◽  
Grzegorz Szerszeń ◽  
Zbigniew Opilski ◽  
Maciej Setkiewicz ◽  
Aneta Olszewska ◽  
...  
Keyword(s):  
Acoustic Emission ◽  
Steel Plate ◽  
Partial Discharges ◽  
Measuring System ◽  
Power Transformers ◽  
General Description ◽  
Emission Method ◽  
Peak Voltage ◽  
Limit Values ◽  
Ae Signals

Abstract In the paper, there are presented a general description of the constructed measuring system 8AE-PD, the results of calibration of this system by the Hsu-Nielsen method as well as the testing of the measuring system during recording signals generated by Hsu-Nielsen sources in a steel plate and a modeled partial discharge (PD) source. There is also presented the methodology of investigations by the calibrated acoustic emission method. The results of analyses of PD signals coming from the modeled sources are given. In particular, there are described the properties of acoustic emission (AE) signals generated by the PDs as well as the dependencies of the peak-to-peak voltage Umm, the RMS voltage Urms and the descriptors of acronyms ADP and ADC on the apparent charge Q introduced by the modeled PD source. There are determined the limit values of the apparent charge Q introduced by the modeled PD source for which the recorded signal is identified as originating from the PDS.

Investigation of the Stages of Damage Accumulation in Polymer Composite Materials

2019 ◽  
Vol 945 ◽  
pp. 515-521 ◽  
Author(s):  
O.V. Bashkov ◽  
A.A. Bryansky ◽  
I.V. Belova ◽  
Denis B. Solovev
Keyword(s):  
Acoustic Emission ◽  
Power Law ◽  
Experimental Studies ◽  
Amplitude Distribution ◽  
B Value ◽  
Bending Test ◽  
Emission Data ◽  
Three Point Bending ◽  
Destructive Processes ◽  
Ae Signals

This paper presents the results of the study of strength and fracture processes of FRP samples, obtained by vacuum and vacuum-autoclave molding methods. The experimental studies consisted of a three-point bending test with step loading, accompanied by an acoustic emission method. Based on the acoustic emission data recorded using the acoustic-emission software and hardware complex during the experiments, a method for estimating the accumulated damage using various techniques for analyzing acoustic emission parameters was tested. The results of methods for analyzing the power-law coefficient of accumulation of total AE, b-value and density distribution of amplitudes and median frequencies are considered. An estimate of the power-law coefficient of accumulation of the total AE made it possible to determine the bearing capacity of PCM samples. Using the techniques for analyzing the amplitude distribution of the AE signals and the distribution density of the amplitudes and median frequencies of the AE signals, destructive processes in the volume of samples were described and the stages of their damaging were revealed.

Research of the Damage and Failure Processes of Composite Materials Based on Acoustic Emission Monitoring and Method of Digital Image Correlation

2015 ◽  
Vol 243 ◽  
pp. 163-170 ◽  
Author(s):  
V.E. Wildemann ◽  
E.V. Spaskova ◽  
A.I. Shilova
Keyword(s):  
Acoustic Emission ◽  
Digital Image Correlation ◽  
Digital Image ◽  
Three Dimensional ◽  
Mechanical Tests ◽  
Image Correlation ◽  
Optimal Parameters ◽  
Emission Data ◽  
Frequency Distributions ◽  
Damage And Failure

The work presents an analysis of the methodical questions of the digital image correlation and acoustic emission application for studying damage accumulation process in composites. The research included tensile mechanical tests on flat samples with a hole. According to the acoustic emission data the localization graphs and the peak amplitude and frequency distributions were plotted. Additionally, the analysis of inhomogeneous deformation fields was made by non-contact three-dimensional digital optical system Vic-3D. The optimal parameters of post processing were selected.

scholarly journals Analysis of Acoustic Emission (AE) Signals for Quality Monitoring of Laser Lap Microwelding

2021 ◽  
Vol 11 (15) ◽  
pp. 7045
Author(s):  
Ming-Chyuan Lu ◽  
Shean-Juinn Chiou ◽  
Bo-Si Kuo ◽  
Ming-Zong Chen
Keyword(s):  
Stainless Steel ◽  
Acoustic Emission ◽  
Frequency Domain ◽  
Monitoring System ◽  
Welding Quality ◽  
Steel Sheets ◽  
Signal Features ◽  
Ae Signal ◽  
Laser Microwelding ◽  
Ae Signals

In this study, the correlation between welding quality and features of acoustic emission (AE) signals collected during laser microwelding of stainless-steel sheets was analyzed. The performance of selected AE features for detecting low joint bonding strength was tested using a developed monitoring system. To obtain the AE signal for analysis and develop the monitoring system, lap welding experiments were conducted on a laser microwelding platform with an attached AE sensor. A gap between the two layers of stainless-steel sheets was simulated using clamp force, a pressing bar, and a thin piece of paper. After the collection of raw signals from the AE sensor, the correlations of welding quality with the time and frequency domain features of the AE signals were analyzed by segmenting the signals into ten 1 ms intervals. After selection of appropriate AE signal features based on a scatter index, a hidden Markov model (HMM) classifier was employed to evaluate the performance of the selected features. Three AE signal features, namely the root mean square (RMS) of the AE signal, gradient of the first 1 ms of AE signals, and 300 kHz frequency feature, were closely related to the quality variation caused by the gap between the two layers of stainless-steel sheets. Classification accuracy of 100% was obtained using the HMM classifier with the gradient of the signal from the first 1 ms interval and with the combination of the 300 kHz frequency domain signal and the RMS of the signal from the first 1 ms interval.

scholarly journals Acoustic Emission Testing and Ib-Value Analysis of Ultraviolet Light-Irradiated Fiber Composites

2021 ◽  
Vol 11 (14) ◽  
pp. 6550
Author(s):  
Doyun Jung ◽  
Wonjin Na
Keyword(s):  
Acoustic Emission ◽  
Irradiation Time ◽  
Tensile Load ◽  
Failure Behavior ◽  
Value Analysis ◽  
Emission Testing ◽  
Final Failure ◽  
Acoustic Emission Testing ◽  
Woven Glass Fiber ◽  
Ae Signals

The failure behavior of composites under ultraviolet (UV) irradiation was investigated by acoustic emission (AE) testing and Ib-value analysis. AE signals were acquired from woven glass fiber/epoxy specimens tested under tensile load. Cracks initiated earlier in UV-irradiated specimens, with a higher crack growth rate in comparison to the pristine specimen. In the UV-degraded specimen, a serrated fracture surface appeared due to surface hardening and damaged interfaces. All specimens displayed a linearly decreasing trend in Ib-values with an increasing irradiation time, reaching the same value at final failure even when the starting values were different.

Acoustic Emission Monitoring of Leaks in Pipes for Transport of Liquid and Gaseous Media: A Model Experiment

2006 ◽  
Vol 13-14 ◽  
pp. 351-356 ◽  
Author(s):  
Andreas J. Brunner ◽  
Michel Barbezat
Keyword(s):  
Acoustic Emission ◽  
Model Experiment ◽  
Structural Integrity ◽  
Fiber Composite ◽  
Leak Testing ◽  
Pipe Segment ◽  
Potential Applications ◽  
Gaseous Media ◽  
The Media ◽  
Ae Signals

In order to explore potential applications for Active Fiber Composite (AFC) elements made from piezoelectric fibers for structural integrity monitoring, a model experiment for leak testing on pipe segments has been designed. A pipe segment made of aluminum with a diameter of 60 mm has been operated with gaseous (compressed air) and liquid media (water) for a range of operating pressures (between about 5 and 8 bar). Artificial leaks of various sizes (diameter) have been introduced. In the preliminary experiments presented here, commercial Acoustic Emission (AE) sensors have been used instead of the AFC elements. AE sensors mounted on waveguides in three different locations have monitored the flow of the media with and without leaks. AE signals and AE waveforms have been recorded and analysed for media flow with pressures ranging from about 5 to about 8 bar. The experiments to date show distinct differences in the FFT spectra depending on whether a leak is present or not.

scholarly journals A Principal Component Analysis of Acoustic Emission Signals from a Landing Gear Component

2008 ◽  
Vol 13-14 ◽  
pp. 41-47 ◽  
Author(s):  
Rhys Pullin ◽  
Mark J. Eaton ◽  
James J. Hensman ◽  
Karen M. Holford ◽  
Keith Worden ◽  
...  
Keyword(s):  
Principal Component Analysis ◽  
Acoustic Emission ◽  
Background Noise ◽  
Principal Component ◽  
Component Analysis ◽  
Landing Gear ◽  
Fracture Detection ◽  
Artificial Fracture ◽  
High Level ◽  
Ae Signals

This work forms part of a larger investigation into fracture detection using acoustic emission (AE) during landing gear airworthiness testing. It focuses on the use of principal component analysis (PCA) to differentiate between fracture signals and high levels of background noise. An artificial acoustic emission (AE) fracture source was developed and additionally five sources were used to generate differing AE signals. Signals were recorded from all six artificial sources in a real landing gear component subject to no load. Further to this, artificial fracture signals were recorded in the same component under airworthiness test load conditions. Principal component analysis (PCA) was used to automatically differentiate between AE signals from different source types. Furthermore, successful separation of artificial fracture signals from a very high level of background noise was achieved. The presence of a load was observed to affect the ultrasonic propagation of AE signals.

Grinding Acoustic Emission Classification in Terms of Mechanical Behaviours

2007 ◽  
Vol 329 ◽  
pp. 15-20 ◽  
Author(s):  
Xun Chen ◽  
James Griffin
Keyword(s):  
Neural Network ◽  
Acoustic Emission ◽  
Material Removal ◽  
Grinding Process ◽  
Short Time Fourier Transform ◽  
Fundamental Investigation ◽  
Mechanical Behaviours ◽  
Wavelets Transform ◽  
Short Time ◽  
Ae Signals

The material removal in grinding involves rubbing, ploughing and cutting. For grinding process monitoring, it is important to identify the effects of these different phenomena experienced during grinding. A fundamental investigation has been made with single grit cutting tests. Acoustic Emission (AE) signals would give the information relating to the groove profile in terms of material removal and deformation. A combination of filters, Short-Time Fourier Transform (STFT), Wavelets Transform (WT), statistical windowing of the WT with the kurtosis, variance, skew, mean and time constant measurements provided the principle components for classifying the different grinding phenomena. Identification of different grinding phenomena was achieved from the principle components being trained and tested against a Neural Network (NN) representation.

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