The Influence of Transmission Direction and the Natural Frequency of Transducers during the Testing of Silica Refractory Bricks by the Ultrasonic Pulse Method

2021 ◽  
Vol 57 (2) ◽  
pp. 96-104
Author(s):  
J. Brozovsky ◽  
L. Bodnarova
2021 ◽  
pp. 15-23
Author(s):  
Иржи Брожовский ◽  
Ленка Боднарова

Evaluating the quality of refractory materials is one of the important stages of production before these materials are handed over to the customer. One of the required parameters is to evaluate ultrasonic pulse velocity, as determined by measurements performed via the ultrasonic pulse method. Are presents findings on the influence of the direction of transmission and the natural frequency of transducers on ultrasonic pulse method measurements of silica refractory bricks. The findings reveal that the measurement requirements specified in standards for other building materials cannot be fully applied in the case of silica refractory bricks, and the assumption that ultrasonic pulse velocity increases with shorter measuring bases is not confirmed. The highest ultrasonic pulse velocities were measured during transmission across the width of the product, while the lowest velocities were measured over the thickness of the sample. In order to evaluate the quality of silica refractory bricks, it is necessary to unambiguously determine a uniform measuring base for transmission so as to ensure the reproducibility of the measurements performed by different laboratories.


2018 ◽  
pp. 31-35
Author(s):  
Ya. Serikov

Ensuring the reliability of buildings, structures, analysis of their structural elements during reconstruction or major repair includes the task of determining the physical and mechanical characteristics of materials — strength, homogeneity, evaluation of structural heterogeneity, the presence of microcracks, etc. In solving this problem, an ultrasonic pulse method of non-destructive quality control is used. The basis of the method is the dependence of the parameters of ultrasonic oscillations, on these characteristics when they pass through the material. As the main parameter of the information ultrasonic signal, the time of its passage from the radiating to the receiving ultrasonic transducers is used. The amplitude of the information ultrasonic signal to a large extent depends on the structure of the investigated material, its acoustic resistance. At significant violations of the structure of the material there is a significant decrease in the amplitude of the information signal, which causes an increase in the error of measuring the time of its passage, and hence the definition of characteristics, quality of the investigated material. The article describes the developed method of increasing the accuracy of measuring the time of passage of the ultrasonic signal from the radiating to the receiving ultrasonic transducers. The essence of the technique is to use the mathematical modeling of the shape of the ultrasound signal, in particular the form of its so-called «first introduction».


2014 ◽  
Vol 897 ◽  
pp. 139-143 ◽  
Author(s):  
Jiří Brožovský ◽  
Ámos Dufka

Modulus of elasticity of building materials can be determined in a static way (loading in a press) or by means of non-destructive test methods (ultrasonic pulse method and resonance method); the parameter is most frequently determined for concrete and both methods of determining elasticity modulus are codified in Standards. Elasticity characteristics of calcium silicate bricks were determined by means of resonance test method. Because the shape of calcium silicate bricks (a block with oblong foot) is different from the shape of test specimens for concrete (usually blocks with square foot), expected frequencies for verification of accuracy of measurement by resonance method were determined. Moisture content of calcium silicate bricks (water absorbing capacity is up to 12-14%) has influence on the value of resonance frequency. Difference between dynamic Young's modulus of elasticity from fundamental longitudinal and transverse resonant frequency is on average 2.8%.


1969 ◽  
Vol 2 (4) ◽  
pp. 275-284 ◽  
Author(s):  
R. Jones ◽  
I. Fącąoaru

2016 ◽  
Vol 722 ◽  
pp. 260-266
Author(s):  
Jiří Brožovský

Measuring with ultrasonic pulse method is influenced by various factors, like loading in particular inner tension when material built in a construction is tested. The paper researches influence of inner tension (load) on testing of calcium silicate bricks with ultrasonic pulse method. Calcium silicate bricks were loaded with force corresponding to 0 % (unloaded test specimens), 10 %, 20 %, 50 %, 60 % of ultimate compressive strength with various content of humidity (dried samples, w=2 %, w=8 % and samples saturated with water). It was found that ultrasonic pulse velocity is not considerably influenced at load of 10% and 20% of ultimate strength of bricks. However, ultrasonic pulse velocity considerably decreases after loading at 50% and 60% of ultimate compressive strength. Most of theoretical assumptions concerning mentioned concrete stated in technical literature were confirmed, however, particular values were different because of differences between concrete and calcium silicate bricks.


2018 ◽  
Vol 15 ◽  
pp. 99-103 ◽  
Author(s):  
Iva Rozsypalová ◽  
Michal Vyhlídal ◽  
Richard Dvořák ◽  
Tomáš Majda ◽  
Libor Topolář ◽  
...  

In this paper, the attention is paid to the investigation of the influence of high temperature acting on specimens made from specially designed cement-based composite. The experimental programme was carried out on six sets of beam specimens with the dimensions of 20 × 40 × 200 mm. The specimens were loaded to a pre-set temperature of 100, 200, 400, 600, 800 and 1000 °C and then the temperature was kept for 60 minutes. When the temperature loading had been done, the specimens were left to cool down to the ambient temperature. After that, the ultrasonic pulse method was used to determine the degree of damage of temperature loaded specimens. The measured data obtained by this non-destructive method are in high correlation with values of informative compressive strength of the composite obtained after the temperature loading of specimens.


2013 ◽  
Vol 284-287 ◽  
pp. 1315-1319 ◽  
Author(s):  
Jiří Brožovský ◽  
Lenka Bodnárová ◽  
Rudolf Hela ◽  
Rostislav Drochytka ◽  
Vlastimil Hela

Ultrasonic pulse method is a non-destructive testing method used for testing materials. For concrete, it is used mostly for determination of dynamic elasticity modulus, compressive strength, homogeneity, to determine depth of cracks or as a supportive method for testing frost resistance. Applicability of using ultrasonic pulse method for evaluation of degradation of concrete exposed to high temperature was proved. This method is unambiguously utilizable for rationalization of experimental work focused on optimization of composition of concrete resistant to high temperatures. Ultrasonic pulse method can be also used for mapping the degree of degradation of concrete elements and structures, which can be measured by means of direct sounding. Appropriateness of the use of ultrasonic pulse method for evaluation of degradation of concrete exposed to high temperature was proved. This method is unambiguously applicable for rationalization of experimental work focused on optimization of composition of concrete resistant to high temperatures. Ultrasonic pulse method can be also used for mapping degree of degradation of concrete elements and structures, which can be measured by means of direct sounding.


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