일반적으로 내화물의 진동특성은 등방성 재료로 가정한 후 확인한다. 하지만 실제로 내화물은 특정 방향으로 가압 성형하여 제조되기 때문에 이방성 재료특성을 보인다. 따라서 본 연구에서는 내화물을 정방정계 대칭성으로 가정하고, 유한요소프로그램을 이용해 너비, 길이, 높이 방향에 대한 주파수 응답을 얻었다. 해석결과의 타당성은 실제 측정결과의 비교를 통해 검증하였다. 주파수 응답을 기반으로, 충격방향기법을 이용하여 내화벽돌의 세 방향의 두께를 추정하였다. 실험을 통해 찾은 두께와 실제 두께와의 최대 오차율은 5 % 미만으로 확인되었다. 이를 통해 내화물과 같은 이방성 재료 두께 측정 시 충격반향기법의 효용성을 확인하였다.
일반적으로 내화물의 진동특성은 등방성 재료로 가정한 후 확인한다. 하지만 실제로 내화물은 특정 방향으로 가압 성형하여 제조되기 때문에 이방성 재료특성을 보인다. 따라서 본 연구에서는 내화물을 정방정계 대칭성으로 가정하고, 유한요소프로그램을 이용해 너비, 길이, 높이 방향에 대한 주파수 응답을 얻었다. 해석결과의 타당성은 실제 측정결과의 비교를 통해 검증하였다. 주파수 응답을 기반으로, 충격방향기법을 이용하여 내화벽돌의 세 방향의 두께를 추정하였다. 실험을 통해 찾은 두께와 실제 두께와의 최대 오차율은 5 % 미만으로 확인되었다. 이를 통해 내화물과 같은 이방성 재료 두께 측정 시 충격반향기법의 효용성을 확인하였다.
Generally, the vibration characteristics of refractory ceramics are identified by assuming them as isotropic materials. However, in practice, refractory ceramics exhibit anisotropic properties as they are manufactured by pressing ceramic powders along a particular direction. Therefore, in this resea...
Generally, the vibration characteristics of refractory ceramics are identified by assuming them as isotropic materials. However, in practice, refractory ceramics exhibit anisotropic properties as they are manufactured by pressing ceramic powders along a particular direction. Therefore, in this research, the frequency responses of a refractory ceramic brick along its width, length, and height directions were acquired using finite element analysis by assuming that the ceramics had tetragonal symmetry in their material properties. The validity of the numerical analysis results was verified by comparing them with those from experimental measurements. Based on the frequency response, the thicknesses of the refractory brick along three different directions were estimated using the impact-echo technique. The maximum difference between the estimated and actual thicknesses was observed to be less than 5 %. This result confirms the effectiveness of the impact-echo technique along with anisotropic property characterization to evaluate the thickness of the refractory ceramic.
Generally, the vibration characteristics of refractory ceramics are identified by assuming them as isotropic materials. However, in practice, refractory ceramics exhibit anisotropic properties as they are manufactured by pressing ceramic powders along a particular direction. Therefore, in this research, the frequency responses of a refractory ceramic brick along its width, length, and height directions were acquired using finite element analysis by assuming that the ceramics had tetragonal symmetry in their material properties. The validity of the numerical analysis results was verified by comparing them with those from experimental measurements. Based on the frequency response, the thicknesses of the refractory brick along three different directions were estimated using the impact-echo technique. The maximum difference between the estimated and actual thicknesses was observed to be less than 5 %. This result confirms the effectiveness of the impact-echo technique along with anisotropic property characterization to evaluate the thickness of the refractory ceramic.
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제안 방법
After obtaining the anisotropic elastic stiffness matrix, a numerical modal analysis was conducted using the commercial FEA package PZFlex® to analyze the vibrational characteristics of the refractory brick, such as resonance frequencies and mode shapes.
However, in practice, refractory ceramics exhibit anisotropic properties as they are manufactured by pressing ceramic powder along a particular direction. In this research, the frequency responses of refractory ceramic bricks along the width, length, and height directions are acquired by considering tetragonal symmetry in the material properties of the refractory ceramics.
In this research, the vibration characteristics of the refractory brick were analyzed by considering the anisotropic properties of the material. The refractory brick was considered to have tetragonal structural symmetry.
The estimated thicknesses differed from the actual thicknesses by less than 5 %. This confirms the effectiveness of the impact-echo technique along with anisotropic property characterization to evaluate the thickness of the refractory brick. The procedure adopted in this study can be conveniently applied to the thickness estimation of other ceramic materials as well as isotropic materials.
대상 데이터
The instruments used in the experiment were an impact hammer (PCB Piezotronics 208A02), accelerometer (B&K 4367), and amplifier (Type 2692 by Bruel & Kjaer).
The sound velocities along the three directions were measured using the ultrasonic through-transmission technique. The instruments used were a pulser/receiver (Olympus Panametrics 5072PR), an oscilloscope (LeCroy LT322), and ultrasonic transducers (Olympus Panametrics NDT V103 and V153). The measurement was conducted by attaching a transmitting transducer and receiving transducer on the opposite planes of an aluminum plate that has dimensions of 300 mm (width) × 270 mm (length) × 20 mm (height), as shown in Fig.
The refractory brick characterized in this work is a standard carbon block (Nippon Electrode Company Ltd. Grade BC-5) whose density is 1,920 kg/m3. The impact-echo technique allows the measurement of the thickness of the brick based on the principle presented in Eq.
이론/모형
As stated in Eq. (1), it is necessary to know the sound velocity beforehand to estimate the thickness of a refractory brick using the impact-echo technique. Hence, the longitudinal and shear wave velocities of the refractory brick were measured.
and ultrasonic pulse-echo technique. In this work, the impact-echo technique is used to characterize the state of refractory ceramics in a blast furnace. The impact-echo technique was developed by Carino and Sansalone to inspect flaws in concrete or masonry.
The frequency response of a refractory brick that has the same dimensions as that used in the numerical analysis was measured experimentally using the impact-echo technique. The instruments used in the experiment were an impact hammer (PCB Piezotronics 208A02), accelerometer (B&K 4367), and amplifier (Type 2692 by Bruel & Kjaer).
The sound velocities along the three directions were measured using the ultrasonic through-transmission technique. The instruments used were a pulser/receiver (Olympus Panametrics 5072PR), an oscilloscope (LeCroy LT322), and ultrasonic transducers (Olympus Panametrics NDT V103 and V153).
[7] However, in case of refractory ceramics, no general acoustic properties are available, so it is necessary to determine the longitudinal wave velocities properties of a specific refractory sample of interest. Therefore, in this work, the longitudinal wave velocities of a refractory brick were measured along different crystal directions using the ultrasonic through-trans mission technique. The vibration characteristics of refractory bricks were then examined by using FEA (Finite Element Analysis).
성능/효과
Thus, the sound velocity along the Z direction was likely to be different from that along the other two directions. In the experiment, the longitudinal wave velocities V11, V22, and V33 along the X, Y, and Z directions were measured to be 2981, 2954, and 2662 m/s, respectively. The shear wave velocities V44, V55, and V66 on the YZ, XZ, and XY planes were 1796, 1801, and 1903 m/s, respectively.
According to previous studies, this extent of agreement has not been possible because all the previous studies have assumed that the refractory material has isotropic properties.[4,5]Therefore, it was concluded that we could accurately estimate the thickness of a refractory brick using the impact-echo technique with measurement errors not exceeding 4.7 %. However, the measurement error in the Z direction is considerably high when compared with that in the X and Y directions.
참고문헌 (28)
A. N. Dmitriev, Y. A. Chesnkov, K. Chen, and O. Y. Ivanov, "Monitoring the wear of the refractory lining in the blast furnace hearth," Steel in Translation 43, 8-14 (2013).
S. N. Silva, F. Vernilli, S. M. Justus, O. R. Marques, A. Mazine, J. B. Baldo, E. Longo, and J. A. Varela, "Wear mechanism for blast furnace hearth refractory lining," Ironmaking & Steelmaking 32, 459-467 (2005).
C. Y. Wang, C. L. Chiu, K. Y. Tsai, P. K. Chen, P. C. Peng, and H. L. Wang, "Inspecting the current thickness of a refractory wall inside an operational blast furnace using the impact echo method," NDT E Int. 66, 43-51 (2014).
J. Sebastian, "Monitoring of refractory wall recession using high-temperature Impact-echo instrumentation," University of Dayton, Tech. Rep., 2004.
W. L. Ying, R. MacRosty, P. Gebski, R. Pula, A. Sadri, and T. Gerritsen, "Managing furnace integrity by utilizing non-destructive testing (NDT) and monitoring techniques," Conference of Metallurgists, paper no. 8709 (2015).
M. Sansalone and W. B. Streett, Impact-Echo: Nondestructive Evaluation of Concrete and Masonry (Bullbrier Press, New York, 1997), pp. 256-257.
F. Schubert, H. Wiggenhauser, and R. Lausch, "On the accuracy of thickness measurements in impact-echo testing of finite concrete specimens-numerical and experimental results," Ultrasonics 42, 897-901 (2004).
M. T. Ghomi, J. Mahmoudi, and M. Darabi, "Concrete plate thickness measurement using the indirect impactecho method," NDT E Int. 28, 119-144 (2013).
J. S. Popovics, G. P. Centrangolo, and N. D. Jackson, "Experimental investigation of impact-echo method for concrete slab thickness measurement," J. Korean Soc. Nondestruct. Test. 26, 427-439 (2006).
M. T. A. Chaudhary, "Effectiveness of impact echo testing in detecting flaws in prestressed concrete slabs," Construction and Building Materials 47, 753-759 (2013).
H. Azari, S. Nazarian, and D. Yuan, "Assessing sensitivity of impact echo and ultrasonic surface waves methods for nondestructive evaluation of concrete structures," Construction and Building Materials 71, 384-391 (2014).
Y. S. Cho, S. U. Hong, and M. S. Lee, "The assessment of the compressive strength and thickness of concrete structures using nondestructive testing and an artificial neural network," NDT E Int. 24, 277-288 (2009).
D. G. Aggelis, T. Shiotani, and K. Kasai, "Evaluation of grouting in tunnel lining using impact-echo," Tunnelling and Underground Space Technology 23, 629-637 (2008).
J. S. Popovics, N. Ryden, A. Gibson, S. Alzate, I. L. Al-Qadi, and W. Xie, "New developments in NDE methods for pavements" AIP Conf. Proc. 1320-1327 (2008).
K. R. Maser, T. J. Holland, R. Roberts, and J. Popovics, "NDE methods for quality assurance of new pavement thickness," Int. J. Pavement Eng. 7, 1-10 (2006).
S. K. U. Rehman, Z. Ibrahim, S. A. Memon, and M. Jameel, "Nondestructive test methods for concrete bridges: A review," Construction and Building Materials 107, 58-86 (2016).
A. N. Pyrikove, A. V. Likhodievskii, V. N. Loginov, A. E. Paren'kov, and O. V. Golubev, "Prospects for refractory blast-furnace linings," Steel in Translation 38, 132-140 (2008).
N. J. Carino, "Impact-echo method: An overview," Proc. Structure Congress & Exposition, 118 (2001).
M. T. Hu, Y. Lin, and C. C. Cheng, "Method for determining internal p-wave speed and thickness of concrete plates," ACI Materials J. 103, 327-335 (2006).
C. Hsiao, C. C. Cheng, T. Liou, and Y. Juang, "Detecting flaws in concrete blocks using the impact-echo method," NDT E Int. 41, 98-107 (2008).
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