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1. Forward Modelling and Detection of GPR in Urban Road Base Disease

Author

Y.W. Bao, R.X. Gao, D. Guo, S.S. Bai, and X.J. Xin

Subjects
Chemical engineering, TP155-156, Computer engineering. Computer hardware, TK7885-7895
Abstract

Ground penetrating radar is a high-resolution engineering geophysical method which has better detection effect to disengaging, cavities and leakiness in urban road base. This paper is based on the principle of ray tracing through the forward modelling of urban road base hollow, empty and not dense disease, analyses waveform, frequency, wave propagation characteristics of primary disease forward image simulation. The paper summarizes the urban road base diseases in ground penetrating radar profile feature of signal, and analyses field exploration radar profile and further research on primary diseases of urban road ground penetrating radar fingerprint for urban road base disease detection of ground penetrating radar data interpretation to provide the reference.

Published
2015
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2. Design and Testing of the Front-End Electronics of WCDA in LHAASO

Author

F. Aharonian, Q. An, null Axikegu, L.X. Bai, Y.X. Bai, Y.W. Bao, D. Bastieri, X.J. Bi, Y.J. Bi, H. Cai, J.T. Cai, Z. Cao, J. Chang, J.F. Chang, X.C. Chang, B.M. Chen, J. Chen, L. Chen, M.J. Chen, M.L. Chen, Q.H. Chen, S.H. Chen, S.Z. Chen, T.L. Chen, X.L. Chen, Y. Chen, N. Cheng, Y.D. Cheng, S.W. Cui, X.H. Cui, Y.D. Cui, B.Z. Dai, H.L. Dai, Z.G. Dai, null Danzengluobu, R.S. Dong, X.J. Dong, J.H. Fan, Y.Z. Fan, Z.X. Fan, J. Fang, K. Fang, C.F. Feng, L. Feng, S.H. Feng, Y.L. Feng, B. Gao, C.D. Gao, Q. Gao, W. Gao, M.M. Ge, L.S. Geng, G.H. Gong, Q.B. Gou, J.L. Gu, M.H. Gu, J.G. Guo, X.L. Guo, Y.Q. Guo, Y.Y. Guo, Y.A. Han, H.H. He, H.N. He, J.C. He, S.L. He, X.B. He, Y. He, Z.Q. He, M. Heller, Y.K. Hor, C. Hou, X. Hou, H.B. Hu, S. Hu, S.C. Hu, X.J. Hu, D.H. Huang, Q.L. Huang, W.H. Huang, X.T. Huang, Z.C. Huang, F. Ji, X.L. Ji, H.Y. Jia, K. Jiang, Z.J. Jiang, C. Jin, D. Kuleshov, K. Levochkin, B.B. Li, C. Li, F. Li, H.B. Li, H.C. Li, H.Y. Li, J. Li, K. Li, W.L. Li, X. Li, X.R. Li, Y. Li, Y.Z. Li, Z. Li, E.W. Liang, Y.F. Liang, S.J. Lin, B. Liu, C. Liu, D. Liu, H. Liu, H.D. Liu, J. Liu, J.L. Liu, J.S. Liu, J.Y. Liu, M.Y. Liu, R.Y. Liu, S.M. Liu, W. Liu, Y.N. Liu, Z.X. Liu, W.J. Long, R. Lu, H.K. Lv, B.Q. Ma, L.L. Ma, X.H. Ma, J.R. Mao, A. Masood, W. Mitthumsiri, T. Montaruli, Y.C. Nan, B.Y. Pang, P. Pattarakijwanich, Z.Y. Pei, B.D. Piazzoli, M.Y. Qi, J.J. Qin, D. Ruffolo, V. Rulev, A. Saiz, L. Shao, O. Shchegolev, X.D. Sheng, J.R. Shi, C.X. Song, H.C. Song, Yu. V. Stenkin, V. Stepanov, Q.N. Sun, X.N. Sun, Z.B. Sun, P.H.T. Tam, Z.B. Tang, W.W. Tian, D. della Volpe, B.D. Wang, C. Wang, H. Wang, H.G. Wang, J.C. Wang, J.S. Wang, L.P. Wang, L.Y. Wang, R.N. Wang, W. Wang, X.G. Wang, X.J. Wang, X.Y. Wang, Y.D. Wang, Y.J. Wang, Y.P. Wang, Z. Wang, Z.H. Wang, Z.X. Wang, D.M. Wei, J.J. Wei, Y.J. Wei, T. Wen, C.Y. Wu, H.R. Wu, S. Wu, W.X. Wu, X.F. Wu, S.Q. Xi, J. Xia, J.J. Xia, G.M. Xiang, G. Xiao, H.B. Xiao, G.G. Xin, Y.L. Xin, Y. Xing, D.L. Xu, R.X. Xu, L. Xue, D.H. Yan, X.B. Yan, C.W. Yang, F.F. Yang, J.Y. Yang, L.L. Yang, M.J. Yang, R.Z. Yang, S.B. Yang, Y.H. Yao, Z.G. Yao, Y.M. Ye, L.Q. Yin, N. Yin, X.H. You, Z.Y. You, Y.H. Yu, Q. Yuan, H.D. Zeng, T.X. Zeng, W. Zeng, Z.K. Zeng, M. Zha, X.X. Zhai, B.B. Zhang, H.M. Zhang, H.Y. Zhang, J.L. Zhang, J.W. Zhang, L. Zhang, L.X. Zhang, P.F. Zhang, P.P. Zhang, R. Zhang, S.R. Zhang, S.S. Zhang, X. Zhang, X.P. Zhang, Y. Zhang, Y.F. Zhang, Y.L. Zhang, B. Zhao, J. Zhao, L. Zhao, L.Z. Zhao, S.P. Zhao, F. Zheng, Y. Zheng, B. Zhou, H. Zhou, J.N. Zhou, P. Zhou, R. Zhou, S.Z. Zhou, X.X. Zhou, C.G. Zhu, F.R. Zhu, H. Zhu, K.J. Zhu, and X. Zuo

Subjects
Nuclear and High Energy Physics, Photomultiplier, Dynamic range, Cherenkov detector, Detector, law.invention, Root mean square, Air shower, Nuclear Energy and Engineering, Observatory, law, Environmental science, Electronics, Electrical and Electronic Engineering, Remote sensing
Abstract

Water Cherenkov detector array (WCDA) is one of the key parts of the Large High Altitude Air Shower Observatory (LHAASO), the construction of which was completed by the end of 2020. The WCDA covers a 78 000-m2 area and there exist 3120 large size photomultiplier tubes (PMTs) in three ponds: 8-in PMTs are used in WCDA pond No. 1 and 20-in PMTs are used in ponds No. 2 and No. 3. The front-end electronics (FEE) system based on multigain measurement technique is designed to achieve both high-precision time and charge measurements over a large dynamic range from single photon electron (S.P.E.) to 4000 P.E. (for water pond No. 1)/1800 P.E. (for water ponds No. 2 and No. 3). To achieve a high-quality clock distribution and phase alignment as well as mixed transmission of data, clock, and commands in one fiber over a long distance, an enhanced white rabbit (WR) technique is used. Testing of all the 350 FEE modules for the WCDA is presented in this article. Test results indicate that the charge resolution is better than 20% at S.P.E. and 1% at 1800/4000 P.E. and the time resolution is better than 300 ps root mean square (rms), which successfully meets the application requirement. All the FEE modules have been fabricated and installed for the LHAASO WCDA from 2018 to 2020, and the initial commissioning operation indicates that the FEEs function well.

Published
2021
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3. Corrigendum to 'Performance test of the electromagnetic particle detectors for the LHAASO experiment' [Nucl. Instrum. Methods Phys. Res. A 1001 (2021) 165193]

Author

F. Aharonian, Q. An, null Axikegu, L.X. Bai, Y.X. Bai, Y.W. Bao, D. Bastieri, X.J. Bi, Y.J. Bi, H. Cai, J.T. Cai, Z. Cao, J. Chang, J.F. Chang, X.C. Chang, B.M. Chen, J. Chen, L. Chen, M.J. Chen, M.L. Chen, Q.H. Chen, S.H. Chen, S.Z. Chen, T.L. Chen, X.L. Chen, Y. Chen, N. Cheng, Y.D. Cheng, S.W. Cui, X.H. Cui, Y.D. Cui, B.Z. Dai, H.L. Dai, Z.G. Dai, null Danzengluobu, D. della Volpe, B. D’Ettorre Piazzoli, X.J. Dong, J.H. Fan, Y.Z. Fan, Z.X. Fan, J. Fang, K. Fang, C.F. Feng, L. Feng, S.H. Feng, Y.L. Feng, B. Gao, C.D. Gao, Q. Gao, W. Gao, M.M. Ge, L.S. Geng, G.H. Gong, Q.B. Gou, M.H. Gu, J.G. Guo, X.L. Guo, Y.Q. Guo, Y.Y. Guo, Y.A. Han, H.H. He, H.N. He, J.C. He, S.L. He, X.B. He, Y. He, M. Heller, Y.K. Hor, C. Hou, X. Hou, H.B. Hu, S. Hu, S.C. Hu, X.J. Hu, D.H. Huang, Q.L. Huang, W.H. Huang, X.T. Huang, Z.C. Huang, F. Ji, X.L. Ji, H.Y. Jia, K. Jia, K. Jiang, Z.J. Jiang, C. Jin, D. Kuleshov, K. Levochkin, B. Li, B.B. Li, C. Li, F. Li, H. Li, H.B. Li, H.C. Li, H.Y. Li, J. Li, K. Li, W.L. Li, X. Li, X.R. Li, Y. Li, Y.Z. Li, Z. Li, E.W. Liang, Y.F. Liang, S.J. Lin, B. Liu, C. Liu, D. Liu, H. Liu, H.D. Liu, J. Liu, J.L. Liu, J.S. Liu, J.Y. Liu, M.Y. Liu, R.Y. Liu, S.M. Liu, W. Liu, Y.N. Liu, Z.X. Liu, W.J. Long, R. Lu, H.K. Lv, B.Q. Ma, L.L. Ma, X.H. Ma, J.R. Mao, A. Masood, W. Mitthumsiri, T. Montaruli, Y.C. Nan, B.Y. Pang, P. Pattarakijwanich, Z.Y. Pei, M.Y. Qi, D. Ruffolo, V. Rulev, A. Sáiz, L. Shao, O. Shchegolev, X.D. Sheng, J.R. Shi, H.C. Song, Yu.V. Stenkin, V. Stepanov, Q.N. Sun, X.N. Sun, Z.B. Sun, P.H. T. Tam, Z.B. Tang, W.W. Tian, B.D. Wang, C. Wang, H. Wang, H.G. Wang, J.C. Wang, J.S. Wang, L.P. Wang, L.Y. Wang, R.N. Wang, W. Wang, X.G. Wang, X.J. Wang, X.Y. Wang, Y.D. Wang, Y.J. Wang, Y.P. Wang, Z. Wang, Z.H. Wang, Z.X. Wang, D.M. Wei, J.J. Wei, Y.J. Wei, T. Wen, C.Y. Wu, H.R. Wu, S. Wu, W.X. Wu, X.F. Wu, S.Q. Xi, J. Xia, J.J. Xia, G.M. Xiang, G. Xiao, H.B. Xiao, G.G. Xin, Y.L. Xin, Y. Xing, D.L. Xu, R.X. Xu, L. Xue, D.H. Yan, C.W. Yang, F.F. Yang, J.Y. Yang, L.L. Yang, M.J. Yang, R.Z. Yang, S.B. Yang, Y.H. Yao, Z.G. Yao, Y.M. Ye, L.Q. Yin, N. Yin, X.H. You, Z.Y. You, Y.H. Yu, Q. Yuan, H.D. Zeng, T.X. Zeng, W. Zeng, Z.K. Zeng, M. Zha, X.X. Zhai, B.B. Zhang, H.M. Zhang, H.Y. Zhang, J.L. Zhang, J.W. Zhang, L. Zhang, L.X. Zhang, P.F. Zhang, P.P. Zhang, R. Zhang, S.R. Zhang, S.S. Zhang, X. Zhang, X.P. Zhang, Y. Zhang, Y.F. Zhang, Y.L. Zhang, B. Zhao, J. Zhao, L. Zhao, L.Z. Zhao, S.P. Zhao, X. Zhao, F. Zheng, Y. Zheng, B. Zhou, H. Zhou, J.N. Zhou, P. Zhou, R. Zhou, X.X. Zhou, C.G. Zhu, F.R. Zhu, H. Zhu, K.J. Zhu, and X. Zuo

Subjects
Physics, Nuclear physics, Nuclear and High Energy Physics, Detector, Particle, Instrumentation
Published
2022
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4. Performance of LHAASO-WCDA and observation of the Crab Nebula as a standard candle *

Author

F. Aharonian, Q. An, 克古 Axikegu, L.X. Bai, Y.X. Bai, Y.W. Bao, D. Bastieri, X.J. Bi, Y.J. Bi, H. Cai, J.T. Cai, Z. Cao, J. Chang, J.F. Chang, X.C. Chang, B.M. Chen, J. Chen, L. Chen, M.J. Chen, M.L. Chen, Q.H. Chen, S.H. Chen, S.Z. Chen, T.L. Chen, X.L. Chen, Y. Chen, N. Cheng, Y.D. Cheng, S.W. Cui, X.H. Cui, Y.D. Cui, B.Z. Dai, H.L. Dai, Z.G. Dai, 罗布 Danzengluobu, D. della Volpe, B. D'Ettorre Piazzoli, X.J. Dong, J.H. Fan, Y.Z. Fan, Z.X. Fan, J. Fang, K. Fang, C.F. Feng, L. Feng, S.H. Feng, Y.L. Feng, B. Gao, C.D. Gao, Q. Gao, W. Gao, M.M. Ge, L.S. Geng, G.H. Gong, Q.B. Gou, M.H. Gu, J.G. Guo, X.L. Guo, Y.Q. Guo, Y.Y. Guo, Y.A. Han, H.H. He, H.N. He, J.C. He, S.L. He, X.B. He, Y. He, M. Heller, Y.K. Hor, C. Hou, X. Hou, H.B. Hu, S. Hu, S.C. Hu, X.J. Hu, D.H. Huang, Q.L. Huang, W.H. Huang, X.T. Huang, Z.C. Huang, F. Ji, X.L. Ji, H.Y. Jia, K. Jiang, Z.J. Jiang, C. Jin, D. Kuleshov, K. Levochkin, B.B. Li, C. Li, F. Li, H.B. Li, H.C. Li, H.Y. Li, J. Li, K. Li, W.L. Li, X. Li, X.R. Li, Y. Li, Y.Z. Li, Z. Li, E.W. Liang, Y.F. Liang, S.J. Lin, B. Liu, C. Liu, D. Liu, H. Liu, H.D. Liu, J. Liu, J.L. Liu, J.S. Liu, J.Y. Liu, M.Y. Liu, R.Y. Liu, S.M. Liu, W. Liu, Y.N. Liu, Z.X. Liu, W.J. Long, R. Lu, H.K. Lv, B.Q. Ma, L.L. Ma, X.H. Ma, J.R. Mao, A. Masood, W. Mitthumsiri, T. Montaruli, Y.C. Nan, B.Y. Pang, P. Pattarakijwanich, Z.Y. Pei, M.Y. Qi, B.Q. Qiao, D. Ruffolo, V. Rulev, A. Sáiz, L. Shao, O. Shchegolev, X.D. Sheng, J.R. Shi, H.C. Song, Yu.V. Stenkin, V. Stepanov, Q.N. Sun, X.N. Sun, Z.B. Sun, P.H.T. Tam, Z.B. Tang, W.W. Tian, B.D. Wang, C. Wang, H. Wang, H.G. Wang, J.C. Wang, J.S. Wang, L.P. Wang, L.Y. Wang, R.N. Wang, W. Wang, X.G. Wang, X.J. Wang, X.Y. Wang, Y.D. Wang, Y.J. Wang, Y.P. Wang, Z. Wang, Z.H. Wang, Z.X. Wang, D.M. Wei, J.J. Wei, Y.J. Wei, T. Wen, C.Y. Wu, H.R. Wu, S. Wu, W.X. Wu, X.F. Wu, S.Q. Xi, J. Xia, J.J. Xia, G.M. Xiang, G. Xiao, H.B. Xiao, G.G. Xin, Y.L. Xin, Y. Xing, D.L. Xu, R.X. Xu, L. Xue, D.H. Yan, C.W. Yang, F.F. Yang, J.Y. Yang, L.L. Yang, M.J. Yang, R.Z. Yang, S.B. Yang, Y.H. Yao, Z.G. Yao, Y.M. Ye, L.Q. Yin, N. Yin, X.H. You, Z.Y. You, Y.H. Yu, Q. Yuan, H.D. Zeng, T.X. Zeng, W. Zeng, Z.K. Zeng, M. Zha, X.X. Zhai, B.B. Zhang, H.M. Zhang, H.Y. Zhang, J.L. Zhang, J.W. Zhang, L. Zhang, L.X. Zhang, P.F. Zhang, P.P. Zhang, R. Zhang, S.R. Zhang, S.S. Zhang, X. Zhang, X.P. Zhang, Y. Zhang, Y.F. Zhang, Y.L. Zhang, B. Zhao, J. Zhao, L. Zhao, L.Z. Zhao, S.P. Zhao, F. Zheng, Y. Zheng, B. Zhou, H. Zhou, J.N. Zhou, P. Zhou, R. Zhou, X.X. Zhou, C.G. Zhu, F.R. Zhu, H. Zhu, K.J. Zhu, X. Zuo, and (The LHAASO Collaboration)

Subjects
Physics, Nuclear and High Energy Physics, 010308 nuclear & particles physics, Cherenkov detector, Point source, Astrophysics::High Energy Astrophysical Phenomena, Cosmic distance ladder, Gamma ray, Astronomy and Astrophysics, Cosmic ray, Astrophysics, 01 natural sciences, law.invention, Crab Nebula, law, 0103 physical sciences, Spectral energy distribution, Angular resolution, 010306 general physics, Instrumentation
Abstract

The first Water Cherenkov detector of the LHAASO experiment (WCDA-1) has been operating since April 2019. The data for the first year have been analyzed to test its performance by observing the Crab Nebula as a standard candle. The WCDA-1 achieves a sensitivity of 65 mCU per year, with a statistical threshold of 5 . To accomplish this, a 97.7% cosmic-ray background rejection rate around 1 TeV and 99.8% around 6 TeV with an approximate photon acceptance of 50% is achieved after applying an algorithm to separate gamma-induced showers. The angular resolution is measured using the Crab Nebula as a point source to be approximately 0.45° at 1 TeV and better than 0.2° above 6 TeV, with a pointing accuracy better than 0.05°. These values all match the design specifications. The energy resolution is found to be 33% for gamma rays around 6 TeV. The spectral energy distribution of the Crab Nebula in the range from 500 GeV to 15.8 TeV is measured and found to be in agreement with the results from other TeV gamma ray observatories.

Published
2021
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5. A novel method to evaluate Young׳s modulus of ceramics at high temperature up to 2100°C

Author

C.G. Wei, Y.W. Bao, Yuan Tian, Z. Liu, D.T. Wan, and Chun Lin Hu

Subjects
Work (thermodynamics), Materials science, Process Chemistry and Technology, Composite number, Modulus, Young's modulus, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, symbols.namesake, Creep, visual_art, Materials Chemistry, Ceramics and Composites, visual_art.visual_art_medium, symbols, Ceramic, Graphite, Composite material, Deformation (engineering)
Abstract

Although it is important to understand Young׳s modulus and creep behavior of ceramics at ultra-high temperature from 1500 °C to 2300 °C, measuring these properties accurately at high temperature above 1600 °C is not very easy due to the difficulty of the deformation measurement or invalid testing instruments at such high temperature. This work presented a solution to this problem via a combination of the split ring test and relative method (viz. relative split ring method). The real deformation of the split ring at ultra-high temperature could be easily determined from the difference of cross-beam displacements between the split ring and a rigid disk under the same loads. Experiments of graphite and C/SiC/ZrB 2 composite at ultra-high temperature demonstrated the validity and convenience of the relative split ring method, which would provide a simple and efficient approach to evaluate Young׳s modulus of ceramic materials at ultra-high temperature.

Published
2015
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6. Mechanical properties of Y2Ti2O7

Author

Takayuki Komatsu, Jun Shirahata, Y.W. Bao, Hisayuki Suematsu, Koichi Niihara, Lingfeng He, Ikuo Ihara, Tsuneo Suzuki, and Tadachika Nakayama

Subjects
Materials science, Mechanical Engineering, Metals and Alloys, Modulus, Nanoindentation, Condensed Matter Physics, Crystallography, Fracture toughness, Flexural strength, Mechanics of Materials, Indentation, visual_art, visual_art.visual_art_medium, General Materials Science, Ceramic, Composite material
Abstract

The mechanical properties of Y2Ti2O7 ceramics have been systematically characterized. Y2Ti2O7 shows higher hardness (12.1 GPa) than Y2O3 and TiO2. The Young’s modulus of Y2Ti2O7 (262 GPa) is close to that of TiO2 and 50% higher than that of Y2O3. The fracture toughness (1.9 MPa m1/2) and bending strength (206 MPa) are comparable with those of Y2O3 but half those of TiO2. The indentation size effect on the hardness in nanoindentation tests is discussed based on the Nix–Gao model.

Published
2011
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7. Elastic and thermal properties of [Zr.sub.2][Al.sub.3][C.sub.4]: experimental investigations and ab initio calculations

Author

L.F. He, J.Y. Wang, and Y.W. Bao

Subjects
Carbides -- Thermal properties, Zirconium -- Thermal properties, Zirconium -- Analysis, Heat -- Conduction, Heat -- Analysis, Physics
Abstract

Theoretical and experimental approaches are used for studying the elastic and thermal properties of [Zr.sub.2][Al.sub.3][C.sub.4] carbide. The elastic and thermal properties are useful for understanding the intrinsic properties of [Zr.sub.2][Al.sub.3][C.sub.4] for high temperature applications.

Published
2007

8. Local strength evaluation and proof test of glass components via spherical indentation

Author

Y.W. Bao and S.J. Gao

Subjects
Materials science, Critical load, Test method, Condensed Matter Physics, Electronic, Optical and Magnetic Materials, Contact mechanics, Acoustic emission, Indentation, visual_art, Materials Chemistry, Ceramics and Composites, visual_art.visual_art_medium, Ceramic, Proof test, Composite material, Reliability (statistics)
Abstract

Hertzian contact crack formation combined with acoustic emission was used to evaluate the local strength of glass in situ. The relationship between the critical load and the strength of the glass sample was established. Based on this model, a strength proof test was designed to examine the reliability of glass components in service. Moreover, a new testing device was designed and made for accomplishing this test. It has been demonstrated that this simple testing method is convenient and available for measuring or estimating the surface strength of a glass component in service, without using a standard specimen and a rupture test in laboratory.

Published
2008
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9. Investigation in biaxial-stress effect on mode I fracture resistance of brittle materials by FEM simulation and K–G–J–δ relationship

Author

Y. Qiu, Y.W. Bao, and Wei Hong Li

Subjects
Strain energy release rate, Materials science, Mechanical Engineering, Biaxial tensile test, Fracture mechanics, Condensed Matter Physics, Brittleness, Fracture toughness, Mechanics of Materials, Forensic engineering, Fracture (geology), General Materials Science, Composite material, Stress intensity factor, Stress concentration
Abstract

Difference in the stress distribution and failure initiation for brittle materials between uniaxial and biaxial loads was confirmed by FEM simulation. To explain the influence of biaxial stress on fracture, the relationship among the stress intensity factor K, the energy release rate G, the crack opening displacement and J-integral is investigated. It is demonstrated that the crack opening displacement and the strain energy release rate are biaxiality-dependent because they are related to strain that is affected by biaxial stress, whereas K and J are biaxiality-independent. Thus, the conventional concept on the equivalent relation among the four parameters is found to be invalid for brittle materials under biaxial stress, and the influence of biaxial stress on fracture resistance is attributed to the strain-depending failure.

Published
2005
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10. Evaluating high-temperature modulus and elastic recovery of Ti3SiC2 and Ti3AlC2 ceramics

Author

Y.W Bao and Yanchun Zhou

Subjects
Bulk modulus, Materials science, Mechanical Engineering, Modulus, Young's modulus, Bending, Atmospheric temperature range, Condensed Matter Physics, symbols.namesake, Time–temperature superposition, Mechanics of Materials, symbols, General Materials Science, Elasticity (economics), Composite material, Elastic modulus
Abstract

Elastic modulus and elastic recovery of both Ti3SiC2 and Ti3AlC2 at various temperatures were evaluated using cyclic loading–unloading in three-point bending tests and comparing relative slopes. It was found that the elastic moduli of Ti3SiC2 and Ti3AlC2, 310 and 288 GPa, were nearly constants in the temperature range from 20 to 1000 °C and then dramatically declined with further increasing of temperature. Elastic recovery as a function of temperature exhibited quite similar curve as the elastic modulus. The simple testing method was demonstrated convenient for estimating the elastic modulus and plastic deformation of ceramics at high temperature.

Published
2003
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11. Nondestructively determining local strength and residual stress of glass by Hertzian indentation

Author

J.J Yang, Jianghong Gong, L Sun, Y.W Bao, and S.B Su

Subjects
Materials science, Polymers and Plastics, Metals and Alloys, Electronic, Optical and Magnetic Materials, Stress (mechanics), Residual stress, Indentation, Contact position, Crack initiation, Ultimate tensile strength, Ceramics and Composites, SPHERES, Composite material, Material properties
Abstract

Hertzian indentation was used to evaluate the local strength of glasses and to estimate residual stresses in strengthened glasses. It was found that initiation of Hertzian crack in glasses depends on the mean stress within a surface thickness related to material properties, but independent of the peak stress. The maximum mean stress for crack initiation was a constant and was defined as the local strength of the specimen at the contact position. Indentation experiments, using alumina spheres with various sizes as indenters, were performed on unstrengthened and strengthened glasses, respectively. The results showed a good stability in the local strength and a good agreement between the residual stresses measured by the present method and by a polarizing device. In addition, the potential merits of this method are: a) Nondestructive and in-situ measurement of strength can be performed without using a standard specimen and a rupture test; b) Strength proof test and strength comparison can be easily preformed.

Published
2002
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