Cracking of GSO Single Crystal Induced by Thermal Stress
N. Miyazaki, T. Tamura, K. Yamamoto

Source CMES: Computer Modeling in Engineering & Sciences, Vol. 1, No. 1, pp. 99-106, 2000
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Keywords finite element method, thermal stress, cracking, single crystal, crystal anisotropy
Abstract Quantitative estimation of the failure of a gadolinium orthosilicate (Gd$_2$SiO$_5$, hereafter abbreviated as GSO) single crystal induced by thermal stress was investigated. A GSO cylindrical test specimen was heated in a silicone oil bath, then subjected to large thermal stress by room temperature silicone oil. Cracking occurred during cooling. The transient heat conduction analysis was performed to obtain temperature distribution in the test specimen at the time of cracking, using the surface temperatures measured in the test. Then the thermal stress was calculated using the temperature profile of the test specimen obtained from the heat conduction analysis. It is found from the results of the thermal stress analysis and the observation of the cracking in the test specimens that the cracking induced by thermal stress occurs in a cleavage plane due to the stress component normal to the plane. Three-point bending tests were also performed to examine the relation between the critical stress for the cracking induced by thermal stress and the three-point bending strength obtained from small-sized test specimens. Both sets of failure data obey the Weibull distribution, and the Weibull distribution of the critical stress for the cracking induced by thermal stress can be very well estimated from that of the three-point bending strength by correcting size effect using the Weibull distribution's weakest link model.
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