2000 Fiscal Year Final Research Report Summary
Study on the method of thermal stress cleaving of a brittle solid
| Project/Area Number |
11650094
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Materials/Mechanics of materials
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| Research Institution | Nagasaki University |
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Principal Investigator |
IMAI Yasufumi Nagasaki University, Faculty of Engineering, Professor, 工学部, 教授 (50039682)
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| Co-Investigator(Kenkyū-buntansha) |
MOTOMURA Fumitaka Nagasaki University, Faculty of Engineering, Research Assistant, 工学部, 助手 (40274625)
SAIMOTO Akihide Nagasaki University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (00253633)
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| Project Period (FY) |
1999 – 2000
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| Keywords | Unsteady thermal stress / Thermal stress cleaving / Band heating / Finite element method / Stress intensity factor |
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| Research Abstract |
Unsteady thermal stress fields in a rectangular parallelepiped and a cylinder was analyzed by a finite element method to get an effective heating method in the thermal stress cleaving of a 3-dimensional block.
1 Band heating on a surface is more effective than point heating or circular areal heating for the initiation of a crack at the non-heated part located at the extension of the heating band.
2 For a rectangular parallelepiped, tensile thermal stresses appear perpendicular to the longitudinal direction of the band almost independently to the width of band. A high tensile stress occurs near the end face.
3 For the same heating time, the narrower band heating gives the higher stress near the surface but in the inner region, the broader band gives the higher stress. The heating width, 0.05〜0.1 of the block width achieves almost uniform tensile thermal stress distribution throughout the thickness.
4 Simultaneous heating on both upper and lower surfaces is more effective than one side.
5 When a through-thickness crack extends to the middle from the end face, the mode I stress intensity factor becomes negative near the upper and lower surface of the block. This explains why the crack growth near the surface retards compared with at the middle part of the thickness.
6 For the thermal stress cleaving of a cylinder, band heating of partial circumference produces an axial normal stress at the non-heated part of the outer surface.
7 When the radius to height ratio exceeds 2, non-heated angel, 15〜20 degree and heating width, 0.2〜0.3 of the radius are appropriate for the production of sufficient thermal stress to initiate a crack on a glass cylinder.
8 A block whose geometry is near to a sphere is hard to be cleaved by a thermal stress.
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