ASTM C1279-00e1
(Test Method)Standard Test Method for Non-Destructive Photoelastic Measurement of Edge and Surface Stresses in Annealed, Heat-Strengthened, and Fully Tempered Flat Glass
Standard Test Method for Non-Destructive Photoelastic Measurement of Edge and Surface Stresses in Annealed, Heat-Strengthened, and Fully Tempered Flat Glass
SCOPE
1.1 This test method covers the determination of edge stresses and surface stresses in annealed, heat-strengthened, and fully tempered flat glass products.
1.2 This test method is non-destructive.
1.3 This test method uses transmitted light and is, therefore, applicable to light-transmitting glasses.
1.4 The test method is not applicable to chemically-tempered glass.
1.5 Using the procedure described, surface stresses can be measured only on the "tin" side of float glass.
1.6 Surface-stress measuring instruments are designed for a specific range of surface index of refraction.
1.7 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:C1279–00
Standard Test Method for
Non-Destructive Photoelastic Measurement of Edge and
Surface Stresses in Annealed, Heat-Strengthened, and Fully
1
Tempered Flat Glass
This standard is issued under the fixed designation C 1279; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1
e NOTE—Equation 11 was editorially revised in October 2001.
1. Scope 3. Terminology
1.1 This test method covers the determination of edge 3.1 Definitions:
stresses and surface stresses in annealed, heat-strengthened, 3.1.1 analyzer—a polarizing element, typically positioned
and fully tempered flat glass products. between the specimen being evaluated and the viewer.
1.2 This test method is non-destructive. 3.1.2 polarizer—an optical assembly that transmits light
1.3 This test method uses transmitted light and is, therefore, vibrating in a single planar direction, typically positioned
applicable to light-transmitting glasses. between a light source and the specimen being evaluated.
1.4 The test method is not applicable to chemically- 3.1.3 retardation compensator—an optical device, variants
tempered glass. of which are used to quantify the optical retardation produced
1.5 Using the procedure described, surface stresses can be in transparent birefringent materials: typically positioned be-
measured only on the “tin” side of float glass. tween the specimen being evaluated and the analyzer.
1.6 Surface-stress measuring instruments are designed for a 3.2 For definition of terms used in this test method, refer to
specific range of surface index of refraction. Terminology C 162.
1.7 This standard does not purport to address all of the
4. Summary of Test Methods
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- 4.1 Two test methods are described in this standard:
priate safety and health practices and determine the applica- 4.1.1 Procedure A describes a test method for measuring
surface stress using light propagating nearly parallel to the
bility of regulatory limitations prior to use.
surface.
2. Referenced Documents
4.1.2 Procedure B describes a test method for measuring
2.1 ASTM Standards: edge-stress using light propagating in the direction perpendicu-
2
C 162 Terminology of Glass and Glass Products lar to the surface.
C 770 Test Method for Measurements of Glass Stress- 4.2 In both methods, the fundamental photoelastic concept
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Optical Coefficient is used. As a result of stresses, the material becomes optically
C 1048 Specification for Heat-Treated Glass: Kind HS, anisotropic or birefringent. When polarized light propagates
2
Kind FT Coated and Uncoated Glass through such anisotropic materials, the differences in the speed
F 218 Test Method for Analyzing Stress in Glass of light rays vibrating along the maximum and minimum
2.2 Other Documents: principal stress introduce a relative retardation between these
3
Engineering Standards Manual rays. This relative retardation is proportional to the measured
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“Surface and Edge Stress in Tempered Glass” stresses,andcanbeaccuratelydeterminedusingcompensators.
For additional background see “Surface and Edge Stress in
4
Tempered Glass” .
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This test method is under the jurisdiction of ASTM Committee C14 on Glass
and Glass Products and is the direct responsibility of Subcommittee C14.08 on Flat
5. Significance and Use
Glass.
5.1 The strength and performance of heat-strengthened and
Current edition approved Dec. 10, 2000. Published February 2001.
Orginally published as C 1279-94. Last previous edition C 1070-94.
fully-tempered glass is greatly affected by the surface and edge
2
Annual Book of ASTM Standards, Vol 15.02.
stress induced during the heat-treating process.
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Available from GANA, 3310 Harrison, Topeka, Kansas.
4
Redner, A. S. and Voloshin, A. S., Proceedings of the Ninth International
Conference on Experimental Mechanics, Denmark, 1990.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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C1279–00
R 5 b·y (3)
5.2 The edge and surface stress levels are specified in
c
3
Specification C 1048, in the Engineering Standards Manual of
Where bisaconstant,determinedbythemanufacturerofthe
GTA and in foreign specifications.
compensator. The observer sees in the compensator plane a
5.3 This test method offers a direct and convenient way to
total retardation R.
non-destructively determine the residual state of stress on the
R 5 R 1 R 5 a·C·S·x 1 b·y (4)
s c
surface and at the edge of annealed a
...
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