ASTM C158-02

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Designation:C158–02
Standard Test Methods for
Strength of Glass by Flexure (Determination of Modulus of
1
Rupture)
This standard is issued under the fixed designation C158; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope E380 Practice for Use of the International System of Units
4
(SI) (the Modernized Metric System)
1.1 These test methods cover the determination of the
modulus of rupture in bending of glass and glass-ceramics.
3. Terminology
1.2 These test methods are applicable to annealed and
3.1 Definitions:
prestressed glasses and glass-ceramics available in varied
3.1.1 glass-ceramics—solid materials, predominantly crys-
forms.Alternative test methods are described; the test method
talline in nature, formed by the controlled crystallization of
used shall be determined by the purpose of the test and
glasses.
geometric characteristics of specimens representative of the
3.1.2 modulus of rupture in bending—the value of maxi-
material.
mum tensile or compressive stress (whichever causes failure)
1.2.1 Test Method A is a test for modulus of rupture of flat
in the extreme fiber of a beam loaded to failure in bending
glass.
computed from the flexure formula:
1.2.2 Test Method B is a comparative test for modulus of
Mc
rupture of glass and glass-ceramics.
S 5 (1)
b
I
1.3 The test methods appear in the following order:
Sections
where:
Test Method A 6 to 9
M = maximum bending moment, computed from the
Test Method B 10 to 15
maximum load and the original moment arm,
1.4 This standard does not purport to address all of the
c = initial distance from the neutral axis to the extreme
safety concerns, if any, associated with its use. It is the
fiber where failure occurs, and
responsibility of the user of this standard to establish appro-
I = initialmomentofinertiaofthecrosssectionaboutthe
priate safety and health practices and determine the applica-
neutral axis.
bility of regulatory limitations prior to use. Specific hazard
3.1.3 prestressed—material in which a significant and con-
statements are given in Section 10 and A1.5, A2.3.3, A2.4.3
trolled degree of compressive stress has been deliberately
and A2.5.3.
produced in the surfaces.
3.1.4 standard laboratory atmosphere—anatmospherehav-
2. Referenced Documents
ing a temperature of 23 6 2°C and a relative humidity of 40 6
2.1 ASTM Standards:
10%.
C148 Test Methods for Polariscopic Examination of Glass
3.2 Definitions of Terms Specific to This Standard:
2
Containers
3.2.1 abraded—describes a test specimen that has at least a
3
E4 Practices for Force Verification of Testing Machines
portionoftheareaofmaximumsurfacetensilestresssubjected
to an operationally defined procedure for mechanical abrasion.
1
The severity and uniformity of abrasion should be sufficient to
These test methods are under the jurisdiction of ASTM Committee C14 on
Glass and Glass Products and are the direct responsibility of Subcommittee C14.04 ensureoriginoffailuresubstantiallyintheregionofmaximum
on Physical and Mechanical Properties.
stress.
Current edition approved Oct. 10, 2002. Published October 2002. Originally
published as C158–40T. Last previous edition C158–95(2000).
2
Annual Book of ASTM Standards, Vol 15.02.
3 4
Annual Book of ASTM Standards, Vol 03.01. Annual Book of ASTM Standards, Vol 14.04.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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C158–02
3.2.2 annealed glass—describes a specimen that shall not use identical test conditions and equivalent procedures for
have a temper or degree of residual stress resulting from prior specimen preparation to obtain comparable strength values.
thermal treatment in excess of the following limits when
The use of a controlled abrasion of the specimen as a final
measured polarimetrically (see Annex A1): normalizing procedure is recommended for such comparative
3.2.2.1 Specimens of rectangular section shall not have a
tests.
tensile stress at the midplane of more than 1.38-MPa (200-psi)
4.6 A comparative abraded strength, determined as sug-
nor more than 2.76-MPa (400-psi) compression at the surface.
gestedinTestMethodB,isnottobeconsideredasaminimum
3.2.2.2 Specimensinrodformmaybeexaminedbyviewing
valuecharacteristicofthematerialtestednorasdirectlyrelated
through a diameter at least four diameters from an end. The
to a maximum attainable strength value through test of
apparent central axial tension shall not exceed 0.92 MPa (133
specimens with
...