ASTM C158-02(2012)
Standard Test Methods for Strength of Glass by Flexure (Determination of Modulus of Rupture)

Standard No.

ASTM C158-02(2012)

Release Date

2002

Published By

American Society for Testing and Materials (ASTM)

Status

Be replaced

Replace By

ASTM C158-02(2017)

Latest

ASTM C158-23

Scope

4. Significance and UseTop Bottom

4.1 For the purpose of this test, glasses and glass-ceramics are considered brittle (perfectly elastic) and to have the property that fracture normally occurs at the surface of the test specimen from the principal tensile stress. The modulus of rupture is considered a valid measure of the tensile strength subject to the considerations discussed below.

4.2 It is recognized that the modulus of rupture for a group of test specimens is influenced by variables associated with the test procedure. These include the rate of stressing, test environment, and the area of the specimen subjected to stress. Such factors are specified in the test procedure or required to be stated in the report.

4.3 It is also recognized that the variables having the greatest effect on the modulus of rupture value for a group of test specimens are the condition of the surfaces and glass quality near the surfaces in regard to the number and severity of stress-concentrating discontinuities or flaws, and the degree of prestress existing in the specimens. Each of these can represent an inherent part of the strength characteristic being determined or can be a random interfering factor in the measurement.

4.4 Test Method A is designed to include the condition of the surface of the specimen as a factor in the measured strength. It is, therefore, desirable to subject a fixed and significant area of the surface to the maximum tensile stress. Since the number and severity of surface flaws in glass are primarily determined by manufacturing and handling processes, this test method is limited to products from which specimens of suitable size can be obtained with minimal dependence of measured strength upon specimen preparation techniques. This test method is therefore designated as a test for modulus of rupture of flat glass.

4.5 Test Method B describes a general procedure for test, applicable to specimens of rectangular or elliptical cross section. This test method is based on the assumption that a comparative measurement of strength on groups of specimens is of significance for many purposes, such as determining the effect of environment or stress duration, or the effectiveness of varied prestressing techniques or strengths characteristic of glass-ceramics of differing composition or heat treatment. In this test method the surfaces of the specimens are not assumed to be characteristic of a product or material, but are considered to be determined by the procedures used to prepare the specimens. Though the stated procedure permits a wide variation in both specimen size and test geometry, it is necessary to use identical test conditions and equivalent procedures for specimen preparation to obtain comparable strength values. The use of a controlled abrasion of the specimen as a final normalizing procedure is recommended for such comparative tests.

4.6 A comparative abraded strength, determined as suggested in Test Method B, is not to be considered as a minimum value characteristic of the material tested nor as directly related to a maximum attainable strength value through test of specimens with identical flaws. The operationally defined abrasion procedure un..........

ASTM C158-02(2012) Referenced Document

• ASTM C148 Standard Test Methods for Polariscopic Examination of Glass Containers
• ASTM E4 Standard Practices for Force Verification of Testing Machines

ASTM C158-02(2012) history

• 2023 ASTM C158-23 Standard Test Methods for Strength of Glass by Flexure (Determination of Modulus of Rupture)
• 2002 ASTM C158-02(2017) Standard Test Methods for Strength of Glass by Flexure (Determination of Modulus of Rupture)
• 2002 ASTM C158-02(2012) Standard Test Methods for Strength of Glass by Flexure (Determination of Modulus of Rupture)
• 2002 ASTM C158-02(2007) Standard Test Methods for Strength of Glass by Flexure (Determination of Modulus of Rupture)
• 2002 ASTM C158-02 Standard Test Methods for Strength of Glass by Flexure (Determination of Modulus of Rupture)
• 2000 ASTM C158-95(2000) Standard Test Methods for Strength of Glass by Flexure (Determination of Modulus of Rupture)
• 2000 ASTM C158-95 Standard Test Methods for Strength of Glass by Flexure (Determination of Modulus of Rupture)