4.1 Measurements of bending proof strength, offset yield strength in bending, and modulus of elasticity in bending should be made for materials whose principal stressing mode is bending. For many materials, the tensile and compressive moduli are somewhat different. Since the modulus of elasticity in bending is a combination of the tensile and compressive moduli, it is often different from each of them.

4.2 Precise measurements of the modulus of elasticity in bending offset yield strength in bending, and bending proof strength require due regard for numerous variables that can affect their determination. These include (1) material characteristics such as specimen orientation with respect to the rolling direction, grain size, residual stresses, previous strain history, dimensions and specimen preparation, orientation of deformed grains relative to the direction of the normal stress; and (2) test conditions, such as temperature, temperature variations, condition of the test equipment, and adherence to the test procedure.

4.3 Fundamental Assumptions: 

4.3.1 The test section of the specimen is subjected to uniform bending moment, which produces a uniform strain at the outer fiber throughout the gauge length of the specimen (applies to Test Method C only).

4.3.2 The neutral axis is located at the centerline of the thickness of the test specimen.

4.3.3 Transverse cross sections of the beam remain plane and normal to the longitudinal fiber of the beam during bending.

4.3.4 The effect of shear stresses is negligible.

1.1 This standard describes three test methods2 for determining the modulus of elasticity in bending, the bending proof strength, and the offset yield strength in bending of metallic strips or sheets intended for the use in flat springs:

1.1.1 Test Method A—a cantilever beam test,

1.1.2 Test Method B—a three-point beam test (that is, a beam resting on two supports and centrally loaded), and

1.1.3 Test Method C—a four-point beam test (that is, a beam resting on two supports and loaded at two points equally spaced from each support).

1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.

1.3 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.