5.1 The bending fatigue test described in this test method provides information on the ability of a copper alloy flat-spring material to resist the development of cracks or general mechanical deterioration as a result of a relatively large number of cycles (generally in the range 10⁵ to 10⁸) under conditions of constant displacement.

5.2 This test method is primarily a research and development tool which may be used to determine the effect of variations in materials on fatigue strength and also to provide data for use in selecting copper alloy spring materials for service under conditions of repeated strain cycling.

5.3 The results are suitable for direct application in design only when all design factors such as loading, geometry of part, frequency of straining, and environmental conditions are known. The test method is generally unsuitable for an inspection test or a quality control test due to the amount of time and effort required to collect the data.

1.1 This test method establishes procedures for the determination of the reversed or repeated bending fatigue properties of copper alloy flat-sheet or strip-spring materials by fixed cantilever, constant deflection (that is, constant amplitude of displacement)-type testing machines. This method is limited to flat stock ranging in thickness from 0.005 to 0.062 in. (0.13 to 1.57 mm), to a fatigue-life range of 10⁵ to 10⁸ cycles, and to conditions where no significant change in stress-strain relations occurs during the test.

Note 1: This implies that the load-deflection characteristics of the material do not change as a function of the number of cycles within the precision of measurement. There is no significant cyclic hardening or softening.

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

1.3 The following safety hazard caveat pertains only to the test methods(s) described in this test method.

1.3.1 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.