Significance and Use
5.1 The bending fatigue test described in this test method provides information on the ability of a copper alloy flat sheet and strip of 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 the requirements for the determination of the reversed or repeated bending fatigue properties of copper alloy flat sheet or strip of spring materials by fixed cantilever, constant deflection (that is, constant amplitude of displacement)-type testing machines. This method is limited to flat sheet or strip ranging in thickness from 0.005 in. to 0.062 in. (0.13 mm 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. The values given in parentheses are mathematical conversions to SI units that 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, 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.