ASTM B593-96(2003)e1
(Test Method)Standard Test Method for Bending Fatigue Testing for Copper-Alloy Spring Materials
Standard Test Method for Bending Fatigue Testing for Copper-Alloy Spring Materials
SIGNIFICANCE AND USE
The flexural 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.
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.
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.
SCOPE
1.1 This test method describes 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 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 10 5 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 UnitsThe values stated in inch-pound units are regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information purposes 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 and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: B 593 – 96 (Reapproved 2003)
Standard Test Method for
Bending Fatigue Testing for Copper-Alloy Spring Materials
This standard is issued under the fixed designation B 593; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number 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.
e NOTE—Paragraph 1.2 was updated editorially in January 2004.
1. Scope* 4. Summary of Test Method
1.1 This test method describes procedures for the determi- 4.1 A prepared test specimen of a specific wrought copper
nation of the reversed or repeated bending fatigue properties of alloy flat-sheet or strip-spring material is mounted into a fixed
copper alloy flat-sheet or strip-spring materials by fixed canti- cantilever, constant-deflection type fatigue testing machine.
lever, constant amplitude of displacement-type testing ma- The specimen is held at one end, acting as a cantilever beam,
chines.This method is limited to flat stock ranging in thickness and cycled by flexure followed by reverse flexure until
from 0.005 to 0.062 in. (0.13 to 1.57 mm), to a fatigue-life complete failure.The number of cycles to failure is recorded as
5 8
range of 10 to 10 cycles, and to conditions where no a measure of fatigue-life.
significant change in stress-strain relations occurs during the
5. Significance and Use
test.
5.1 The flexural fatigue test described in this test method
NOTE 1—This implies that the load-deflection characteristics of the
provides information on the ability of a copper alloy flat-spring
material do not change as a function of the number of cycles within the
material to resist the development of cracks or general me-
precision of measurement. There is no significant cyclic hardening or
chanicaldeteriorationasaresultofarelativelylargenumberof
softening.
5 8
cycles (generally in the range 10 to 10 ) under conditions of
1.2 Units—The values stated in inch-pound units are re-
constant displacement.
garded as standard. The values given in parentheses are
5.2 This test method is primarily a research and develop-
mathematical conversions to SI units that are provided for
ment tool which may be used to determine the effect of
information purposes only and are not considered standard.
variations in materials on fatigue strength and also to provide
1.3 This standard does not purport to address all of the
data for use in selecting copper alloy spring materials for
safety concerns, if any, associated with its use. It is the
service under conditions of repeated strain cycling.
responsibility of the user of this standard to establish appro-
5.3 The results are suitable for direct application in design
priate safety and health practices and determine the applica-
only when all design factors such as loading, geometry of part,
bility of regulatory limitations prior to use.
frequency of straining, and environmental conditions are
known. The test method is generally unsuitable for an inspec-
2. Referenced Documents
tion test or a quality control test due to the amount of time and
2.1 ASTM Standards:
effort required to collect the data.
E 206 Definitions of Terms Relating to Fatigue Testing and
the Statistical Analysis of Fatique Data
6. Apparatus
E 468 Practice for Presentation of Constant Amplitude Fa-
3 6.1 Testing Machine—The fatigue testing machine is a
tigue Test Results for Metallic Materials
fixed-cantilever, constant-deflection type. In this machine (Fig.
1) the test specimen shall be held as a cantilever beam in a
3. Terminology
clamp at one end and deflected by a concentrated load applied
3.1 For terminology relating to this test method, refer to
near the other end of the apex of the tapered section (Fig. 2).
Definitions E 206 and Practice E 468.
Either the clamp or the loading member may be adjusted so
that the deflection of the free end of the cantilever is either
This test method is under the jurisdiction ofASTM Committee B05 on Copper
completely reversed (mean displacement equal to zero) or
and Copper Alloys and is the direct responsibility of Subcommittee B05.06 on
greater in one direction of bending (mean displacement not
Methods of Test.
Current edition approved Apr. 10, 2003. Published June 2003. Originally
equal to zero).
approved in 1973. Last previous edition approved in 1996 as B593 – 96.
Discontinued, see 1986 Annual Book of ASTM Standards, Vol 03.01.
Annual Book of ASTM Standards, Vol 03.01.
*A Summary of Changes section appears at the end of this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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B 593 – 96 (2003)
FIG. 1 Fatigue Machines
6.2 A suitable counter and monitoring circuit is required to this tends to give an apparent higher fatigue strength. Burrs,
provide a direct readout of the number of cycles to complete however, may be removed by light stoning.
failure, that is, separation into two pieces. 7.4 Test specimens from material that is used in a thermally
treated condition, such as precipitation hardened or stress
7. Test Specimen
relieved, shall be treated in a manner reflecting the way the
7.1 The test specimen shall be of the fixed-cantilever type.
material will be used. The procedure used should be noted in
Several such specimens which have been used successfully are
reporting test results.
shown in Fig. 2.
8. Calculation of Stress
7.2 It is important, therefore, that care be exercised in the
preparation of test specimens, particularly in machining, to
8.1 The maximum bending stress is calculated by using the
assure good workmanship. Improperly prepared test specimens
simple beam equation:
cause unsatisfactory test results.
S 5 6PL/bd (1)
7.2.1 The specimens are best prepared by cross milling a
stack,approximately0.75in.(19mm)thick,includingback-up
where:
plates, for which 0.12-in. (3-mm) thick brass sheet stock may
S = desired bending stress, lb/in. ,
be used. P = applied load at the connecting pin (apex of triangle), lb,
L = distance between the connecting pin and the point of
7.2.1.1 It is necessary to ensure that any cutting or machin-
ing operation required to either rough cut the test specimen stress, in.,
b = specimen wi
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