ASTM D7107-04(2010)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:D7107 −04(Reapproved 2010)
Standard Test Method for
Creep Measurement of Self-Lubricating Bushings
This standard is issued under the fixed designation D7107; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope 4. Significance and Use
1.1 This test method determines the amount of creep exhib- 4.1 Self-lubricating bushings with low creep rates are used
ited by self-lubricating bushings exposed to a high load for an in hydropower turbines and other applications in which bush-
extended period of time. ing distortion could cause misalignment of shafts and linkages.
1.2 This test method is designed to reproduce conditions 4.2 An assumption is made that if the creep is satisfactory at
typical of those encountered by trunnion bushings in hydro- 55 160 kPa (8000 psi), it will also be satisfactory at lower
power applications and any other bushings subjected to high pressures.
continuous loading and low-speed oscillating applications.
5. Apparatus
1.3 This test method is conducted on cut segments of the
5.1 The loading frame shall be capable of applying and
bushings.
maintaining the required load on the specimens, despite any
1.4 The values given in SI units are to be regarded as the
change in the dimensions of the specimens.
standard in all property and dimensional tables.
5.2 Bushing specimens are mounted in-line on the test
1.5 This standard does not purport to address all of the
apparatus such that when load is applied at one end of the
safety concerns, if any, associated with its use. It is the
apparatus (by means of a hydraulic cylinder) all specimens
responsibility of the user of this standard to establish appro-
receive the same load.
priate safety and health practices and to determine the
5.3 Bearing test pressure is maintained at 55 160 kPa (8000
applicability of regulatory limitations prior to use.
psi) on the projected area of the bushing specimen.
NOTE 1—There is no known ISO equivalent to this standard.
5.4 Pressure is held (nearly) constant by means of an
2. Terminology automatic pumping system and an accumulator.
2.1 Definitions of Terms Specific to This Standard: 5.5 A suitable test frame configuration is shown in Annex
2.1.1 creep strain, n—total strain, at any given time, pro- A1.
duced by the applied stress during a creep test.
5.6 The creep-measuring device consists of an eddy-current
sensor anchored to one end of a specimen group (four test
3. Summary of Test Method
samples) directed at a target attached to the other end of the
3.1 Segments of the bushing are mounted in-line on the test
group.
apparatus such that when load is applied at one end of the
5.7 The overall change in lengths of the four specimens is
apparatus, by means of a hydraulic cylinder, all specimens are
monitored to an accuracy of 2.54 µm (0.0001 in.).
simultaneously loaded exactly the same.
6. Test Specimens and Test Units
3.2 Bearing test pressure is maintained at 55 160 kPa (8000
psi) on the projected area of the bushing specimen.
6.1 Paragraph 6.2 and Fig. 1 define the test sample configu-
ration. The samples are clamped into sample supports as
3.3 Pressure is held constant by means of an automatic
described in Section 7.
pumping system and an accumulator.
6.2 Each test shall use four identical bushing material
3.4 The actual amount of creep is measured over an ex-
specimens meeting the following requirements (reference Fig.
tended period of time.
1):
6.2.1 Inside Radius of Tubular Form—6.350 6 0.013 cm
This test method is under the jurisdiction ofASTM Committee D20 on Plastics
(2.500 6 0.005 in.),
and is the direct responsibility of Subcommittee D20.10 on Mechanical Properties.
6.2.2 Thickness—0.952 6 0.005 cm (0.375 6 0.002 in.),
Current edition approved Nov. 1, 2010. Published March 2011. Originally
6.2.3 Length—6.98 + 0.000/-0.013 cm (2.75 + 0.000/-0.005
approved in 2004. Last previous edition approved in 2004 as D7107 - 04. DOI:
10.1520/D7107-04R10. in.),
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7107−04 (2010)
FIG. 1Test Sample Configuration
6.2.4 Angle of Arc (Each Finished Specimen)—120 6 1.0°, 7.1.3 Length—6.985 + 0.000/-0.025 cm (2.75 + 0.000/-
and 0.010 in.),
6.2.5 Surface Finish—R 3.2 µm (125 µin.) minimum. 7.1.4 Perpendicularity—Ends perpendicular with cylinder
a
axis within 50 µm (0.002 in.), and
7. Preparation of Apparatus 7.1.5 Surface Finish—R 0.4 µm (16 µin.) minimum.
a
7.1 Sample Spacer: 7.2 Sample Supports:
7.1.1 Material and Temper—AL 6061 T6 or T6511, 7.2.1 Material and Temper—AL 6061 T6 or T6511,
7.1.2 Diameter—2.700 6 0.005 cm (5.000 6 0.002 in.), 7.2.2 Radii—7.302 6 0.025 cm (2.875 6 0.010 in.),
D7107−04 (2010)
7.2.3 Length—6.985 + 0.0
...