ASTM D953-95

Standard Test Method for Bearing Strength of Plastics

SCOPE
1.1 This test method covers the determination of the bearing strength of rigid plastics in either sheet or molded form. Procedure A is applicable for tension loading and Procedure B for compression loading.
1.2 Test data obtained by this test method is relevant and appropriate for use in engineering design.
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.4 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.Note 1—There is no known ISO equivalent to this standard.

General Information

• Status: Historical
• Publication Date: 09-Apr-2002
• ICS: 83.080.01 - Plastics in general
• Technical Committee: D20 - Plastics
• Drafting Committee: D20.10 - Mechanical Properties

Relations

• Replaced By: ASTM D953-02 - Standard Test Method for Bearing Strength of Plastics
• Effective Date: 10-Apr-2002
• Referred By: ASTM F790-23 - Standard Guide for Testing Materials for Aerospace Plastic Transparent Enclosures
• Effective Date: 10-Apr-2002
• Referred By: ASTM D5961/D5961M-23 - Standard Test Method for Bearing Response of Polymer Matrix Composite Laminates
• Effective Date: 10-Apr-2002
• Referred By: ASTM D7745-19 - Standard Practice for Testing Pultruded Composites
• Effective Date: 10-Apr-2002
• Referred By: ASTM D4762-18 - Standard Guide for Testing Polymer Matrix Composite Materials
• Effective Date: 10-Apr-2002

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
An American National Standard
Designation: D 953 – 95
Standard Test Method for
Bearing Strength of Plastics
This standard is issued under the fixed designation D 953; 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.
1. Scope or Terminology D 4805.
3.2 Definitions of Terms Specific to This Standard:
1.1 This test method covers the determination of the bearing
3.2.1 bearing area—the diameter of the hole multiplied by
strength of rigid plastics in either sheet or molded form.
the thickness of the specimen.
Procedure A is applicable for tension loading and Procedure B
3.2.2 bearing strength—the bearing stress at which the
for compression loading.
bearing hole is deformed 4 % of its diameter.
1.2 Test data obtained by this test method is relevant and
3.2.3 bearing stress—the applied load in newtons (or
appropriate for use in engineering design.
pounds-force) divided by the bearing area.
1.3 The values stated in SI units are to be regarded as the
3.2.4 edge distance ratio—the distance from the center of
standard. The values given in parentheses are for information
the bearing hole to the edge of the specimen in the direction of
only.
the principle stress, divided by the diameter of the hole.
1.4 This standard does not purport to address all of the
3.2.5 maximum bearing stress—the maximum load in new-
safety concerns, if any, associated with its use. It is the
tons (or pounds-force) sustained by the specimen, divided by
responsibility of the user of this standard to establish appro-
the bearing area.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
4. Significance and Use
2. Referenced Documents 4.1 This bearing strength test for plastics is intended to
apply in the specification of various thermoplastic or thermo-
2.1 ASTM Standards:
setting products in sheet form where rivets, bolts, or similar
D 618 Practice for Conditioning Plastics and Electrical
fastenings are to be used in joining members or sections. It also
Insulating Materials for Testing
is intended to apply wherever sheet materials of the classes
D 883 Terminology Relating to Plastics
indicated are required to sustain edgewise loads that are
D 4000 Classification System for Specifying Plastic Mate-
applied by means of pins or rods of circular cross section which
rials
pierce the sheet perpendicular to the surface.
D 4066 Specification for Nylon Injection and Extrusion
4.2 The purpose of the test is to determine the bearing
Materials
strength of the material and to show the bearing stress versus
D 4805 Terminology of Plastics Standards
5 the deformation of the hole. The allowable deformation of the
E 4 Practices for Load Verification of Testing Machines
hole in the material should be such as to produce no looseness
E 6 Terminology Relating to Methods of Mechanical Test-
5 of joints.
ing
4.3 While it is a known fact that higher strength materials
3. Terminology will generally give higher bearing strengths, there is no
satisfactory method by which bearing strength may be esti-
3.1 Definitions—For definitions of technical terms pertain-
mated from tensile or compressive properties of the material.
ing to plastics used in this test method, see Terminology D 883
4.4 For many materials, there may be a specification that
requires the use of this test method, but with some procedural
This test method is under the jurisdiction of ASTM Committee D-20 on Plastics
modifications that take precedence when adhering to the
and is the direct responsibility of Subcommittee D20.10 on Mechanical Properties.
specification. Therefore, it is advisable to refer to that material
Current edition approved Oct. 10, 1995. Published December 1995. Originally
published as D 953 – 48 T. Last previous edition D 953 – 93.
Annual Book of ASTM Standards, Vol 08.01.
Annual Book of ASTM Standards, Vol 08.02.
Annual Book of ASTM Standards, Vol 08.03.
5 6
Annual Book of ASTM Standards, Vol 03.01. Attention is also directed to Terminology E 6.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 953
specification before using this test method. Table 1 of Classi-
fication System D 4000 lists the ASTM materials standards that
currently exist.
5. Apparatus
5.1 Testing Machine—A properly calibrated universal test-
ing machine that can be operated at a speed of 1.3 6 0.3 mm
(0.05 6 0.01 in.)/min, except that in cases of certain types of
material it may be necessary to operate at a slower speed. The
percentage of error of the testing machine shall be no more
than 61 % of the applied load as determined in accordance
with Practices E 4.
5.2 Tension Loading Fixture—A three-plate fixture of hard-
ened steel similar to that shown in Fig. 1.
5.3 Extension Indicator—A suitable instrument reading in
0.0025 mm (0.0001 in.) for indicating the movement of the free
end of the specimen with relation to the bearing pin in the
tension loading fixture. A dial gage fitted with accessories for
this purpose is shown in Fig. 2.
5.4 Compression Loading Fixture—A type of support with a
suitable bearing pin similar to Fig. 3.
5.5 Compression Indicator—A suitable instrument reading
to 0.0025 mm (0.0001 in.) for indicating the movement of the
free end of the specimen with relation to the bearing pin in the
1—Spacer plate.
2—Dial gage.
3—Double foot ring mounted on spindle of dial gage.
4—Bearing pin.
5—Yoke mounted on specimen.
6—Test specimen.
7—Plan view of yoke.
FIG. 2 Tension Loading Assembly
compression loading fixture. A suggested dial gage assembly
for this purpose is shown in Fig. 4.
6. Test Specimens
6.1 The test specimens shall conform to the dimensions
shown in Fig. 5. A size of test specimen shall be chosen that
most nearly conforms to production requirements of the
material and the type of loading under consideration. The
1—Hardened spacer plate.
2—6.3-mm (-in.) steel bolts in reamed holes.
thicker specimens with the larger bearing hole are likely to give
3—Hardened side plate.
the more precise results, although it is advantageous to use the
4—Extensometer span.
thinner specimens with the smaller bearing hole in testing
5—Hardened steel pin in reamed hole.
6—Test specimen.
certain relatively brittle plastics because they are less likely to
fail prematurely. The specimen may be machined from sheet or
Note—Critical dimensions are as follows:
molded to finished size. The bearing hole shall be located as
Thickness of
Bearing Hole Diam- Bearing Pin Diameter, mm
shown in Fig. 5. It shall be drilled undersized and reamed to
Type Spacer Plate,
eter, mm (in.) (in.)
A
mm (in.) size as indicated. The hole shall be clean and smooth with
sharp edges but not polished. It is suggested that the reaming
I 3.175 + 0.025 3.150 + 0.000 3.2
− 0.000 − 0.025
operation be done in the drill press by hand without the use of
(0.125 + 0.0010 (0.124 + 0.0000 ( ⁄8)
a jig.
− 0.0000) − 0.0010)
II 6.350 + 0.025 6.325 + 0.000 6.3
7. Number of Test Specimens
− 0.000 − 0.025
(0.250 + 0.0010 (0.249 + 0.0000 ( ⁄4)
7.1 At least five specimens shall be tested for each sample in
− 0.0000) − 0.0010)
the case of isotropic materials.
7.2 Ten specimens, five perpendicular to and five parallel
A
The spacer plate shall be shimmed to a thickness of 0.025 to 0.125 mm (0.001
with the principal axis of anisotropy, shall be tested for each
to 0.005 in.) greater than the specimen under test.
FIG. 1 Steel Tension Loading Fixture sample in case of anisotropic materials.
D 953
specimens shall not exceed 1.3 6 0.3 mm (0.05 6 0.01
in.)/min. In any case the crosshead movement shall be slow
enough so that deflection gage readings can be made accu-
rately.
11. Procedure
11.1 The choice of either Procedure A for tension loading
(11.2) or Procedure B for compression loading (11.3) is
optional, but it should be recognized that Procedure B gives
1—Test specimen.
higher bearing strength values than Procedure A on the same
2—Hardened steel pin.
material. Test specimens according to both Procedures A and B
3—Hardened thrust bushing.
if a complete specification of bearing strength is required.
Note—Critical dimensions are as follows:
11.2 Procedure A for Tension Loading—Mount the speci-
Minimum
men to be tested in the tension loading fixture and attach a
Clear-
Bearing Hole Diam-
deformation indicator. If a dial gage (Fig. 2) is used, adjust the
Bearing Pin Diameter, ance Be-
Type eter,
mm (in.) tween
yoke so that contact is made with the specimen at the level
mm (in.)
Bushings,
indicated in Fig. 1. Exception is taken in the case of those
mm (in.)
thermoplastic materials which exhibit extended plastic flow.
I 3.175 + 0.025 3.150 + 0.000 2.8
Such specimens tend to “neck down” in the region of the
− 0.000 − 0.025
(0.125 + 0.0010 (0.124 + 0.000
...