ASTM D 953 BEARING STRENGTH TEST FIXTURE
(ASTM D 953)

Model No. CU-LB-D953  (low carbon steel)
Model No. WTF-LB-D953  (17-4PH stainless)

ASTM D 953 is a relatively old bearing strength standard (originally published in 1948), intended for testing rigid plastics, as its title implies (see Reference 1).  This standard actually contains both tensile-mode and compressive-mode loading fixtures, although the latter fixture is seldom used.  The standard tensile loading fixture is shown in the photograph below. 

ASTM D 953 Test Fixture

The standard specimen is 4.75” long, 0.938” wide, and of a thickness equal to the diameter of the fastener hole used, viz., either 1/8” or 1/4”.  Since the fastener hole sizes are different, two different fixtures must be used.  A ¼” diameter fastener is more commonly used.

Although originally developed for unreinforced plastics, this test fixture is sometimes used to test composites and other materials also, typically using the ¼” diameter fastener configuration.  And the condition specified in ASTM D 953 that the specimen thickness is to be equal to the fastener diameter is often not maintained when testing these other materials.  That is, non-conforming tests are often conducted, as for example are reported in Reference 2.

Alternate standards for bearing strength testing are also available, with alternate fixture configurations.  See, for example, Sections H-2 and H-3 of this catalog (corresponding to References 3 and 4).  These may be more suitable for a particular application.

Sources of Additional Information:

1)     1)  ASTM Standard D 953-95 (1995), "Bearing Strength of Plastics," American Society for Testing and Materials, West Conshohocken, Pennsylvania (first issued in 1948). 

2)     2)  M. Akay, “Bearing Strength of As-Cured and Hygrothermally Conditioned Carbon Fibre/Epoxy Composites Under Static and Dynamic Loading,” Composites, Vol. 23, No. 2, March 1992, pp. 101-108.

3)     3)  SACMA Recommended Method SRM 9-89, "Bearing Strength Properties of Oriented Fiber-Resin Composites," Suppliers of Advanced Composite Materials Association, Arlington, Virginia, 1989 (now discontinued).

4)     4)   ASTM Standard D5961/D5961M-96 (1996), "Bearing Response of Polymer Matrix Composite Laminates," American Society for Testing and Materials, West Conshohocken, Pennsylvania (first issued in 1996).