ASTM D953 is a relatively bearing strength standard, 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 Fig. 1 below.



Fig. 1  ASTM D 953 Bearing Strength 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.