ASTM D7332 Measuring the Fastener Pull-Through Resistance of a Fiber Reinforced Polymer Matrix Composite

Scope:

ASTM D7332 test method can be used to perform comparative evaluations of candidate fasteners/fastener system designs. This method is consistent with the desirable attribute of a fastener pull-through as specified in CMH-17.

Procedure:

In ASTM D7332 two test procedures are present as follows.

Test Method-A (Compressive-Loaded Fixture):
Two flat square, constant rectangular cross-section composite plates, each containing a centrally located fastener hole, were placed in a multi-piece fixture that has been aligned to minimize loading eccentricities. Each plate contained four additional holes on the periphery to accommodate the test fixture components. One plate should be rotated 45° to the second plate and both were joined together by the fastener. Compressive force was applied to the plates. A tensile loading was produced through the fastener.

Test Method-B (Tensile-Loaded Fixture):
A composite plate containing a center fastener hole was placed in a multi-piece fixture. The plate was joined by the fastener to a yoke, which was designed to rotate to avoid imparting a moment to the fastener. A uniaxial tensile force was applied, a tensile loading on the fastener was imparted and an out-of-plane compressive loading on the composite plate.

For both test methods the force was applied until failure and the applied force and crosshead displacement were recorded while loading.

Read more: ASTM D7248M – 12 Bearing / Bypass Interaction Response of Polymer Matrix Composite Laminates using 2 fastener specimens.

Sample size:  

The size used for 58 HRC flat platens parallel and fixture diameter are within 0.001 and 3.75 inch, respectively. Furthermore, the total number of specimens is 5.

Results: 

For both procedures, preferred failure modes are those associated with the failure of the composite at the fastener hole. The fastener such as head, shank, or thread failure or failure of the composite away from the fastener hole is considered as an unacceptable failure mode.

Conclusion: 

ASTM D7332 test method can be used to perform comparative evaluations of candidate fasteners/fastener system designs.