SYMPOSIA PAPER Published: 01 January 1983
STP28539S

A Four-Point Shear Test for Graphite/Epoxy Composites

Source

The consistent inability of the short-beam shear (SBS) test to yield the desired interlaminar shear failure mode in thin-beam specimens of graphite/epoxy has led to the development of an alternative test method, the four-point shear (FPS) test. In the course of this developmental effort, four different shear specimens were investigated: a thin-beam 16-ply SBS specimen, a thick-beam 50-ply SBS specimen, a thin-beam 16-ply FPS specimen, and a slightly thicker 24-ply FPS specimen. All specimens were tested to failure, the resulting data were statistically analyzed, and the fractured surfaces were examined with a scanning electron microscope (SEM). The 16-ply SBS specimen never produced an interlaminar shear failure and therefore was considered unacceptable. The thick 50-ply SBS specimen consistently produced shear failure modes and corresponding failure surfaces and a very narrow data distribution. However, the thick-beam specimen is not an attractive alternative, since it poses cost and fabrication difficulties inherent to thick composites. The FPS specimen was found to be an effective alternative to the thin-beam SBS specimen. It consistently produced interlaminar shear failure modes and corresponding failure surfaces and a reasonable data distribution. In addition, the FPS specimen retains the attractive features of the thin-beam SBS specimen, being small, thin, easily machined, and employing a simplified test method. Therefore the FPS test warrants serious consideration as an alternative to the thin-beam SBS test.

Author Information

Browning, CE
Materials Laboratory, Air Force Wright Aeronautical Laboratories, Wright-Patterson Air Force Base, Ohio
Abrams, FL
Materials Laboratory, Air Force Wright Aeronautical Laboratories, Wright-Patterson Air Force Base, Ohio
Whitney, JM
Materials Laboratory, Air Force Wright Aeronautical Laboratories, Wright-Patterson Air Force Base, Ohio
Price: $25.00
Contact Sales
Related
Reprints and Permissions
Reprints and copyright permissions can be requested through the
Copyright Clearance Center
Details
Developed by Committee: D30
Pages: 54–74
DOI: 10.1520/STP28539S
ISBN-EB: 978-0-8031-4863-5
ISBN-13: 978-0-8031-0234-7