SYMPOSIA PAPER Published: 01 January 1986

Residual Strength of Five Boron/Aluminum Laminates with Crack-Like Notches After Fatigue Loading


Boron/aluminum specimens were made with crack-like slits in the center and with various proportions of 0° and ±45° plies. They were fatigue loaded and then fractured to determine their residual strengths. The fatigue loads were generally in the range of 60 to 80% of the static tensile strength of the specimen as determined from a previous study, and the stress ratio was 0.05. For virtually all of the specimens the fatigue loading was continued for 100 000 cycles. The spcimens were radiographed after the fatigue loading to determine the nature of the fatigue damage. A few specimens were sectioned and examined in a scanning electron microscope after being radiographed in order to verify the interpretation of the radiographs and also to get a better insight into the nature of the fatigue damage.

The results indicate that the fatiguing does not significantly affect the strength of the specimens tested. The results of the radiography and of the scanning electron microscopy indicate that the 45° plies suffer extensive damage in the form of split and broken fibers and matrix cracking in the vicinity of the ends of the slit. By contrast, the only significant damage to the 0° plies was a single 0° matrix crack growing from the ends of the slit.

Author Information

Simonds, RA
Virginia Polytechnic Institute and State University, Blacksburg, VA
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Developed by Committee: E08
Pages: 136–152
DOI: 10.1520/STP17393S
ISBN-EB: 978-0-8031-4972-4
ISBN-13: 978-0-8031-0472-3