SYMPOSIA PAPER Published: 01 January 1989

Elastic-Plastic Stress Concentrations Around Crack-like Notches in Continuous Fiber Reinforced Metal Matrix Composites


Continuous fiber silicon-carbide/aluminum composite laminates with slits were tested statically to failure. Five different layups were examined: [0]8, [02/±45]s, [0/90]2s, [0/±45/90]s, and [±45]2s. Either a 9.5- or a 19-mm slit was machined in the center of each specimen. The strain distribution ahead of the slit tip was found experimentally with a series of strain gages bonded ahead of the slit tip. A three-dimensional finite-element program (PAFAC) was used to predict the strain distribution ahead of the slit tip for several layups. For all layups, except the [0]8, the yielding of the metal matrix caused the fiber stress concentration factor to increase with increasing load. This is contrary to the behavior seen in homogeneous materials where yielding causes the stress concentration to drop. For the [0]8 laminate, yielding of the matrix caused a decrease in the fiber stress concentration. The finite-element analysis predicted these trends correctly.

Author Information

Johnson, WS
NASA Langley Research Center, Hampton, VA
Bigelow, CA
NASA Langley Research Center, Hampton, VA
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Developed by Committee: D30
Pages: 261–275
DOI: 10.1520/STP10031S
ISBN-EB: 978-0-8031-5071-3
ISBN-13: 978-0-8031-1196-7