Stresses in fibers bridging a crack growing in center-cracked unidirectional SCS-6/TIMETAL21{reg_sign}S composite subjected to fatigue loading

Book · Sat Dec 31 04:00:00 EST 1994

OSTI ID:89828

John, R; Stibich, P R; Johnson, D A; Ashbaugh, N E; Lackey, A F ^[1]

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1. Univ. of Dayton Research Institute, OH (United States). Structural Integrity Division

This paper discusses the results of an experimental and analytical investigation of bridging fiber stress distribution for a crack growing in a TIMETAL{reg_sign}21S metal matrix composite reinforced with silicon-carbide (SCS-6) fibers. The fatigue crack growth tests were conducted at room temperature using the center-cracked tension geometry with the fibers oriented parallel to the loading direction. During the crack growth tests, crack opening displacement ranges were measured at different locations along the crack using a laser interferometric displacement gage (IDG) system. At the end of the test, residual crack opening displacements (at zero applied load) were measured using a scanning electron microscope. A procedure was developed to generate the absolute crack opening displacement profiles at different stress levels using the measured residual and laser IDG displacements. Using the weight function method, the bridging fiber stress distributions were determined by correlating the predicted and measured crack opening displacements. The results show that the absolute bridging stress and the bridging stress range distributions have different shapes. The bridging fiber stress distribution at the maximum applied fatigue stresses are non-uniform, increasing rapidly from a low value at the crack tip to near-constant away from the crack tip. The bridging fiber stress range is near-linear with non-zero stresses at the crack tip. The magnitude of the bridging stress range is proportional to the applied load.

• OSTI ID: 89828
• Report Number(s): CONF-9409291--; ISBN 1-56676-220-0
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
COMPOSITE MATERIALS
CRACK PROPAGATION
CRACKS
EXPERIMENTAL DATA
FATIGUE
FRACTURE MECHANICS
INTERFEROMETRY
LASERS
MATHEMATICAL MODELS
NOTCHES
RESIDUAL STRESSES
SCANNING ELECTRON MICROSCOPY
SILICON CARBIDES
STRESSES
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