Microcrack formation of IM6/E773 graphite/epoxy cross-ply laminates

Book · Sat Dec 31 04:00:00 EST 1994

OSTI ID:89787

Peters, J C ^[1]; Chan, W S ^[2]

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1. PPG Industries, Inc., Shelby, NC (United States)
2. Univ. of Texas, Arlington, TX (United States). Dept. of Mechanical and Aerospace Engineering

Microcracking was examined in a graphite/epoxy laminate utilizing both (0{sub 2}, 90{sub 2}){sub s} and (90{sub 2}, 0{sub 2}){sub s}, lay-ups. Growth of microcracking was monitored using x-ray or acoustic emission detection techniques. A subsequent failure analysis was performed using optical and scanning electron microscopy (SEM). Microcracking was determined to be a static occurrence, during both static and fatigue loadings, which progressed completely through the 90{degree} plies. Static testing produced minor interlaminar cracking at the 0{degree}--90{degree} interface in the (90{sub 2}, 0{sub 2}){sub s} specimens. Optical microscopy at high magnifications revealed small resin cracking near the tip of the microcrack which was consistent with an interlaminar stress concentration between the 0{degree} and 90{degree} plies. These cracks were observed at the 0{degree}--90{degree} interface in both samples. Fatigue testing produced delaminations, due to interlaminar stresses, at the 0{degree}--90{degree} interfaces. SEM examination revealed evidence of fatigue progression. Strain energy release rate calculations found the (90{sub 2}, 0{sub 2}){sub s} specimens to be more susceptible to microcracking.

• OSTI ID: 89787
• Report Number(s): CONF-9409291--; ISBN 1-56676-220-0
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ACOUSTIC EMISSION TESTING
CARBON FIBERS
COMPOSITE MATERIALS
CRACK PROPAGATION
EPOXIDES
EXPERIMENTAL DATA
FATIGUE
FRACTURE MECHANICS
OPTICAL MICROSCOPY
SAMPLE PREPARATION
SCANNING ELECTRON MICROSCOPY
X-RAY RADIOGRAPHY