Effects of stress ratio and fiber orientation on fatigue crack growth behavior in APAL

Conference · Fri Dec 31 04:00:00 EST 1993

OSTI ID:402992

Oh, S W; Park, W J ^[1]; Yoon, H K; Lee, K G ^[2]; Cho, J M; Lee, K B ^[3]

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1. Dong-A Univ., Pusan (Korea, Republic of). Dept. of Mechanical Engineering
2. Dong-Eui Univ., Pusan (Korea, Republic of). Dept. of Mechanical Engineering
3. Han Kuk Fiber Glass Co. Ltd., Kyungnam (Korea, Republic of)

A new hybrid composite (APAL; Aramid Patched Aluminum Alloy), consisting of 2024-T3 aluminum alloy plate sandwiched between aramid/epoxy prepregs (HK 285/RS 1222), was developed. Fatigue crack growth behavior was examined at stress ratios of R = 0.2, 0.5 using two kinds of APAL with different fiber orientation (0{degree}/90{degree} and {+-} 45{degree} for crack direction). The APAL showed superior fatigue crack growth resistance, which may be attributed to the crack bridging effect imposed by the intact fibers in the crack wave. The magnitude of crack bridging was estimated quantitatively and determined by a new technique on the basis of the compliances of 2024-T3 aluminum alloy and APAL specimens. The crack growth rate of the APAL specimens was reduced significantly as comparison to the monolithic aluminum alloy and was not adequately correlated with the conventional stress intensity factor range ({Delta}K). It was found that the crack growth rate was successfully correlated with the effective stress intensity factor range ( {Delta}K{sub eff} = K{sub br} {minus} K{sub cl}) allowing for the crack closure and the crack bridging. The relation between da/dN and {Delta}K{sub eff} was plotted within a narrow scatter band regardless at loading line of 2024-T3 aluminum alloy, two kinds of the APAL (APAL 0{degree}/90{degree}, APAL {+-} 45{degree}) and two kinds of stress ratios (R = 0.2, 0.5).

• OSTI ID: 402992
• Report Number(s): CONF-940473--; ISBN 1-880653-15-X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
42 ENGINEERING
ALUMINIUM ALLOYS
CRACK PROPAGATION
FATIGUE
FRACTURE MECHANICS
MATERIALS
MATERIALS TESTING
OFFSHORE PLATFORMS
STRESS INTENSITY FACTORS