Orientation effects on the measurement and analysis of critical CTOA in an aluminum alloy sheet

Conference · Sun Dec 31 04:00:00 EST 1995

OSTI ID:597673

Sutton, M A ^[1]; Dawicke, D S ^[2]; Newman, Jr, J C ^[3]

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1. Univ. of South Carolina, Columbia, SC (United States). Dept. of Mechanical Engineering
2. Analytical Services and Materials, Inc., Hampton, VA (United States)
3. National Aeronautics and Space Administration, Hampton, VA (United States). Langley Research Center

Fracture tests were conducted on 76.2 mm wide, 2.3 mm thick middle crack tension (M(T)) specimens machined from 2024-T3 aluminum sheet. The specimens were tested in the T-L orientation and comparisons were made to similar tests conducted in the L-T orientation. Measurement of critical crack tip opening angle (CTOA), applied stress, and crack front shape were made as a function of crack extension. A two-dimensional, elastic-plastic finite element analysis was used to simulate the fracture behavior for both orientations. The results indicate that the T-L orientation had a 10% lower stress at fracture than similar tests conducted in the L-T orientation. Correspondingly, the critical CTOA in the T-L tests reached a constant value of 4.7{degree} after 2--3 mm of crack extension and the L-T tests reached a value of 6{degree}. The fracture surface of the T-L specimens were observed to remain flat, while those of the L-T specimens transitioned to a 45{degree} slant fracture after about 2--3 mm of crack extension. The tunneling behavior of the two orientations also differed; the T-L specimens reached a deeply tunneled stabilized crack front shape, while the L-T specimens were observed to have only a small amount of tunneling once the crack began to grow on the 45{degree} slant. The two-dimensional, elastic-plastic finite element analysis was able to simulate the fracture behavior for both the T-L and L-T orientations.

• OSTI ID: 597673
• Report Number(s): CONF-9406335--
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM BASE ALLOYS
CRACK PROPAGATION
FRACTURE MECHANICS
MECHANICAL TESTS
ORIENTATION
STRESSES
TWO-DIMENSIONAL CALCULATIONS