Fatigue Growth and Closure of Short Cracks
Final rept. Jun 1985-Dec 1988
VIRGINIA POLYTECHNIC INST AND STATE UNIV BLACKSBURG
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A study has been carried out to investigate the growth and closure behavior of short cracks in 2024-T351 aluminum alloy and four different conditions of 4340 steel using through thickness cracks of straight fronts. The experiments were carried out to study the influence of stress level, stress ratio, yield strength and prior austenitic grain sizes in notched and unnotched specimens. The stereoimaging technique was developed and adapted to obtain crack closing and opening points, and also near tip displacement fields. Experimental results are presented with a general discussion. It was found that long cracks showed good correlation when analyzed in terms of effective stress intensity range. However, correlations were poor for short cracks. It was found that short cracks show less closure behavior than long cracks. The estimates of initial crack lengths based on linear elastic data were made. Short cracks, Crack closure, fracture mechanics, Crack growth rate, Stereoimaging, Durability damage tolerance.
- Metallurgy and Metallography