SEDL / STP / STP631-EB / STP35542S

Effect of Specimen Size on J-Integral and Stress-Intensity Factor at the Onset of Crack Extension

Keller, HP
Research engineer and division head, Deutsche Forschungs-und Versuchsanstalt für Luft-und Raumfahrt, Cologne,

Munz, D
Research engineer and division head, Deutsche Forschungs-und Versuchsanstalt für Luft-und Raumfahrt, Cologne,

Pages: 15    Published: Jan 1977

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Abstract

For a nickel-chromium-molybdenum steel and the aluminum alloy 7475, linear-elastic fracture mechanics can be applied to determine the stress-intensity factor at the onset of crack extension K^Io for specimens with (W − a)^c>0.4 (K^Io/σ^y)². For smaller specimens, K^Io can be calculated from the J-integral J^Io at the onset of crack extension, whereas linear-elastic fracture mechanics yield values which are too low. Below a minimum thickness B ≤ 50 J^Io/σ^y an increase of J^o was observed.