SYMPOSIA PAPER Published: 01 January 1986

Minimum Time Criterion for Crack Instability in Structural Materials


Cracks in 4340 steel, 1018 steel, and 6061 aluminum specimens were loaded by short pulses of various amplitudes and durations of about 20 to 80 μs to generate experimental results of critical stress amplitudes for crack instability. Stress intensity histories experienced by the cracks at instability were calculated by a finite element method. The results showed that it is necessary to introduce time effect into the instability criterion, such as in the minimum time theory proposed by one of the authors. Correlation between the minimum times obtained for the three materials and their mechanical properties was discussed to clarify the physical meaning of the minimum time. The experimental results showed that the minimum time becomes long for the ductile material.

Author Information

Homma, H
Toyohashi University of Technology, Toyohashi, Japan
Shockey, DA
SRI International, Menlo Park, CA
Hada, S
Toyohashi University of Technology, Toyohashi, Japan
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Developed by Committee: E08
Pages: 683–696
DOI: 10.1520/STP17423S
ISBN-EB: 978-0-8031-4972-4
ISBN-13: 978-0-8031-0472-3