SYMPOSIA PAPER Published: 01 January 1980
STP27450S

-Values Deduced from Shear Force Measurements on Double Cantilever Beam Specimens

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Time-varying shear force measuring techniques have been used to investigate the dynamic critical stress-intensity factor versus crack propagation velocity curve. The product of the shear force at the loading end times the square root of the loading time on a rapidly wedged double cantilever beam specimen is uniquely related to the critical bending moment at the crack tip. Static compliance measurements on side-grooved specimens were incorporated into a Bernoulli-Euler beam model for calibration purposes and to eliminate the inappropriate built-in beam assumption. The compliance calibration shows a crack length shift from a measured crack length to a beam model length at a fixed compliance value. This shift does not affect the magnitude of the calculated critical bending moment at the crack tip when the load and the load-point displacement are measured quantities. The effective crack length is calculated from the beam model length with the length shift correction. The KId-values (calculated from the critical bending moment) versus crack velocity have been investigated at several test temperatures for a low-carbon steel. KId-values show a generally decreasing trend when crack velocity increases. KIc at fast fracture initiation is larger than the corresponding KId-value for all tests recorded.

Author Information

Chow, C-L
De Havilland Aucraft of Canada, Ltd., Downsview, Ont., Canada
Burns, SJ
De Havilland Aucraft of Canada, Ltd., Downsview, Ont., Canada
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Details
Developed by Committee: E08
Pages: 228–239
DOI: 10.1520/STP27450S
ISBN-EB: 978-0-8031-4779-9
ISBN-13: 978-0-8031-0317-7