STP711: KId-Values Deduced from Shear Force Measurements on Double Cantilever Beam Specimens

    Chow, C-L
    Research assistant and professor, University of RochesterDe Havilland Aucraft of Canada, Ltd., RochesterDownsview, N.Y.Ont.

    Burns, SJ
    Research assistant and professor, University of RochesterDe Havilland Aucraft of Canada, Ltd., RochesterDownsview, N.Y.Ont.

    Pages: 12    Published: Jan 1980


    Abstract

    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.

    Keywords:

    cantilever beams, crack propagation, fracture properties, critical stress intensity, crack velocity


    Paper ID: STP27450S

    Committee/Subcommittee: E08.03

    DOI: 10.1520/STP27450S


    CrossRef ASTM International is a member of CrossRef.