SYMPOSIA PAPER Published: 01 January 1990

Direct Curve Analysis: A Guide to the Methodology


A direct method for evaluating J-R curves from load displacement data is proposed. This method eliminates a need for automatic crack length monitoring equipment. The method uses the geometric normalization suggested by Ernst for deeply cracked bend specimens to develop calibration curves which relate load, displacement, and crack length. Given two of these parameters, the third can be determined from the calibration curves. These curves are developed by assuming a functional form with unknown constants and evaluating the unknowns at calibration points in the test. This method was previously proposed using a power law functional form. In this paper a more general functional form is proposed which combines a power law and straight line. The method is studied for a variety of materials and specimen sizes. From the results a recommendation is made on how to generally apply the method.

Author Information

Herrera, R
National University of Mar Del Plata, Mar Del Plata, Argentina
Landes, JD
The University of Tennessee, Knoxville, TN
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Developed by Committee: E08
Pages: 24–43
DOI: 10.1520/STP18987S
ISBN-EB: 978-0-8031-5134-5
ISBN-13: 978-0-8031-1299-5