SYMPOSIA PAPER Published: 01 January 1989

Automated Fatigue Crack Growth Monitoring: Comparison of Different Crack-Following Techniques


A software has been developed to conduct constant amplitude fatigue crack growth tests on the lines of a standard test method proposed by the American Society for Testing and Materials (ASTM E 647).

In this paper, after a brief description of this software, the results of calibration tests conducted using compact tension specimens of the high-strength aluminum alloy 2024-T351 are presented and discussed.

The crack length was monitored by the compliance technique and the d-c potential drop technique for automated tests and by optical means for manual verification.

Analysis of the results shows that both crack-following techniques are suitable for automated crack growth monitoring. The maximum absolute error for the compliance technique is on the order of 2.5% and on the order of 1.3% for the potential drop technique.

Calibration functions relating the crack length to normalized compliance for measurements under the loading axis and to the potential drop have been determined for the studied specimen geometry.

Finally, the experimental results relating the crack growth rate to the amplitude of the stress intensity factor by the different techniques used are compared.

Author Information

Ranganathan, N
E.N.S.M.A., Poitiers, France
Guilbon, G
E.N.S.M.A., Poitiers, France
Jendoubi, K
E.N.S.M.A., Poitiers, France
Nadeau, A
E.N.S.M.A., Poitiers, France
Petit, J
E.N.S.M.A., Poitiers, France
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Developed by Committee: E08
Pages: 77–92
DOI: 10.1520/STP24014S
ISBN-EB: 978-0-8031-5086-7
ISBN-13: 978-0-8031-1251-3