SEDL / STP / STP877-EB / STP32887S

Krak-Gages for Automated Fatigue Crack Growth Rate Testing: A Review

Liaw, PK
Senior engineers and principal engineer, Westinghouse R&D Center, Pittsburgh, PA

Logsdon, WA
Senior engineers and principal engineer, Westinghouse R&D Center, Pittsburgh, PA

Roth, LD
Senior engineers and principal engineer, Westinghouse R&D Center, Pittsburgh, PA

Hartmann, H-R
President, Hartrun Corp., Chaska, MN

Pages: 20    Published: Jan 1985

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Abstract

Bondable Krak-gages were utilized to monitor fatigue crack growth rates (FCGR) of various steels in air and salt water at 24°C and in wet hydrogen at 80°C. The FCGR data generated via bondable Krak-gages were consistent with those generated via either the compliance technique or optical measurements. Moreover, Krak-gages were effective in monitoring short crack extension.

Using atomic fusion technology, Krak-gages were sputtered on specimens so as to perform high-temperature (288 and 427°C) FCGR experiments. The FCGR results obtained with the sputtered Krak-gages were in good agreement with those obtained by the compliance method.

The Krak-gages were found to be a valuable addition to fracture mechanics testing. They readily interface with computers for fully automated FCGR experiments.