SEDL / STP / STP877-EB / STP32889S

An Automated Fatigue Crack Growth Rate Test System

Cheng, Y-W
Metallurgist and physicist, Fracture and Deformation Division, National Bureau of Standards, Boulder, CO

Read, DT
Metallurgist and physicist, Fracture and Deformation Division, National Bureau of Standards, Boulder, CO

Pages: 11    Published: Jan 1985

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Abstract

An automated fatigue crack growth rate (FCGR) test system has been developed that can be used for tests of constant-load-amplitude FCGR above 10⁻⁸ m/cycle [ASTM Test Method for Constant-Load-Amplitude Fatigue Crack Growth Rates Above 10⁻⁸ m/Cycle (E 647-83)] at normal (∼ 10 Hz) or low (∼ 0.1 Hz) cyclic frequencies and for tests of near-threshold and variable-load-amplitude FCGR. The test system consists of a minicomputer, a programmable arbitrary waveform generator, a servo-hydraulic test frame, and a programmable digital oscilloscope. The crack length is measured using the compliance technique; the FCGR and the stress-intensity factor range are calculated and plotted automatically during the test.