Multispecimen Fatigue Crack Propagation Testing

Abstract

Chains of miniature center-cracked-tension specimens were tested on a conventional testing machine and on a prototypic in-reactor fatigue machine as part of the fusion reactor materials alloy development program. Annealed and 20 percent cold-worked 316 stainless steel specimens were cycled under various conditions of temperature, frequency, stress ratio and chain length. Crack growth rates determined from multispecimen visual measurements and from an electrical potential technique were consistent with those obtained by conventional test methods. Results demonstrate that multispecimen chain testing is a valid method of obtaining fatigue crack propagation information for alloy development.

Apparatus for Accelerating Measurements of Environmentally Assisted Fatigue Crack Growth at Low Frequency

“…Ermi et al 4 in 1981 proposed linking eight miniaturized center-cracked tension specimens and loading them cyclically in tension. The load was applied by cyclically pressurizing helium in a chamber via a bellows at the top of the chain of specimens.…”