Fatigue Apparatus for Extreme High Vacuum

Abstract

A constant amplitude, reverse bend stress fatigue testing device is described which permits simultaneous testing of up to eight specimens at extremely low pressure levels below 10⁻¹⁰ Torr. The vibratory force was provided by an electromagnetic exciter with vibration frequencies in the range of 50–200 cps. Fatigue tests with 1100‐H14 aluminum showed that a substantial increase in the cyclic fracture life was obtained in high vacuum as compared to the fatigue behavior in unit atmosphere of air. The fatigue life improvement increased proportionally with the cyclic stress frequency.