Flexural Fatigue Machine for High Temperature Operation at Resonance in Vacuum

Abstract

A resonance type reversed bending, high temperature fatigue machine for operation at constant bending amplitude in vacuum has been developed. The vibration frequency is maintained at resonance by means of a feedback circuit employing a capacitance pickup. Another circuit maintains a constant amplitude of vibration. As fatigue cracks are developed, the resonant frequency decreases. Curves of resonant frequency versus time at 800°C for materials of high damping, such as type 316 stainless steel, and for materials of low damping, such as Inconel X, illustrate the development of fatigue damage.