Fatigue crack growth and threshold measurements at very high frequencies

Abstract

Fatigue testing at ultrasonic frequencies makes it possible to investigate the fatigue properties of materials in an effective and time saving manner. The mechanical and electrical components of ultrasound equipment are described in detail. Different testing and evaluation procedures are reviewed. Recommendations on how to perform high frequency fracture mechanics studies and to evaluate experimental results are described. Recent developments for multiaxial loading, for performing in-service loading fatigue experiments, and for realising high frequency torsional vibrations are described. A survey of fatigue investigations of metallic materials, composites, metallic glass, and ceramics, determined with the ultrasound method, is presented. Intrinsic frequency effects are reviewed, emphasising the influences on dislocation structures, crack initiation, and fatigue crack growth for pure metals and for technical materials. The advantages and disadvantages of the ultrasound method are compared with those of conventional fatigue testing equipment.