Fatigue Gauge Utilizing Slip Deformation of Alumium Foil : 1st Report, Slip Initiation and Surface Roughening Phenomena Under Uniaxial Stressing

Abstract

Fundamental characteristic of slip initiation and surface roughening phenomena in aluminum foil during the fatigue process are investigated under constant amplitude stressing. Applicability of the foil to the fatigue gauge that utilizes these phenomena to detect fatigue damage is discussed. It is found that the slip initiation phenomenon in aluminum foil is easily observed by an optical microscope and that the effects of temperature and cyclic speed on the slip initiation are quite small. Accordingly, aluminum foil can be used as the fatigue gauge that utilizes the slip initiation phenomenon. It is also found that evolution of surface roughness caused by the slip deformation is dependent on cyclic stress and the number of cycles. Therefore, this phenomenon also enables use of the foil as the fatigue gauge that makes use of surface roughness. Measuring accuracy of stress by this foil is about 5 MPa, and in-process measurements of cyclic strains or fatigue damage can be practicable provided that non-contact surface roughness measurement is adopted.