FATIGUE GAUGE UTILIZING SURFACE ROUGHENING OF ALUMINUM FOIL

The surface roughening phenomenon of an aluminum foil is utilized as t he measure of stress measurements under variable amplitude stressing a nd fundamental characteristics of the evolution of the roughness are i nvestigated. The effect of load history on the surface roughening does not appear when the stress amplitude varies many times. Under such a loading condition, the average stress amplitude is measured from the s urface roughness of the foil, and this is defined by (SIGMAsigma(i)(al pha)N(i)/SIGMAN(i)(l/alpha), where sigma(i), N(i) and alpha are the st ress amplitude, the number of stress cycles of sigma(i), and the mater ial factor, respectively.