Fatigue Gage Utilizing Surface Roughening of Aluminum Foil

Abstract

The surface roughening phenomenon of an aluminum foil is utilized as the measure of stress measurements under variable amplitude stressing and fundamental characteristics of the evolution of the roughness are investigated. 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 surface roughness of the foil, and this is defined by (∑σiαNi/∑Ni)1/α, where σi , Ni and α are the stress amplitude, the number of stress cycles of σi , and the material factor, respectively.