THE FORMATION OF SLIP BANDS IN ALUMINUM FOIL SUBJECT TO VARIABLE STRESS LOADING AND THE APPLICATION OF THIS TECHNIQUE TO STRESS MEASUREMENT

In this paper, the fundamental characteristics of fatigue slip bands f ormed in an aluminium foil are investigated under both constant and va riable stresses, and this phenomenon is utilized to monitor the stress amplitude with the use of the foil. It is found that variation of str ess amplitude hardly affects the increase of slip bands, and the fract ion of slip bands under variable stress is correlated with the equival ent stress defined by (SIGMAsigma(i)(alpha)N(i)/SIGMAN(i))1/alpha, whe re sigma(i), N(i) and alpha are stress amplitude, the number of cycles and the material factor which is peculiar to the foil used, respectiv ely. It is concluded that the fraction of slip bands can be a measure of stress evaluation for both constant and variable stresses.