Abstract
The evolution of surface roughness of aluminum foil caused by fatigue slip deformation is dependent on cyclic stress and the number of cycles. In order to use aluminum foil as a fatigue gauge by utilizing its surface roughness, isoroughness curves are obtained and an empirical formula for them is proposed. The effect of material factors, i.e., grain size and thickness of the foil, on the evolution of roughness is also investigated. It is found that an increase in roughness is well represented by Ra=(σα/2/kO)N1/2+m, where α, kO and m are material constants. Accordingly, if the number of cycles N and the center line average height Ra are measured, the applied stress σ is evaluated by this formula. It is also found that the effect of the thickness on the roughness is remarkable, while the effect of the grain size is very small. This is beneficial to control the strain sensibility of the gauge without changing the gauge length.
