Quantification of roping intensity on aluminium sheets by Areal Power Spectral Density analysis

To quantify the roping level on strained AA6xxx sheets, a new automatic procedure is introduced and applied. The method calculates the Areal Power Spectral Density (APSD) from digitized surface images and determines the separate contributions of isotropic and unidirectional components using their spatial dimensions. To deal with mixed roughness morphologies, the overall roping grade is given by the ratio of these two individual contributions. lysis of the surface appearance of 16 different samples of AA6016 shows that the roping grade is in good agreement with the three groups of roping level (Low, Intermediate and High) determined previously by visual judgment. The procedure appears robust and versatile if some data constraints are respected.