Abstract
Abstract
Determination of plastic strain ratio (r, also known as the Lankford coefficient) from texture data is one of the most widely used applications of crystal plasticity methods. Early attempts using Taylor theory and x-ray texture data already provided practically useful information of e.g. drawability of sheet metals. Developments in recent decades within both electron backscatter diffraction and computational mechanics have significantly improved the accuracy of these calculations. Predictions can now be made that compares relatively well with experiments making r-value predictions from texture data a routine method within material and process development. The current work reviews recent studies on plastic strain ratio determination by computational means for aluminium sheet metal, with the aim to assess the expected accuracy using modern crystal plasticity methods. Furthermore, we investigate the major sources of error in these calculations by comparison between previous studies and with new experiments and calculations. In particular, we observe and investigate a maximum in the absolute error occurring typically at 45° to the rolling direction. The sources of this error are discussed in terms of both model conditions and the material heterogeneities giving rise to anisotropy.