Creep plastic effects in sheet bending

Abstract

Creep-plastic effects in sheet bending are discussed as a transition phenomenon without making a number of ad hoc assumptions like a yield condition and a creep strain law. It is found that creep transition occurs in the extension region and takes place through the second stress-invariant, which is commonly used for determining the yield surface. The contraction region undergoes an elastic-plastic deformation. The analysis also gives the boundary separating the two regions.