Experimental and numerical investigations of springback and residual stresses in bending of a three-ply clad sheet

In the present work, springback behaviour of a three-ply clad sheet metal, comprising of layers of SS430 and SS304 sandwiched with a layer of AA1050 is investigated in V-bending by using analytical, experimental and simulation techniques. The developed analytical model is based on theory of bending using Hill's anisotropic yield criterion. The tensile properties of the clad sheet and individual layers oriented at three different directions w.r.t. the rolling direction are characterized. The tensile properties of the individual layers are used in the material model of analytical and numerical predictions of the springback. It is observed that the samples of the clad sheet which are transverse to the rolling direction, exhibit highest springback values due to higher tensile strength of the sheet when compared with the results acquired for other two orientations w.r.t. the rolling direction. These results are endorsed by the springback results obtained from analytical and simulation methods. The effect of sheet setting on the die during bending is also investigated using different techniques. The resulting longitudinal stresses before and after springback are analysed on inner and outer layers of the tested samples using experimental and numerical simulation procedures. In both the cases of sheet settings, the results of residual stress after springback predicted by simulations agree with the experimental results except a few cases.