Prediction of residual stresses in biaxial stretching of tailor welded blanks by finite element analysis

Abstract

Residual stresses in sheet metal components play an important role in determining the life of parts especially in automotive industry. In this work, residual stresses have been predicted numerically in biaxial stretching of laser welded interstitial free (IF) steel blanks of different thickness combinations. The effective stress-effective strain curves of the parent sheets obtained from uniaxial tensile tests have been used as an input in finite element (FE) simulations to define the flow behavior of the materials. It has been found out that the residual stresses are tensile and similar on both sides of the weld zone in tailor welded blanks (TWB) of same thickness combination. In TWBs of different thickness combinations, the residual stresses on both sides are tensile and almost equal in the central region of the cup and they became compressive as the distance from the pole increases. The effect of thickness ratio on residual stresses has also been predicted in FE simulations of biaxial stretching of TWBs. It has been found out that with increase in the thickness ratio, the residual stress has slightly increased. Residual stresses have also been determined experimentally by using x-ray diffraction technique and it has been found out that the predicted values agreed well with the experimental results.