EXPERIMENTAL AND NUMERICAL STUDIES ON SPRING BACK IN U-BENDING OF TAILOR WELDED BLANKS

Abstract

Tailor welded blank (TWB) is an advancement in the field of sheet metal forming in which multiple blanks are welded together to create a single blank prior to forming process. Springback behaviour of TWBs in bending is complex due to thickness, material combination and rolling direction of sheet metal which shows variation with different Punch corner radius. In this Thesis, the effect of punch profile radius on the springback of Parallel to length welded strips has been investigated in U-bending operation with Tool bend angle of 90° and using punches with three different punch profile radii of 7.5 mm, 10 mm and 12.5 mm. TWBs were prepared by laser welding of interstitial- free steel blanks with a thickness combination of 0.8 mm and 1.5 mm. The Tensile properties of parent materials and tailored blanks were evaluated by Tension test as per ASTM-E8M standard. The bend samples with transverse weld line were prepared to a size of 20mmX130mm to ensure plane strain bending. The different naked eye observations of tailoring Pattern with one sheet to other sheet lead to modelling of TWBs Cross-section. After Proper modelling Finite element (FE) simulations were performed for TWBs Model with and without Weldline property. Whereas in with Weldline property as per Width provided by ASTM-E8 for subsized and micro specimens used for simulation using Abaqus. All FEA Specimens in Abaqus are divided on the basis of material orientation and section assignment for Centre line TWBs cross-section Integration model, for top surface shell element analysis, with anisotropy and without anisotropy were found to be in good agreement with the experimental results.