One-step FEM based control of weld line movement for tailor-welded blanks forming

One-step finite element method (also called inverse approach) is widely used recently in the automobile industry. In order to speed up and ensure the convergence of Newton–Raphson iterations, energy based 3D mesh mapping algorithm is used to obtain the initial solution. The action of punch and die, effect of restraining forces under the blankholder due to drawbeads and blankholder pressure with friction are considered as well. Hydraulic controlled pads used to clamp the weld line during deep drawing process are simplified as static external force to reduce the movement of weld line. The above-mentioned methods have been implemented in authors’ in-house one-step code InverStamp. The initial weld line can be well predicted by one-step finite element analysis from the desired weld line in a formed workpiece which is demonstrated by a rectangular cup drawing study.