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In this paper, the factors that affect the accuracy of springback prediction are discussed. Springback predictions of aluminum and high strength steel panels are compared with measurement data. The effect of springback can be reduced or eliminated through process control and die face compensation. The first method involves finding the root causes of springback and eliminating them through process modification. The second method is a direct way to eliminate the springback effect. For large springback with twisting, an incremental compensation is required and the final deviation can be controlled by setting tight convergent tolerance. Stamping production environment can introduce many variables which deviate from engineering condition. The paper shows that material property change within the same grade will cause significant springback variation. This means that the process control is one of the key factors that we have to pay attention to solve springback issue.

Springback is a major concern in stamping of advanced high strength steels (AHSS). The existing computer simulation technology has difficulty predicting this phenomenon accurately even though it is well developed for formability simulations. Great efforts made in recent years to improve springback predictions have achieved noticeable progress in the computational capability and accuracy. In this work, springback simulation studies are conducted using FEA software LS-DYNA®. Various parametric sensitivity studies are carried out and key variables affecting the springback prediction accuracy are identified. Recently developed simulation technologies in LS-DYNA® are implemented including dynamic effect minimization, smooth tool contact and newly developed nonlinear isotropic/kinematic hardening material models. Case studies on lab-scale and full-scale industrial parts are provided and the predicted springback results are compared to the experimental data.

The analysis of localized necking is strongly dependent on the yield function. Numerous yield criteria have been advanced to characterize the plastic deformation of sheet materials. Among them Hill's 1948 and the fourth form of 1979 yield criteria are the most commonly used yield criterion. A new and user-friendly yield criterion was proposed by Hill in 1993, which uses five independent and easily-obtainable material parameters. The present investigation compares these three yield criteria in forming limit predictions based on the M-K approach. The M-K analysis based on Hill's 1993 yield criterion yields forming limit predictions for aluminum in good agreement with experimental data. All three yield criteria are found to provide acceptable predictions for aluminum killed steel.