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Description
In a deep drawing process, the friction at the sheet metal-die contact interface affects the material flow in the flange as well as in die entry radius region, affecting product quality significantly. The accuracy of predicted drawing force and thinning in deep drawing simulation strongly depends on friction modelling. The Coulomb’s friction model with a constant coefficient of friction is generally assumed in simulations. In reality, the actual friction coefficient depends on process variables such as local contact pressure, relative sliding velocity, and strain in the sheet material. In this work, an approach is presented for friction modelling in deep drawing simulations of dual phase (DP600) steel sheets. In order to account for variation in friction coefficient, the TriboForm plugin is used in combination with AutoForm software. The predicted friction coefficients are verified using the data from standard strip drawing friction tests under conditions similar to that exist in the flange area during deep drawing. The experimental and simulation results of the friction coefficient show a good overall agreement. Deep drawing simulations have been performed considering Coulomb’s model and Triboform friction model. The simulation results are validated using deep drawing experiments. It is concluded that the numerical prediction of the punch force, strain distribution and percentage thinning is highly sensitive to friction. In addition to an overall improvement of the predictive accuracy of deep drawing simulations by friction modelling, the effect of varying frictional conditions can be incorporated into deep drawing simulations using this approach.