Effect of Friction Modelling on Damage Prediction in Deep Drawing Simulations of Rotationally Symmetric Cups

Abstract

The damage state in a formed component has a significant influence on the performance of the component in service. Controlling damage evolution during forming through specific modifications of the process parameters will therefore allow an improvement of this performance. The evolution of the stress-strain state during the forming process is the primary influencing factor of the resulting damage state. The stress-strain state is influenced by the friction between tools and workpiece. To investigate the cause-effect relationship between friction and damage evolution in the deep drawing process, Finite Element simulations of the deep drawing of rotationally symmetric cups were performed. Punch velocity and blank holder force were varied. Damage was predicted using a Lemaitre damage model. The damage states predicted using a Coulomb friction law and a model incorporating a dependence on contact normal stress and relative velocity were compared. The parameter-dependent friction model predicted a change in the damage distribution after forming when varying the process parameters, which was not found using the Coulomb friction law.

Influence of process parameters and process set-up on damage evolution during stretch drawing of u-shaped profiles

“…The model parameters of the calibrated material model are consistent with prior work [8]. The constitutive model was implemented as a VUMAT subroutine and was successfully used and validated in earlier work [13,14].…”

Numerical Prediction of the Influence of Process Parameters and Process Set-Up on Damage Evolution during Deep Drawing of Rectangular Cups

“…Similar to this, Barrera et al calibrated the anisotropic Hosford-Coulomb ductile fracture criterion to foresee the fracture initiation during the Erichsen test of DC04EK4 drawing steel [28], while Saxena et al used the Lemaitre damage model for prediction of fracture initiation in deep drawn of rectangular cups [29]. Considering the microscopic scale of damage and the definition of damage that underlies this work, Nick et al investigated in previous work the influence of friction modeling on damage prediction in deep drawing simulations of rotationally symmetric cups of DP800 dual phase steel [30], as well as the damage evolution during Nakajima tests [31] and during single-step, two-step, und reverse deep drawing of rotationally symmetric cups from DP800 dual phase steel [32].…”

“…The work is a continuation of refs. [30][31][32] and used the simulation models established therein. However, the significantly more complex stress state in the component due to its shape results in a different challenge.…”

“…The model parameters of the calibrated material model are identical to previous work and were published in ref. [30]. The constitutive model was implemented as a Vumat subroutine and has already been successfully used in previous work [30,32].…”

“…[30]. The constitutive model was implemented as a Vumat subroutine and has already been successfully used in previous work [30,32].…”