Forming Limit Prediction of Multi-layered Metal-Polymer Sheet Using Enhanced Marciniak-Kuczynski Model with Non-associated Hill48 Plasticity

Formability evaluation of the laminated polymer-metal films is important for manufacturing the pouch type Li-ion battery cell. In this work, the Marciniak-Kuczynski (M-K) model was enhanced to predict the forming limit of the multi-layered films used for the battery pouch. A rate-dependent Swift hardening law and anisotropic Hill48 yield criterion under the non-associated flow rule were adopted to accurately describe the plastic deformation of each layer. By assuming the iso-strain condition and perfect bonding between layers for the simplicity of modeling, the M-K model was re-formulated with the unknown variables such as strain increment and strain ratios in the groove zone based upon the compatibility condition and force equilibrium. In order to experimentally verify the predictive accuracy of the developed model, the calculated forming limit curve (FLC) was compared with the experimental FLC of a three-layer AA5182-O/Polypropylene/AA5182-O (AA/PP/AA) sandwich sheet. The results demonstrate the high accuracy of the proposed enhanced M-K method. In addition, based on the established modeling framework, the effect of each layer and its thickness on the formability of the laminated film were investigated for a nylon/AA/PP sandwich film for the battery pouch.