Deformation mechanism and failure-tolerant characteristics of polymer-coated sheet metal laminates subjected to different loading conditions

The mechanical performance of polymer-coated sheet metal laminates (PSML) is greatly affected by loading conditions. However, under more complex loads, the understanding of their deformation behaviors remains limited. This research aims to investigate the deformation mechanism and failure-tolerant characteristics of a new type of PSML with weak adhesion when subjected to the quasi-static perforation and more complex dynamic incremental deformation loads. The effects of factors such as layer arrangements, tool nose sizes, interfacial bonding, and mechanical properties of each layer on mechanical performance of the PSML system are analyzed through analytical and/or experimental approaches for different loading conditions. For quasi-static penetration loading, if the polymer layer faces the tool, failure in the metal (AA) layer could be delayed, especially when a larger tool is applied, which outperforms the case of metal layer facing the tool. Moreover, the developed analytical model can predict the variation trends of perforation energy correctly. Under dynamic incremental deformation loads, failure modes include one-layer fracture, two-layer fracture, delamination, and their mixed case. Besides, it is worth emphasizing that layer arrangement is the most dominating factor affecting deformation behaviors. Unlike the case of metal layer facing the tool, the PA layers facing the tool that have low stiffness in the weak adhesion condition can facilitate the synergistic deformation mechanism of PSML as a whole material. Our findings indicate that applying PA coatings to metal plate with weak bonding may provide a practical solution to improving the mechanical performance of existing metallic materials.