Delamination in deformed polymer laminated sheet metals

Polymer laminated sheet metal (PLSM) is a layered material in which a thin polymer film is bonded to a sheet metal substrate by means of an adhesive layer. The PLSMs could potentially be used as the blank materials for forming applications such as sheet drawing and stamping. Due to the difference in formability of metallic and polymeric components in the PLSMs, deformation of these materials induces residual stress in the polymer adherend involving thin film and adhesive layer. The residual stress, consequently, may cause interfacial delamination of polymer adherend and hence limit forming applications of the PLSMs. This paper presents an experimental method based on shear punching of uniaxially deformed PLSMs for the assessment of interfacial delamination between metallic substrate and polymer adherend. The experimental results show that the interfacial delamination depends on the amount of deformation and type of the polymer adherend material. In addition, it is shown that the deformation-induced delamination at the interface between the polymer adherend and metallic substrate is a retardation process and can be characterized by the three-parameter Voigt rheological model. Beyond the capabilities of the experiment, the Voigt model can estimate the amount of pure elastic delamination, which occurs immediately upon load removal after deformation.