Understanding the mechanical properties of bionanofilms is important in terms of identifying their durability. The primary focus of this study is to examine the effect of water vapor annealed silk fibroin on the indentation modulus and hardness of graphene oxide-silk fibroin (GO-SF) bionanofilms through nanoindentation experiments and finite element analysis (FEA). The GO-SF bionanofilms were fabricated using the layer-by-layer technique. The water vapor annealing process was employed to enhance the interfacial properties between the GO and SF layers, and the mechanical properties of the GO-SF bionanofilms were found to be affected by this process. By employing water vapor annealing, the indentation modulus and hardness of the GO-SF bionanofilms can be improved. Furthermore, the FEA models of the GO-SF bionanofilms were developed to simulate the details of the mechanical behaviors of the GO-SF bionanofilms. The difference in the stress and strain distribution inside the GO-SF bionanofilms before and after annealing was analyzed. In addition, the load-displacement curves that were obtained by the developed FEA model conformed well with the results from the nanoindentation tests. In summary, this study presents the mechanism of improving the indentation modulus and hardness of the GO-SF bionanofilms through the water vapor annealing process, which is established with the FEA simulation models.

Understanding mechanical behaviors influenced by electric potential and tribological contacts is important for verifying the robustness and reliability of applications based on metallic porous nanostructures in electrical stimulations. In this work, nickel-based metallic porous nanostructures were studied to characterize their mechanical properties and morphologically dependent contact areas during application of an electric potential using a nanoindenter. We observed that the indentation moduli of nickel-based metallic porous nanostructures were altered by pore size and application of electric potential. In addition, the structural aspects of the surface morphology of nickel-based porous nanostructures had a critical effect on the determination of contact area. We suggest that the relation between electric potential and the mechanical behaviors of metallic porous nanostructures can be crucial for building mechanically robust functional devices, which are influenced by electric potential. The morphological shape characteristics of metallic porous nanostructures can be alternative decisive factors for manipulation of tribological performance through regulation of contact area.