CNT-polymer nanocomposites under frictional contact conditions

The unique intrinsic physical properties of Carbon NanoTubes (CNTs) suggest that they are ideal fillers for high-performance composites. Although some experimental studies have revealed the potential of these nanoparticles to tailor the tribological properties of polymer-based composites, the number of theoretical studies on the characterization of their frictional behavior is still very low. This paper is aimed at filling this lacuna by addressing the theoretical analysis of the indentation response of CNT-polymer nanocomposites. To do so, it is first necessary to compute the overall mechanical properties of CNT-polymer composites. Secondly, these properties must be used to evaluate the macroscopic indentation response of the composites. In this work, an extended Mori-Tanaka approach is used to extract the constitutive properties of CNT-polymer nanocomposites. On the basis of ad hoc Eshelby's tensors accounting for particular wavy filler geometries, along with a two-parameter agglomeration model, the homogenization process is performed considering the coupled effect of fillers' waviness and agglomeration. Afterward, a 3D boundary element formulation for contact modeling is applied to study the indentation response of these nanocomposites. The main objective of this paper focuses on analysing the influence of micromechanical features such as fiber content, orientation, waviness, and dispersion on the indentation response of CNT-polymer nanocomposites. Detailed parametric analyses are presented to characterize this phenomenon under frictional contact conditions. The numerical results demonstrate that fillers' waviness and agglomeration have a coupled detrimental effect on the macroscopic response of CNT-reinforced composites.