Analysis of the axisymmetric frictionless adhesive contact between a spherical conducting indenter and an FGPM layer using a Maugis model

As component size decrease to microscopic and nanoscopic scales, the adhesive effect becomes more important. In this study, the axisymmetric frictionless contact problem, which included adhesion, between the functionally graded piezoelectric materials (FGPM) layered half-space and a spherical conducting indenter was investigated. The electromechanical properties of the FGPM layer varied exponentially in the thickness direction. According to a Maugis-type adhesion theory, the problem could be reduced to a set of Cauchy singular integral equations of the first kind using the Hankel integral transform technique. Numerical calculations were conducted to determine the effects of the actual Maugis adhesion parameters (the adhesive stress, the work of adhesion, the gradient index, the indenter radius, and the substrate material) on the pull-off force, the contact stress, the in-plane stress, the electrical charge distribution, the contact region, the adhesive region, the indentation depth, and the electrical potential. Our research reveals that the pull-off force increased with the adhesive stress, the work of adhesion, the indenter radius, and decreased with the gradient index. The absolute value of the indentation depth and the electrical potential at the pull-off moment increased with the adhesive stress, the work of adhesion, the indenter radius, and decreased with the gradient index. As the gradient index increased, the surface compressive normal stress at the center of the contact area and the surface electrical charge distribution at the contact central and edge areas also increased. The results show that the electromechanical contact performance of the FGPM layer can be optimized by adjusting the actual Maugis adhesion parameters, enabling modification of smart structure characteristics.