Electroadhesive sphere-flat contact problem: A comparison between DMT and full iterative finite element solutions

The electroadhesive contact between a conductive sphere with a rigid substrate, both coated with an electrically insulating layer is studied, by adopting two solution strategies: (i) a DMT approximation and (ii) an iterative finite element model which accounts for the effect of the electroadhesive tractions on the deformation of the elastic solids. The contact problem is solved by varying the applied voltage and the elastic modulus of the coating layer. The two approaches (i) and (ii) give comparable results only in the limit of very low applied voltage, while they differ quantitatively and qualitatively at high voltage, as the DMT approach largely fails in predicting the repulsive contact force, which leads to greatly overestimate the macroscopic adhesive force.