Adhesion of a cylindrical punch with elastic properties that vary radially

The adhesion of a rigid substrate and an adhered straight cylindrical punch with a non-homogeneous elastic modulus is analyzed. The stress distributions are obtained along the interface for various elastic modulus gradients. The calculations are performed in the commercial finite element software Abaqus using a user material (UMAT) subroutine to control the dependence of Young’s modulus on the radial position. The UMAT code is shared in the paper. The results reveal that the decreasing elastic modulus toward the perimeter of the punch can be used to significantly reduce the normal stress magnitudes in the singularity domain, which leads to stronger adhesion. The increase in the adhesion strength is characterized numerically. The effect of Poisson’s ratio is also analyzed.