Viscoelastic-adhesive contact modeling: Application to the characterization of the viscoelastic behavior of materials

In contacts involving viscoelastic materials, both the time-dependent modulus of the material and the adhesive interaction between contact surfaces play important roles. This work aims to derive viscoelastic-adhesive contact models for realistic contact analyses and develop a model-based-empirical method to determine localized properties (such as the time dependent creep compliance function) of a viscoelastic material considering surface adhesion and utilizing data from contact creep tests. The reported work is based on the viscoelastic fracture mechanics theory by Schapery (Schapery, 1989) and elastic contact mechanics models (Maugis, 1992; Johnson et al., 1971; Derjaguin et al., 1975). The Particle Swarm Optimization method (Kennedy and Eberhart, 1995) is utilized to find solutions to the nonlinear equations of this model. Contact creep tests of PDMS samples were designed and performed to validate the model. A multiple-decade power-law creep compliance function was obtained for a group of PDMS samples. The results show that the obtained creep compliance is a function of crosslink density of PDMS, independent of indenter tip size and the applied load. (C) 2013 Elsevier Ltd. All rights reserved.