Controlling the adhesive pull-off force via the change of contact geometry

A first-order asymptotic analysis of the Griffith energy balance in the Johnson–Kendall–Roberts model of adhesive contact under non-symmetric perturbation of the contact geometry is presented. The pull-off force is evaluated in explicit form. A particular case of adhesive contact between a relatively stiff sphere and an elastic half-space is considered under the assumption that the sphere geometry is changed by the application of an arbitrary lateral normal surface loading. The effect of the sphere Poisson’s ratio on controlling the adhesive pull-off force is considered. This article is part of a discussion meeting issue ‘A cracking approach to inventing new tough materials: fracture stranger than friction’.

Energy Principle in Crack Propagation

Fracture mechanics is an engineering discipline, which originated from Griffith energy-balance concept. The energy method is the most powerful analytical tool for fracture mechanics. Starting from energy principle in crack propagation, quasi-static governing equations and energy release rate of DCB specimen can be derived by energy principle in this paper. Finally, some correlative problems are discussed.