Detachment of a rigid solid from an elastic wavy surface: Experiments

• Published in: Journal of the mechanics and physics of solids Vol. 55; no. 3; pp. 473 - 488
• Main Authors: Guduru, P.R., Bull, C.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-03-2007
• Subjects: Adhesion; Contact instability; Contact mechanics; Interface strength; Wavy surface; Contact instability; Wavy surface; Adhesion; Interface strength; Contact mechanics
• ISSN: 0022-5096
• DOI: 10.1016/j.jmps.2006.09.007

The mechanics of detachment of a rigid solid from an elastic wavy surface has been analyzed in a recent article, in which the axisymmetric case of a sphere and the plane strain case of a cylinder were considered. Due to the qualitative similarities, the discussion was limited to the axisymmetric case only. It was shown that the surface waviness makes the detachment process proceed in alternating stable and unstable segments and each unstable jump dissipates mechanical energy. As a result, the external work and the peak force required to separate a wavy interface are higher than the corresponding values for a flat interface, i.e., waviness causes interface toughening as well as strengthening. In this paper, a systematic experimental investigation is presented which examines the above theoretical analysis, by measuring adhesion between a “rigid” wavy punch and a soft “elastic” material, which is a block of gelatin here. The observed increase in adhesion due to waviness closely agrees with the theoretical predictions within the experimental and material uncertainties. The experiments not only validate the theory, but also demonstrate that adhesion of a soft material can be substantially enhanced by topographic optimization alone, without modifying the surface chemistry.