Filters

2010 - 201912020 - 20211

More filters

2019 - 201912020 - 20211
Reset filters

Settings

Author: McMeeking, Robert × Version: publishedVersion ×

Search Results

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    Breakdown of continuum models for spherical probe adhesion tests on micropatterned surfaces
    (Amsterdam [u.a.] : Elsevier Science, 2021) Bettscheider, Simon; Yu, Dan; Foster, Kimberly; McMeeking, Robert; Arzt, Eduard; Hensel, René; Booth, Jamie A.
    The adhesion of fibrillar dry adhesives, mimicking nature's principles of contact splitting, is commonly characterized by using axisymmetric probes having either a flat punch or spherical geometry. When using spherical probes, the adhesive pull-off force measured depends strongly on the compressive preload applied when making contact and on the geometry of the probe. Together, these effects complicate comparisons of the adhesive performance of micropatterned surfaces measured in different experiments. In this work we explore these issues, extending previous theoretical treatments of this problem by considering a fully compliant backing layer with an array of discrete elastic fibrils on its surface. We compare the results of the semi-analytical model presented to existing continuum theories, particularly with respect to determining a measurement system- and procedure-independent metric for the local adhesive strength of the fibrils from the global pull-off force. It is found that the discrete nature of the interface plays a dominant role across a broad range of relevant system parameters. Accordingly, a convenient tool for simulation of a discrete array is provided. An experimental procedure is recommended for use in conjunction with this tool in order to extract a value for the local adhesive strength of the fibrils, which is independent of the other system properties (probe radius, backing layer thickness, and preload) and thus is suitable for comparison across experimental studies.
  • Thumbnail Image
    Item
    The role of the backing layer in the mechanical properties of micrometer-scale fibrillar structures
    (Saarbrücken : Leibniz-Institut für Neue Materialien, 2010) Guidoni, Griselda; Schillo, Dominik; Hangen, Ude; Castellanos, Graciela; Arzt, Eduard; McMeeking, Robert; Bennewitz, Roland
    The contact mechanics of a micro-fabricated fibrillar surface structure made of poly(dimethylsiloxane) (PDMS) was studied in this work. The attachment and detachment of individual fibrils to and from a spherical indenter upon approach and retraction are detected as jumps in force and stiffness. A quantitative model describes the jumps in stiffness values by taking into account the deformation of the backing layer. The results emphasize the importance of long-range interactions in the contact mechanics of elastic materials and confirm the concepts underlying the development of fibrillar adhesive materials.