Optimal Load Sharing in Bioinspired Fibrillar Adhesives: Asymptotic Solution

Abstract

We propose here an asymptotic solution defining the optimal compliance distribution for a fibrillar adhesive to obtain maximum theoretical strength. This condition corresponds to that of equal load sharing (ELS) among fibrils, i.e. all the fibrils are carrying the same load at detachment, hence they all detach simultaneously. We model the array of fibrils as a continuum of linear elastic material that cannot laterally transmit load (analogous to a Winkler soil). Ultimately, we obtain the continuum distribution of fibril's compliance in closed-form solution and compare it with previously obtained data for a discrete model for fibrillar adhesives. The results show improving accuracy for an incremental number of fibrils and smaller center-to-center spacing. Surprisingly, the approximation introduced by the asymptotic model show reduced sensitivity of the adhesive strength with respect to misalignment and improved adhesive strength for large misalignment angles.

Interface Stress Uniformity Design of Elastomer Adhesives

“…In a general linear system, the energy approach may suggest a scaling relation for the pull-off force as ‫ܨ‬ ∝ ඥܹ ୟୢ ‫ܣ‬ ‫ܥ‬ ⁄ , which has been widely applied in experimental research [2,3,11,17], where W ad is the work of adhesion, A is the interfacial area of adhesion, and ‫ܥ‬ = ∆ ‫ܨ‬ ⁄ ∝ ‫ݐ‬ ‫)ܧܣ(‬ ⁄ is the system compliance. Material compliance can also be adjusted to uniform the interface stress [7,12,17,18]. Combining interface stress uniformity and higher array packing ratio is expected to maximize the pull-off force.…”