In this work the effect of substrate roughness on the adhesion of gecko foot-hair like nano structures as opposed to solid elastic materials is described and models of both synthetic nano-hairs and hair-substrate interaction are developed. First, by combining linear beam theory and geometric constraints, a nonlinear elastic model for the hair is derived. Then it is shown how for a given random ...

In this paper, the classical JKR theory of the adhesive contact of isotropic elastic spheres is extended to consider the effect of anisotropic elasticity. The contact area will then generally be non-circular, but in many cases it can reasonably be approximated by an ellipse whose dimensions are determined by imposing the energy release rate criterion at the ends of the major and minor axes. Ana...

Gecko and many insects have adopted nanoscale fibrillar structures on their feet as adhesion devices. Here, we consider adhesion between a single fiber and a substrate by van der Waals or electrostatic interactions. For a given contact area A, the theoretical pull-off force of the fiber is sigma(th)A where sigma(th) is the theoretical strength of adhesion. We show that it is possible to design ...

The rupture forces of individual host-guest complexes between beta-cyclodextrin (beta-CD) heptathioether monolayers on Au(111) and several surface-confined guests were measured in aqueous medium by single molecule force spectroscopy using an atomic force microscope. Anilyl, toluidyl, tert-butylphenyl, and adamantylthiols (0.2-1%) were immobilized in mixed monolayers with 2-mercaptoethanol on go...

The design of released microstructures depends on accurate knowledge of residual stresses and associated elastic constants. The MIT-developed material test procedure, M-Test, uses the variation of pull-in voltage with beam length to extract residual stress and elastic modulus from in-situ test structures. This thesis reports a fully automated computer-microvision procedure that automatically de...

Joint lockup due to dowel misalignment significantly affects joint and concrete pavement performance by causing distresses. The current paper presents an experimental study assess the effectiveness of standard pull-out test in evaluation effect on Jointed Plain Concrete Pavement (JPCP). tests were conducted at two different ages ; 3 28 days. results showed that or individually pulling misaligne...

Fiber shedding is a critical problem in biomedical textile debridement materials, which leads to infection and impairs wound healing. In this work, single fiber pull-out test was proposed as an in vitro evaluation for the fiber shedding property of a textile pile debridement material. Samples with different structural design (pile densities, numbers of ground yarns and coating times) were prepa...