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Adhesively bonded elastic layers with thicknesses that are small relative to their lateral dimensions are used in a wide variety of applications. The mechanical response of the compliant layer when a normal stress is imposed across its thickness is determined by the effects of lateral constraints, which are characterized by the ratio of the lateral dimensions of the layer to its thickness. From this degree of confinement and from the material properties of the compliant layer, we predict three distinct deformation modes: ͑1͒ edge crack propagation, ͑2͒ internal crack propagation, and ͑3͒ cavitation. The conditions conductive for each mode are presented in the form of a deformation map developed from fracture mechanics and bulk instability criteria. We use experimental data from elastic and viscoelastic materials to illustrate the predictions of this deformation map. We also discuss the evolution of the deformation to large strains, where nonlinear effects such as fibrillation and yielding dominate the failure process.

The effects of molecular weight and acrylic acid content on the adhesive properties of a series of monodisperse poly(n-butyl acrylate) materials have been investigated. The short-time adhesion, or “tackiness”, of these model pressure-sensitive adhesives was quantified by performing probe-tack experiments. These experiments consist of a bonding phase, where a flat punch is brought into contact with a PnBA layer, and a subsequent debonding phase, where the probe is pulled away from the surface. The debonding process was separated into three distinct deformation mechanisms:  (1) the appearance of cavities throughout the adhesive layer; (2) lateral growth of these cavities within the plane of the adhesive layer; (3) the formation and eventual failure of a fibrillar structure as the adhesive is extended in the direction of the applied tensile load. Cavitation depends primarily on the elastic character of the adhesive, but the lateral cavity growth and extensional mechanisms are strongly affected by the ability of the adhesive to flow during the time scale of the experiment. The nature of these processes was determined by an effective Deborah number, defined as the terminal relaxation time of the polymer multiplied by the initial strain rate imposed during the debonding process.

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The uncertainty of the shape of the tip is a significant source of error in atomic force microscopy (AFM) based quantitative nanomechanical measurements. Using transmission electron microscopy, scanning electron microscopy, or tip reconstruction images, it is possible to parametrize the models of real AFM tips, which can be used in quantitative nanomechanical measurements. These measurements use algorithms described in this article that extend classical elastic, plastic, and adhesive models of contact mechanics. Algorithms are applicable to the tips of arbitrary axisymmetric shapes. Several models of AFM tip have been utilized. The goal of tip model parameterization is to develop AFM tip-independent quantitative mechanical measurements at the nanometer scale. Experimental results demonstrate independence of the AFM measurements from tips and their closeness to bulk measurements where available. In this article the authors show the correspondence between microtensile, nanoindentation, and AFM based indentation for measuring the modulus of a spin on low-k dielectric polymer thin film. These results provide a confidence that with the described procedures AFM can be used for reliable quantitative nanomechanical measurements.