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A finite two-dimensional (2D) foam sample bounded by walls contains inner bubbles (I-bubbles) and peripheric or edge bubbles (E-bubbles). We derive equations for the rate of area change of both types of bubbles, which depend linearly on the number of neighbours of a bubble but are, in general, not scale independent. From these equations we obtain global kinetic laws for the two aggregates (I- and E-) of bubbles. The topological operations that occur during coarsening of E-bubbles are identified and the effect of curvature of the wall on coarsening is discussed. Experimental results obtained with 2D (monolayer) foams are presented which, combined with theory, give a reasonable picture of the effect of boundaries on foam coarsening. A disturbance due to the bounding walls was not experimentally detected: I- and E-bubbles were found to grow in pace, their average areas remaining equal, with a global parabolic growth law. However, this property could not be inferred from the growth equations for individual I- and E-bubbles. [ABSTRACT FROM AUTHOR]

Experimental observations of the deformation of a monodisperse twodimensional (2D) monolayer foam in tension/compression are reported. The foam samples are bound by two parallel walls at a variable separation, w. At critical values of w, dislocations (5/7 pairs) nucleate at the periphery of the foam which then glide along directions at 60o to the walls. The dislocations may suffer reflection at the walls, with a change in Burgers vector. As a result of the glide process, the number of close-packed rows of cells parallel to the walls changes by one and a neck develops. Rearrangements of the bubbles to more stable configurations are also observed, following dislocation glide. A detailed analysis of the topology of nucleation, glide and reflection of dislocations is undertaken. The stress-strain relation is derived and used to calculate the yield stress of the honeycomb foam from the experimentally measured strains at which topological transitions occur. The yield stress is considerably lowered by the nucleation of dislocations and is affected by the liquid fraction in the foam. [ABSTRACT FROM AUTHOR]