synopsisThe strength of adhesion has been determined experimentally for an elastomer layer coupled to a rigid substrate by interfacial chemical bonds of varying surface density. Sites for interfacial bonding were obtained by treating glass plates with mixtures of vinyland ethylsilanes in varying proportions. A layer of polybutadiene was then applied and cross-linked in situ by a free-radical process. Formation of interfacial bonds to vinyl groups (when present) on the glass substrate is inferred from the proportional increase in strength of adhesion under near-equilibrium conditions, i.e., at low rates of detachment and at high temperatures. A 35fold increase in strength was found for vinylsilane, relative to ethylsilane, in rough agreement with the relative magnitudes of the strengths of covalent and dispersion bonds. However, the absolute magnitudes were much greater than predicted, by a factor of about 25 in both cases. This is attributed to the polymeric character of the elastomer: many molecular bonds must be stressed in order to detach or rupture one.4 In agreement with this hypothesis, the strength of adhesion decreased with increasing crosslinking. Anomalously high adhesion was found with clean glass.It presumably reflects a specific bonding mechanism of unknown type.

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A new method for analyzing 3-D magnetic fields and currents in electrical machines excited from voltage sources using the A -# method has been developed.The basic idea and the finite element formulation of the method are described. The effectiveness of the method is shown by some examples of application.

Mesh quality strongly affects the solution accuracy in electromagnetic finite-element analysis. Hence, the realization of adequate mesh generation becomes a very important task. Several adaptive meshing methods for automatic adjustments of the mesh density in accordance with the shape and complexity of the analyzed problem have been proposed. However, the most of them are not enough robust, some are quite laborious and could not be universally used for adaptive meshing of complex analysis models. In this paper, a new adaptive mesh refinement method based on magnetic field conservation at the border between finite elements is proposed. The proposed error estimation method provides easy mesh refinements, and generates smaller element within regions with large curvature of the magnetic flux lines. The proposed adaptive mesh refinement method based on non-conforming edge finite elements, which could avoid generation of flat or ill-shaped elements, was applied to a simple magnetostatic permanent magnet model. To confirm the validity and accuracy, the obtained results were compared with those obtained by means of the Zienkiewicz-Zhu (ZZ) error estimator. The results show that the computational error using the proposed method was reduced down to 1% compared with that of the ZZ method, which yields error of 8.6%, for the same model