Papers by Author: Wilhelm Eib

Abstract: The transition from elastic behaviour to plastic ow of technical materials under the inuence of increasing mechanical load is obviously of major technical importance. Nevertheless it is a challenge to formalize this transition in terms of consistent eld theories. We adopt here the beautiful theoretical work of Kröner [1], Bilby [2], and Kunin [3], who have shown how this formalization can be done. We shall go beyond their results by assuming energy dissipation if dislocations are moved through surfaces as suggested earlier [4] due to the energy density contribution from inner curved surfaces. Sometimes the mutual movement of adhering planes is described in terms of a stick-slip movement, meaning that the solid switches between elastic and plastic, possibly (and in fact in most experimental cases) showing a hysteresis between the two. Earthquake shear waves, e.g., are a dramatic example. Classical eld theories can hardly account for this eect. We shall try to describe the solid deformations as dislocations in two dierent phases, allowing for transitions between these phases. The tool is the Ginzburg-Landau-formalism in the form Haken [5] used for selforganizing quantized systems. We are aware of the fact that this procedure is consequent only after the above mentioned classical eld theories have been quantized, a still open task for theoretical physicists, but we feel that the practical benet is worth the cavalier assumptions.

Abstract: The liquid phase of adhesives is most readily described by the theory of solutions. Adhesives act on phase boundaries. Yet right there, the fact that an adhesive is a solution does not fully describe its special performance. Some of the outstanding properties of adhesives are designed by the use non- soluble components, like Nanofillers, fibre reinforcements, color pigments, additives for the improvement of electrical and heat conductivity, etc. We would like to compare near phase boundary properties inside adhesives and outside near the substrates. We expect a relation between rheology and thermodynamical parameters of adhesion. Solutions are characterized by their chemical potential. We expect the above relationship to manifest itself by a change of the chemical potential near a phase boundary.