Surface formulation for molecular interactions of macroscopic bodies

The determination of forces resulting from molecular interactions between macroscopic bodies is important for the analysis of a variety of processes such as sintering, adhesion, and fracture. Body forces resulting from these interactions are usually concentrated near the surfaces of the bodies and are responsible for phenomena such as surface tension and surface energy. In the formulation presented here, the volume integrated intermolecular force between bodies is partitioned to obtain a distribution of effective surface tractions. This new surface formulation eliminates the geometrical restrictions associated with the commonly used Derjaguin approximation. The influence of each body on the surface of any other body is represented by a new quantity: the inter-surface stress tensor. Additional forces resulting from interactions within the body, the surface tension, have been considered for liquid-like materials. These self interactions are modeled by the classical Young-Laplace equation relating the effective traction on a surface to the energy of the surface and its curvature. The surface formulation offers considerable reduction in computational complexity compared to a formulation. based on body forces. The efficacy of the technique is demonstrated using several examples. (C) 1997 Elsevier Science Ltd.