XLII. The use of plasticine models to simulate the plastic flow of metals.

Abstract

The behaviour of plasticine when permanently deformed, is compared with that of an ideal metal, and the necessary conditions for similarity between their flow patterns are examined for flow in two and three dimensions. A brief account of the mechanical properties of plasticine includes a description of stress-strain curves obtained by compressing cylinders between lubricated plates at constant rates of loading. Plane strain experiments, using a plasticine model marked with a grid on a cross-section parallel to the plane of flow, are described, and photographs of the deformed grids are compared with theory. The processes thus examined were : extrusion through square and wedge-shaped dies; indentation of a plane surface by a single wedge and by a row of wedges; and compression of a narrow wedge by a flat die. The profile of a deep narrow block after a small indentation by a flat punch is also compared with theory. All these plane strain plasticine experiments agree well with theory. One experiment using a metal was performed—the compression of a narrow copper wedge by a smooth flat die. This copper wedge deformed in a similar way to the plasticine wedge.